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THE ENGINEERED WOOD ASSOCIATION Be Constructive WOOD Wood Is the Right Choice for a Host of Construction Applications

THE ENGINEERED WOOD ASSOCIATION Be Constructive WOOD Wood Is the Right Choice for a Host of Construction Applications

ENGINEERED CONSTRUCTION GUIDE

APA THE ASSOCIATION Be Constructive WOOD Wood is the right choice for a host of construction applications. It is the earth’s natural, energy efficient and renewable building material. Engineered wood is a better use of wood. It uses less wood to make more wood products. That’s why using APA trademarked I-, glued laminated timbers, laminated veneer , and is constructive ... for the environment, for innovative design, and for strong, durable buildings.

A few facts about wood. We’re not running out of trees. One-third of the United States land base – 731 million acres – is covered by forests. About two-thirds of that 731 million acres is suitable for repeated planting and harvesting of timber. But only about half of the land suitable for growing timber is open to logging. Most of that harvestable acreage also is open to other uses, such as camping, hiking, and hunting. Forests fully cover one-half of Canada’s land mass. Of this forestland, nearly half is considered productive, or capable of producing timber on a sustained yield basis. Canada has the highest per capita accumulation of protected natural areas in the world – areas including national and provincial parks.

We’re growing more wood every day. American landowners plant more than two billion trees every year. In addition, millions of trees seed naturally. The forest products industry, which comprises about 15 percent of forestland ownership, is responsible for 41 percent of replanted forest acreage. That works out to more than one billion trees a year, or about three million trees planted every day. This high rate of replanting accounts for the fact that each year, 27 percent more timber is grown than is harvested. Canada’s replanting record shows a fourfold increase in the number of trees planted between 1975 and 1990.

Manufacturing wood is energy efficient. Percent of Percent of Wood products made up 47 percent of all Material Production Energy Use industrial raw materials manufactured in the Wood 47 4 United States, yet consumed only 4 percent of the energy needed to manufacture all Steel 23 48 industrial raw materials, according to Aluminum 2 8 a 1987 study.

Constructive news for a healthy planet. For every ton of wood grown, a young forest produces 1.07 tons of oxygen and absorbs 1.47 tons of carbon dioxide.

• ALL RIGHTS RESERVED. • ANY COPYING, MODIFICATION, DISTRIBUTION OR OTHER USE OF THIS PUBLICATION OTHER THAN AS EXPRESSLY AUTHORIZED BY APA IS PROHIBITED BY THE U.S. COPYRIGHT LAWS. THE U.S. IS PROHIBITED BY APA BY AUTHORIZED THAN AS EXPRESSLY OTHER USE OF THIS PUBLICATION DISTRIBUTION OR OTHER MODIFICATION, • ANY COPYING, • ALL RIGHTS RESERVED. Wood. It’s the constructive choice for NOTICE: the environment. The recommendations in A this guide apply only to AP panels that bear the APA THE ENGINEERED trademark. Only panels WOOD ASSOCIATION bearing the APA trademark RATED SHEATHING15/32 INCH are subject to the 32/16 Association’s quality SIZED FOR SPACING EXPOSURE 1 auditing program. 000 PS 1-95 C-D PRP-108 APA – THE ENGINEERED WOOD ASSOCIATION APA ©2001 PA engineered wood products are used in a wide range A of construction applications. Time-tested panel products are used in traditional wood-frame construction and in combination with other engineered wood products and systems. For low in-place cost, versatility, and superior performance, APA engineered wood systems are simply hard to beat.

This guide from APA – The Engineered Wood Association is designed as a reference manual for engineered wood specifiers and users in both residential and commercial construction. It contains up-to-date information on APA Performance Rated Panels, glulam, I-joists, specification practices, , wall and roof systems, diaphragms and shear walls, fire-rated systems and methods of finishing.

If what you want to know about engineered wood construction systems isn’t fully explained here, chances are it is in one of our many other publications. Simply write for the appropriate title or titles cited throughout this publication. Product and application information can also be found on the APA web site, at www.apawood.org. Or, for individual assistance with specific design questions or problems, contact the APA Product Support Help Desk or the nearest APA regional field office listed on the back cover. GUIDE TO ENGINEERED WOOD PRODUCTS CONTENTS

GUIDE TO ENGINEERED WALL CONSTRUCTION ...... 38 WOOD PRODUCTS ...... 4 APA Sturd-I-Wall ...... 38 Product Selection, Specification, Product Selection, Specification, APA Panel and Lap Over and Handling and Handling ...... 4 Nailable Sheathing ...... 40 APA Panel Wall Sheathing ...... 42 The evolution of engineered wood PANEL SELECTION AND The Code Plus Wall ...... 43 products over the past few decades SPECIFICATION ...... 5 APA Sheathing Under ...... 44 Manufacturing and Siding Joint Details ...... 44 has greatly expanded building options Performance Standards ...... 5 APA Rated Siding Patterns Grade Designations ...... 5 and Grades ...... 46 and methods in all forms of residential Sanded, Unsanded and Finishing Plywood for and commercial construction. The Touch-Sanded Panels ...... 5 Exterior Exposure ...... 46 Bond Classificiation ...... 6 Interior Paneling ...... 49 next 21 pages of this APA Design/ Group Number ...... 6 Panel Backing ...... 49 Span Ratings ...... 11 APA Panel Shear Walls ...... 50 Construction guide provide product How To Order APA Panels ...... 11 information and specification recom- Grade Availability ...... 12 ROOF CONSTRUCTION ...... 52 Metric Conversions ...... 12 APA Panel Roof Sheathing ...... 52 mendations for several of the most Panel Specification Guide ...... 12 The Code Plus Roof ...... 52 Panel Storage and Handling ...... 17 Preframed Roof Panels ...... 54 common engineered wood products – Long Span Systems ...... 56 plywood, oriented strand board, GLULAM SELECTION AND Plywood Under Special Coatings ...... 56 SPECIFICATION ...... 18 APA Panel Soffits ...... 57 composite panels, glulam, and I-joists. Balanced and Unbalanced Beams . . . . .18 APA Panel Roof Diaphragms ...... 59 Other engineered wood products that Allowable Design Properties ...... 18 Sizes ...... 18 BUILDING REQUIREMENTS AND are often used in the construction Appearance Classification ...... 18 RELATED PANEL SYSTEMS . . . . .61 Section Properties and Capacities . . . . .19 Fire-resistant Construction ...... 61 systems described in this guide include Camber ...... 19 Wind-resistive Roofs ...... 64 rim board and laminated veneer Trademarks and Acceptances ...... 20 Noise Transmission Control ...... 65 Specification Guide for Energy Conservation ...... 67 lumber (LVL). Structural Glued Laminated Condensation: Its Cause and Control . .68 Timber (Glulam) ...... 20 Thermal Resistance of “Engineered wood” describes wood Glulam Storage Wood Structural Panels ...... 69 and Handling ...... 21 products that are engineered for struc- RELATED PANEL SYSTEMS ...... 69 tural applications. Having been used I-JOISTS SELECTION AND The Permanent Wood Foundation . . . . .69 SPECIFICATION ...... 22 Plywood for Outdoor Decks ...... 69 since the 1940s, plywood is considered APA PRI-400 ...... 22 Plywood for Concrete Forming ...... 69 Residential Floor Spans ...... 22 Structural Insulated Panels ...... 70 by many to be the original engineered Specifying APA Performance APA Panels Over Metal ...... 70 wood product. All glued engineered Rated I-Joists ...... 23 APA Panel Systems I- Storage and Handling ...... 25 Over Concrete Slabs ...... 71 wood products are made by combin- Special Floor Surfacing ...... 71 FLOOR CONSTRUCTION ...... 26 ing wood strands, veneers, lumber or APA Rated Sturd-I-Floor ...... 26 ADDITIONAL INFORMATION . . . .71 other wood fiber with glue to form a The Code Plus Floor ...... 29 About APA – The Engineered Wood Sturd-I-Floor 32 oc and 48 oc ...... 29 Association and Engineered large composite structural unit. They APA Performance Rated Rim Board . . . .29 Wood Systems ...... 71 are designed and manufactured to The APA Glued Floor System ...... 30 APA Panel Subflooring ...... 32 maximize the natural strength and Lightweight Concrete Over APA Panels ...... 33 stiffness characteristics of wood by APA Plywood Underlayment ...... 33 orienting the wood veneers, strands or Over APA Panel Subfloors ...... 34 laminations and by combining wood Ceramic Tile Over APA Plywood ...... 35 with durable adhesives. APA Panel Stair Treads and Risers . . . . .36 Heavy Duty Plywood Floors ...... 36 PANEL SELECTION AND SPECIFICATION

Manufacturing and veneer species and thickness, etc., are in Performance Standards many instances identical to panel grades TABLE 1 Panels for construction and industrial as defined in Product Standard PS 1-95. VENEER GRADES applications can be manufactured Smooth, paintable. Not more than Typical APA Performance Rated Panel 18 neatly made repairs, boat, in a variety of ways – as plywood sled, or type, and parallel to trademarks are illustrated and explained A (cross-laminated ), as grain, permitted. Wood or syn- on page 6. thetic repairs permitted. May be composite panels (veneer faces bonded used for natural finish in less demanding applications. to wood strand cores), or as oriented Grade Designations Solid surface. Shims, sled or router strand board (OSB). repairs, and tight knots to 1 inch Structural panel grades are generally B across grain permitted. Wood or synthetic repairs permitted. Some Some plywood panels are manufactured identified in terms of the veneer grade minor splits permitted. under the detailed manufacturing speci- used on the face and back of the panel Improved C veneer with splits lim- (e.g., A-B, B-C, etc.), or by a name sug- ited to 1/8-inch width and knot- fications or under the performance test- C holes or other open defects limited gesting the panel’s intended end use Plugged to 1/4 x 1/2 inch. Wood or syn- ing provisions of Voluntary Product thetic repairs permitted. Admits Standard PS 1-95 for Construction and (e.g., APA RATED SHEATHING, APA some broken grain. Tight knots to 1-1/2 inch. Industrial Plywood, developed coopera- RATED STURD-I-FLOOR, etc.). See Knotholes to 1 inch across grain Tables 2-4. C and some to 1-1/2 inch if total tively by the plywood industry and the width of knots and knotholes is U.S. Department of Commerce. Other within specified limits. Synthetic or Veneer grades define veneer appearance wood repairs. Discoloration and plywood panels, however, as well as in terms of natural unrepaired growth sanding defects that do not impair strength permitted. Limited splits composite and OSB panels, are characteristics and allowable number allowed. Stitching permitted. manufactured under the provisions of and size of repairs that may be made Knots and knotholes to 2-1/2-inch width across grain and 1/2 inch APA PRP-108, Performance Standards during manufacture. See Table 1. D larger within specified limits. Limited splits are permitted. and Policies for Structural-Use Panels, The highest quality commonly available Stitching permitted. Limited to or under Voluntary Product Standard veneer grade is A. The minimum grade Exposure 1 or Interior panels. PS 2-92, Performance Standard for of veneer permitted in Exterior plywood Wood-Based Structural-Use Panels, is C-grade. D-grade veneer is used in that establish performance criteria for panels intended for interior use or Unsanded and touch-sanded panels, specific designated construction applications protected from long-term and panels with B-grade or better veneer applications. exposure to weather. on one side only, usually carry the APA These APA Performance Rated Panels trademark on the panel back. Panels Sanded, Unsanded and with both sides of B-grade or better are easy to use and specify because the Touch-Sanded Panels veneer, or with special overlaid surfaces recommended end use and maximum Panels with B-grade or better veneer (such as HIGH DENSITY OVERLAY) support spacings are clearly indicated faces are always sanded smooth in usually carry the APA trademark on the in the APA trademark. By broadening manufacture to fulfill the requirements panel edge. the range of panel configuration and of their intended end use – applications composition, APA Performance Rated such as cabinets, shelving, furniture, (a) The National Evaluation Service is sponsored Panels allow more efficient use of raw built-ins, etc. APA RATED SHEATHING jointly by two model code organizations – the Building Officials and Code Administrators materials. APA PRP-108 Performance panels are unsanded since a smooth International, promulgators of the National Standards are recognized by the National Building Code and the Southern Building Code surface is not a requirement of their Congress International, promulgators of the Evaluation Service, the International intended end use. Still other panels – Standard Building Code. A third model code Conference of Building Officials (ICBO) organization is the International Conference of APA UNDERLAYMENT, APA RATED Building Officials, promulgators of the Uniform and HUD.(a) PRP-108, PS-1 and/or the Building Code. See National Evaluation Service STURD-I-FLOOR, APA C-D PLUGGED, Report No. NER-108 or ICBO ER-5681 for allow- PS-2 grade conformance where applica- and APA C-C PLUGGED – require only able values and/or conditions of use concerning ble are given in the lower portion of the panel material presented in this brochure. It is touch sanding for “sizing” to make the subject to reexamination, revisions, and possible APA trademark. Plywood panels, panel thickness more uniform. cancellation. depending on glueline classification, HUD recognition of wood-based APA Performance Rated Panels is contained in Use of Materials Bulletin UM-40.

5 PANEL SELECTION AND SPECIFICATION

Bond Classification APA trademarked panels may be APA APA APA produced in four bond classifications – THE ENGINEERED THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION WOOD ASSOCIATION Exterior, Exposure 1, Exposure 2, and 1 RATED STURD-I-FLOOR 1 RATED SHEATHING 1 RATED SIDING Interior. The bond classification relates 2 23/32 INCH 6 23/32 INCH 6 303-18-S/W 9 24 oc 2 48/24 11/32 INCH SIZED FOR SPACING 6 2 GROUP 1 3 T&G NET WIDTH 47-1/2 SIZED FOR SPACING 16 oc 10 to glue bond, and thus to structural 4 EXPOSURE 1 4 EXPOSURE 1 SIZED FOR SPACING 7 000 7 4 EXTERIOR 000 000 7 integrity of the panel. Since aesthetic 5 PS 1-95 UNDERLAYMENT 5 PS 2-92 SHEATHING PRP-108 PRP-108 HUD-UM-40 11 5 PS 1-95 PRP-108 8 8 8 FHA-UM-40 11 (nonstructural) attributes of panels may CONSTRUCTION SHEATHING 12 be compromised to some degree by 13 2R48/2F24 17.5mm exposure to weather(b), installation 14 CSA 0325

STRENGTH AXIS recommendations in this publication are 15 THIS DIRECTION designed to provide optimum overall performance. 1 Panel grade 7 Mill number 13Panel mark – Rating and 2 Span Rating 8 APA’s performance rated end-use designation, NOTE: Bond classification relates to moisture 3 Tongue-and- panel standard Canadian standard resistance of the glue bond and does not relate to 4 Bond classification 9 Siding face grade 14Canadian performance rated panel standard fungal decay resistance of the panel. Fungal decay 5 Product Standard 10Species group number of wood products may occur when the moisture 11HUD/FHA recognition 15Panel face orientation 6 Thickness indicator content exceeds 20% for an extended period. See 12Panel grade, Canadian APA Techinical Note R495, Controlling Decay in standard Wood Construction, for a discussion of fungal decay. Prevention of fungal decay is a function of proper design, material specification, construction and maintenance of the structure. While this publica- Exposure 2 panels (identified as Interior thick or less and Decorative panels of tion includes many of the applicable provisions, reference to local building codes and other design type with intermediate glue under PS 1) any thickness. These are identified by documents is also necessary. are intended for protected construction face species because they are chosen Exterior panels have a fully waterproof applications where potential for condi- primarily for appearance and used in bond and are designed for applications tions of high humidity exist. applications where structural integrity is subject to long-term exposure to the Interior panels which lack further glue- not critical. Sanded panels greater than weather or to moisture. line information in their trademarks are 3/8 inch are identified by face species if C or D grade backs are at least 1/8 inch Exposure 1 panels have a fully water- manufactured with interior glue and are and are no more than one species group proof bond and are designed for appli- intended for interior applications only. number larger. Some species are used cations where construction delays may Group Number widely in plywood manufacture; others be expected prior to providing protec- Plywood can be manufactured from rarely. Check local availability if a partic- tion. Exposure 1 panels are made with over 70 species of wood. These species ular species is desired. the same exterior adhesives used in are divided on the basis of strength Exterior panels. However, because other and stiffness into five Groups under (b) Panel surfaces may become uneven and compositional factors may affect bond irregular under prolonged moisture exposure. Voluntary Product Standard PS 1. Panels should be allowed to dry, and panel joints performance, only Exterior panels and surfaces may need to be sanded before Strongest species are in Group 1; the applying some finish materials. should be used for long-term exposure next strongest in Group 2, and so on. to the weather.(c) (c) Exposure 1 panels may also be used when The Group number that appears in the exposure to the outdoors is on the underside only, trademark on some APA trademarked such as at roof overhangs. Appearance characteris- NOTE: Plywood APA Rated Sheathing tics of the panel grade should be considered. Exposure 1, sometimes called “CDX” in the trade, panels – primarily sanded grades – is is occasionally mistaken as an Exterior panel and erroneously used in applications for which it does based on the species used for face and not possess the required resistance to weather. back veneers. Where face and back “CDX” should only be used for applications as outlined under Exposure 1 above. For sheathing veneers are not from the same species grade panels that will be exposed long term to the Group, the higher Group number is weather, specify APA Rated Sheathing Exterior (C-C Exterior plywood under PS 1). used, except for sanded panels 3/8 inch

6 TABLE 2 GUIDE TO APA PERFORMANCE RATED PANELS(a)(b) FOR APPLICATION RECOMMENDATIONS, SEE FOLLOWING PAGES. APA RATED SHEATHING Specially designed for subflooring and wall and roof sheathing. Typical TrademarkAPA APA Also good for a broad range of other construction and industrial THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION applications. Can be manufactured as OSB, plywood, or a composite panel. BOND CLASSIFICATIONS: Exterior, Exposure 1, Exposure 2. RATED SHEATHING RATED SHEATHING 40/20 19/32 INCH 24/16 7/16 INCH COMMON THICKNESSES: 5/16, 3/8, 7/16, 15/32, 1/2, 19/32, SIZED FOR SPACING SIZED FOR SPACING 5/8, 23/32, 3/4. EXPOSURE 1 EXPOSURE 1 000 000 PS 2-92 SHEATHING PRP-108 HUD-UM-40 PRP-108 HUD-UM-40

APA STRUCTURAL I Unsanded grade for use where shear and cross-panel strength RATED SHEATHING(c) APA APA properties are of maximum importance, such as panelized roofs Typical TrademarkTHE ENGINEERED THE ENGINEERED and diaphragms. Can be manufactured as OSB, plywood, or a com- WOOD ASSOCIATION WOOD ASSOCIATION posite panel. BOND CLASSIFICATIONS: Exterior, Exposure 1. RATED SHEATHING RATED SHEATHING STRUCTURAL I 32/16 15/32 INCH COMMON THICKNESSES: 5/16, 3/8, 7/16, 15/32, 1/2, 19/32, 15/32 INCH 32/16 SIZED FOR SPACING 5/8, 23/32, 3/4. SIZED FOR SPACING EXPOSURE 1 EXPOSURE 1 000 000 STRUCTURAL I RATED PS 1-95 C-D PRP-108 DIAPHRAGMS-SHEAR WALLS PANELIZED ROOFS PRP-108 HUD-UM-40

APA RATED STURD-I-FLOOR Specially designed as combination subfloor-underlayment. Provides Typical TrademarkAPA APA smooth surface for application of carpet and pad and possesses high THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION concentrated and impact load resistance. Can be manufactured as OSB, plywood, or a composite panel. Available edge or RATED STURD-I-FLOOR RATED STURD-I-FLOOR 24 oc 23/32 INCH 20 oc 19/32 INCH tongue and-groove. BOND CLASSIFICATIONS: Exterior, Exposure 1, SIZED FOR SPACING SIZED FOR SPACING T&G NET WIDTH 47-1/2 T&G NET WIDTH 47-1/2 Exposure 2. COMMON THICKNESSES: 19/32, 5/8, 23/32, EXPOSURE 1 EXPOSURE 1 000 000 3/4, 1, 1-1/8. PS 2-92 SINGLE FLOOR PRP-108 HUD-UM-40 PRP-108 HUD-UM-40

APA RATED SIDING For exterior siding, fencing, etc. Can be manufactured as plywood, Typical TrademarkAPA APA as a composite panel or as an overlaid OSB. Both panel and lap siding THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION available. Special surface treatment such as V-groove, channel groove, deep groove (such as APA Texture 1-11), brushed, rough sawn and RATED SIDING RATED SIDING 19/32 INCH 303-18-S/W overlaid (MDO) with smooth- or texture-embossed face. Span Rating 24 oc 11/32 INCH SIZED FOR SPACING 16 oc GROUP 1 (stud spacing for siding qualified for APA Sturd-I-Wall applications) EXTERIOR SIZED FOR SPACING EXTERIOR 000 and face grade classification (for veneer-faced siding) indicated in PRP-108 HUD-UM-40 000 PS 1-95 PRP-108 trademark. BOND CLASSIFICATION: Exterior. COMMON FHA-UM-40 THICKNESSES: 11/32, 3/8, 7/16, 15/32, 1/2, 19/32, 5/8.

(a) Specific grades, thicknesses and bond classifications may be in limited (c) All plies in Structural I plywood panels are special improved grades and supply in some areas. Check with your supplier before specifying. panels marked PS 1 are limited to Group 1 species. Other panels marked (b) Specify Performance Rated Panels by thickness and Span Rating. Structural I Rated qualify through special performance testing. Span Ratings are based on panel strength and stiffness. Since these properties are a function of panel composition and configuration as well as thickness, the same Span Rating may appear on panels of different thickness. Conversely, panels of the same thickness may be marked with different Span Ratings.

7 PANEL SELECTION AND SPECIFICATION

TABLE 3 GUIDE TO APA SANDED & TOUCH-SANDED PLYWOOD PANELS(a)(b)(c) FOR APPLICATION RECOMMENDATIONS, SEE FOLLOWING PAGES. APA A-A Use where appearance of both sides is important for interior Typical Trademark (mark on panel edge) applications such as built-ins, cabinets, furniture, partitions; and exterior applications such as fences, signs, boats, shipping containers, tanks, ducts, etc. Smooth surfaces suitable for painting. BOND CLASSIFICATIONS: Interior, Exposure 1, Exterior. COMMON THICKNESSES: 1/4, 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4. A-A ¥ G-1 ¥ EXPOSURE 1-APA ¥ 000 ¥ PS1-95

APA A-B For use where appearance of one side is less important but where Typical Trademark (mark on panel edge) two solid surfaces are necessary. BOND CLASSIFICATIONS: Interior, Exposure 1, Exterior. COMMON THICKNESSES: 1/4, 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4. A-B ¥ G-1 ¥ EXPOSURE 1-APA ¥ 000 ¥ PS1-95

APA A-C For use where appearance of only one side is important in exterior Typical TrademarkAPA or interior applications, such as soffits, fences, farm buildings, etc.(f) THE ENGINEERED BOND CLASSIFICATION: Exterior. COMMON THICKNESSES: 1/4, WOOD ASSOCIATION 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4.

A-C GROUP 1

EXTERIOR 000 PS 1-95

APA A-D For use where appearance of only one side is important in interior Typical TrademarkAPA applications, such as paneling, built-ins, shelving, partitions, flow racks, THE ENGINEERED (f) WOOD ASSOCIATION etc. BOND CLASSIFICATIONS: Interior, Exposure 1. COMMON THICKNESSES: 1/4, 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4. A-D GROUP 1

EXPOSURE 1 000 PS 1-95

APA B-B Utility panels with two solid sides. BOND CLASSIFICATIONS: Interior, Typical Trademark (mark on panel edge) Exposure 1, Exterior. COMMON THICKNESSES: 1/4, 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4. B-B ¥ G-2 ¥ EXT-APA ¥ 000 ¥ PS1-95

APA B-C Utility panel for farm service and work buildings, boxcar and truck Typical TrademarkAPA linings, containers, tanks, agricultural equipment, as a base for THE ENGINEERED exterior coatings and other exterior uses or applications subject to high WOOD ASSOCIATION or continuous moisture.(f) BOND CLASSIFICATION: Exterior. COMMON

B-C GROUP 1 THICKNESSES: 1/4, 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4.

EXTERIOR 000 PS 1-95

APA B-D Utility panel for backing, sides of built-ins, industry shelving, slip Typical TrademarkAPA sheets, separator boards, bins and other interior or protected THE ENGINEERED (f) WOOD ASSOCIATION applications. BOND CLASSIFICATIONS: Interior, Exposure 1. COMMON THICKNESSES: 1/4, 11/32, 3/8, 15/32, 1/2, 19/32, B-D GROUP 2 5/8, 23/32, 3/4.

EXPOSURE 1 000 PS 1-95

Continued on next page

8 TABLE 3

CONTINUED

APA UNDERLAYMENT For application over structural subfloor. Provides smooth surface for Typical Trademark APA application of carpet and pad and possesses high concentrated and THE ENGINEERED WOOD ASSOCIATION impact load resistance. For areas to be covered with resilient flooring, specify panels with “sanded face.”(e) BOND CLASSIFICATIONS: Interior, UNDERLAYMENT (d) GROUP 1 Exposure 1. COMMON THICKNESSES : 1/4, 11/32, 3/8, 15/32, 1/2, EXPOSURE 1 19/32, 5/8, 23/32, 3/4. 000 PS 1-95

APA C-C PLUGGED(g) For use as an underlayment over structural subfloor, refrigerated or Typical TrademarkAPA controlled atmosphere storage rooms, pallet fruit bins, tanks, boxcar THE ENGINEERED and truck floors and linings, open soffits, and other similar applications WOOD ASSOCIATION where continuous or severe moisture may be present. Provides smooth C-C PLUGGED surface for application of carpet and pad and possesses high concen- GROUP 2 EXTERIOR trated and impact load resistance. For areas to be covered with resilient 000 flooring, specify panels with “sanded face.”(e) BOND CLASSIFICATION: PS 1-95 Exterior. COMMON THICKNESSES(d) : 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4.

APA C-D PLUGGED For open soffits, built-ins, cable reels, separator boards and other Typical TrademarkAPA interior or protected applications. Not a substitute for Underlayment or THE ENGINEERED APA Rated Sturd-I-Floor as it lacks their puncture resistance. BOND WOOD ASSOCIATION CLASSIFICATIONS: Interior, Exposure 1. COMMON THICKNESSES: C-D PLUGGED 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4. GROUP 2 EXPOSURE 1 000 PS 1-95

(a) Specific plywood grades, thicknesses and bond classifications may be in (d) Some panels 1/2 inch and thicker are Span Rated and do not contain limited supply in some areas. Check with your supplier before specifying. species group number in trademark. (b) Sanded Exterior plywood panels, C-C Plugged, C-D Plugged and (e) Also available in Underlayment A-C or Underlayment B-C grades, marked Underlayment grades can also be manufactured in Structural I either “touch sanded” or “sanded face.” (all plies limited to Group 1 species). (f) For nonstructural floor underlayment, or other applications requiring (c) Some manufacturers also produce plywood panels with premium N-grade improved inner ply construction, specify panels marked either “plugged veneer on one or both faces. Available only by special order. Check with inner plies” (may also be designated plugged crossbands under face or the manufacturer. plugged crossbands or core); or “meets underlayment requirements.” (g) Also may be designated APA Underlayment C-C Plugged.

9 PANEL SELECTION AND SPECIFICATION

TABLE 4 GUIDE TO APA SPECIALTY PLYWOOD PANELS(a) FOR APPLICATION RECOMMENDATIONS, SEE FOLLOWING PAGES. APA DECORATIVE Rough-sawn, brushed, grooved, or striated faces. For paneling, interior Typical Trademark APA accent walls, built-ins, counter facing, exhibit displays. Can also be THE ENGINEERED WOOD ASSOCIATION made by some manufacturers in Exterior for exterior siding, gable ends, fences and other exterior applications. Use recommendations for DECORATIVE Exterior panels vary with the particular product. Check with the GROUP 2 EXPOSURE 1 manufacturer. BOND CLASSIFICATIONS: Interior, Exposure 1, Exterior. 000 COMMON THICKNESSES: 5/16, 3/8, 1/2, 5/8. PS 1-95

APA HIGH DENSITY OVERLAY (HDO)(b) Has a hard semi-opaque resin-fiber overlay on both faces. Abrasion Typical Trademark (mark on panel edge) resistant. For concrete forms, cabinets, countertops, signs, tanks. Also available with skid-resistant screen-grid surface. BOND CLASSIFICA- HDO ¥ A-A ¥ G-1 ¥ EXT-APA ¥ 000 ¥ PS 1-95 TION: Exterior. COMMON THICKNESSES: 3/8, 1/2, 5/8, 3/4.

APA MEDIUM DENSITY OVERLAY (MDO)(b) Smooth, opaque, resin-fiber overlay on one or both faces. Ideal base Typical TrademarkAPA for , both indoors and outdoors. For exterior siding, paneling, THE ENGINEERED WOOD ASSOCIATION shelving, exhibit displays, cabinets, signs. BOND CLASSIFICATION: Exterior. COMMON THICKNESSES: 11/32, 3/8, 15/32, 1/2, 19/32, M. D. OVERLAY 5/8, 23/32, 3/4. GROUP 1 EXTERIOR 000 PS 1-95

APA MARINE Ideal for boat hulls. Made only with Douglas- or western . Typical Trademark (mark on panel edge) Subject to special limitations on core gaps and face repairs. Also available with HDO or MDO faces. BOND CLASSIFICATION: Exterior. COMMON THICKNESSES: 1/4, 3/8, 1/2, 5/8, 3/4. MARINE ¥ A-A ¥ EXT-APA ¥ 000 ¥ PS 1-95

APA PLYFORM CLASS I(b) Concrete form grades with high reuse factor. Sanded both faces and Typical Trademark APA mill-oiled unless otherwise specified. Special restrictions on species. Also THE ENGINEERED WOOD ASSOCIATION available in HDO for very smooth concrete finish, and with special overlays. BOND CLASSIFICATION: Exterior. COMMON THICKNESSES: PLYFORM 19/32, 5/8, 23/32, 3/4. B-B CLASS 1 EXTERIOR 000 PS 1-95

APA PLYRON face on both sides. Faces tempered, untempered, smooth Typical Trademark (mark on panel edge) or screened. For countertops, shelving, cabinet doors, flooring. BOND CLASSIFICATIONS: Interior, Exposure 1, Exterior. COMMON PLYRON ¥ EXPOSURE 1 ¥ APA ¥ 000 THICKNESSES: 1/2, 5/8, 3/4.

(a) Specific plywood grades, thicknesses and bond classifications may be in (b) Can also be manufactured in Structural I (all plies limited to limited supply in some areas. Check with your supplier before specifying. Group 1 species).

10 Span Ratings underlayment) applications under How to Order APA Panels APA RATED SHEATHING, APA RATED carpet and pad and are manufactured Sanded and Touch-Sanded Panels: STURD-I-FLOOR and APA RATED with Span Ratings of 16, 20, 24, 32 and Designate thickness, APA trademark, SIDING carry numbers in their trade- 48 inches. The Span Ratings for APA grade, Group number(b), bond classifi- marks called Span Ratings. These RATED STURD-I- FLOOR panels, like cation, dimensions, number of pieces. denote the maximum recommended those for APA RATED SHEATHING, are For example: center-to-center spacing in inches of based on application of the panel with 3/4" APA A-A, Group 1, Exterior, supports over which the panels should the long dimension or strength axis 48" x 96", 100 pcs. be placed in construction applications. across three or more supports. 3/8" APA Underlayment, Group 1, Except for APA RATED SIDING panels, APA RATED SIDING is available with Exposure 1, 48" x 96", 100 pcs. the Span Rating applies when the long Span Ratings of 16 and 24 inches. (Designate “sanded face” if touch- panel dimension or strength axis is Span-rated panels and lap siding may be sanded grades are to be used under across supports, unless the strength axis used direct to studs or over nonstruc- resilient flooring, or see Table 11 for is otherwise identified. The Span Rating tural wall sheathing (Sturd-I-Wall con- additional grades.) of APA RATED SIDING panels applies struction), or over nailable panel or when installed vertically. lumber sheathing (double wall construc- (b) Underlayment and C-C Plugged panels The Span Rating on APA RATED tion). Panels and lap siding with a Span 1/2 inch and thicker are generally span rated and do not contain species group number in SHEATHING panels appears as two Rating of 16 inches may be applied trademark. Designate Span Rating. numbers separated by a slash, such as direct to studs spaced 16 inches on 32/16, 48/24, etc.(a) The left-hand center. Panels and lap siding bearing a Performance Rated Panels: Designate number denotes the maximum recom- Span Rating of 24 inches may be used thickness, APA trademark, grade, Span mended spacing of supports when the direct to studs 24 inches on center. All Rating, bond classification, dimensions, panel is used for roof sheathing with the RATED SIDING panels may be applied number of pieces. For example: long dimension or strength axis of the horizontally direct to studs 16 or panel across three or more supports. 24 inches on center provided horizontal 15/32" APA RATED SHEATHING, The right-hand number indicates the joints are blocked. When used over 32/16, Exposure 1, 48" x 96", 100 pcs. maximum recommended spacing of nailable structural sheathing, the Span supports when the panel is used for Rating of APA RATED SIDING panels 23/32" APA RATED STURD-I-FLOOR subflooring with the long dimension or refers to the maximum recommended 24 oc, Exterior, 48"(c) x 96", 100 pcs. strength axis of the panel across three spacing of vertical rows of nails rather (Note “square edge” or “tongue-and- or more supports. A panel marked than to stud spacing. groove” as desired.) 32/16, for example, may be used for For a description of Span Ratings under roof decking over supports up to (c) Most tongue-and-groove panels are manu- the Canadian Standard for Construction factured with a 47-1/2-inch net face width, 32 inches on center or for subflooring although manufacturing practices vary. Check Sheathing, refer to the APA Product with your supplier. over supports up to 16 inches on center. Guide: Oriented Strand Board, The Span Rating on APA RATED Form W410. STURD-I-FLOOR and APA RATED SIDING panels appears as a single num- (a) Exceptions are APA RATED SHEATHING intended for use as wall sheathing only, and APA ber. APA RATED STURD-I-FLOOR RATED WALL BRACING. The trademarks for such panels contain a single number similar to panels are designed specifically the Span Rating for APA RATED SIDING. for single-floor (combined subfloor-

11 PANEL SELECTION AND SPECIFICATION

Rated Sidings: Designate thickness, Metric Conversions PANEL SPECIFICATION APA trademark, face grade (for APA Metric equivalents of nominal thick- GUIDE(1) RATED SIDING-303), Span Rating, nesses and common sizes of wood struc- texture, pattern, dimensions, number tural panels are tabulated below (1 inch CSI* Division 3 – of pieces. For example: = 25.4 millimeters): Concrete 19/32" APA RATED SIDING A. Materials 303-18-W, 16 oc, rough-sawn Texture 1. Forms – Plywood concrete forms 1-11®, grooves 4" o.c., 48" x 96", PANEL NOMINAL DIMENSIONS shall be (specify appropriate grade):(2) (WIDTH X LENGTH) 100 pcs. (Note manufacturer’s trade m APA PLYFORM CLASS I EXT, or ft. mm name if desired.) (approx.) APA HIGH DENSITY OVERLAY 4 x 8 1219 x 2438 1.22 x 2.44 Concrete Form: Designate thickness, PLYFORM CLASS I EXT. APA trademark, Class, dimensions, 4 x 9 1219 x 2743 1.22 x 2.74 Use plywood thickness sufficient to number of pieces. For example: support concrete at temperature and 5/8" APA PLYFORM Class I, 4 x 10 1219 x 3048 1.22 x 3.05 rate poured(3); securely brace and shore 48" x 96", 100 pcs. (Plyform panels are forms to prevent displacement and to manufactured only as Exterior panels safely support construction loads. and are mill-oiled unless otherwise specified.) PANEL NOMINAL THICKNESS CSI* Division 6 – in. mm Overlaid Panels: Designate thickness, Wood and Plastics APA trademark, grade, Group number, 1/4 6.4 A. General Provisions dimensions, number of pieces. 5/16 7.9 1. Identification Requirements – For example: 11/32 8.7 Each panel shall be identified with the 1/2" APA MEDIUM DENSITY OVER- 3/8 9.5 appropriate trademark of APA, and shall LAY (MDO) or (APA RATED SIDING meet the requirements of the latest 303-OL in the case of overlaid panels 7/16 11.1 edition of Voluntary Product Standard produced under the APA RATED 15/32 11.9 PS 1, Voluntary Product Standard PS 2 SIDING-303 manufacturing specifi- or APA PRP-108 Performance Standards. cation), Group 1, 48" x 96", 100 pcs. 1/2 12.7 2. All panels which have any edge or (Any special requirements, such as only 19/32 15.1 surface exposed long term to the one side overlaid, surface texture or 5/8 15.9 weather shall be classed Exterior.(4)(5) weight of surfacing material, should be stated after the standard specification.) 23/32 18.3 3. Panel thickness, grade, and Group 3/4 19.1 number or Span Rating shall be at least Grade Availability equal to that shown on the drawings.(6) 7/8 22.2 Some panel grades, thicknesses, Span Application shall be in accordance with Ratings, or species may be difficult to 1 25.4 recommendations of APA.(7) obtain in some areas. Check with your 1-3/32 27.8 supplier for availability or include an *Construction Specifications Institute alternate panel in specifications. 1-1/8 28.6 Standard panel dimensions are four feet by eight feet, although some mills also produce panels nine or ten feet or longer.

12 B. Roof Sheathing roof deck free of dirt, debris and APA RATED SHEATHING EXP 1 1. Panel roof sheathing shall be (specify during construction. Suitable APA RATED SHEATHING EXT appropriate grade): edge support shall be provided where APA STRUCTURAL I RATED indicated on drawings (or in recommen- APA RATED SHEATHING EXP 1 SHEATHING EXP 1, or dations of APA)(6) by use of panel clips, APA RATED SHEATHING EXT tongue-and-groove edges, or lumber APA STRUCTURAL I RATED APA RATED SHEATHING/CEILING blocking between joists. Panel end SHEATHING EXT. DECK EXP 1 joints shall occur over framing. APA STRUCTURAL I RATED APA APA Spacing of 1/8" is recommended THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION SHEATHING EXP 1, or at all panel ends and edges, unless RATED SHEATHING RATED SHEATHING APA STRUCTURAL I RATED otherwise indicated by the panel 24/16 7/16 INCH 40/20 19/32 INCH SIZED FOR SPACING SIZED FOR SPACING manufacturer.(9) EXPOSURE 1 EXTERIOR SHEATHING EXT. 000 000 PRP-108 HUD-UM-40 PS 1-95 C-C PRP-108 6" o.c. along supported panel APA APA edges and 12" o.c. at intermediate THE ENGINEERED THE ENGINEERED Install with the long dimension or WOOD ASSOCIATION WOOD ASSOCIATION supports, except that when supports strength axis of the panel across sup- RATED SHEATHING RATED SHEATHING are spaced 48" o.c. or more, space 32/16 15/32 INCH 48/24 23/32 INCH ports and with panel continuous over SIZED FOR SPACING SIZED FOR SPACING nails 6" o.c. at all supports. Use 8d EXPOSURE 1 EXTERIOR two or more spans. Panel end joints 000 000 common nails, except that when PRP-108 HUD-UM-40 PS 1-95 C-C PRP-108 shall occur over framing. Spacing of panels are 1-1/8", use 8d ring-shank 1/8" is recommended at panel ends Sheathing exposed long term to weather or 10d common.(10)(11)(12) and edges, unless otherwise indicated shall be classed Exterior.(5) Cover roof sheathing as soon as possible by the panel manufacturer.(9) Install with the long dimension or with roofing felt or shingle underlay- Nail 6" o.c. along supported panel edges strength axis of the panel across sup- ment for protection against excessive and 12" o.c. at intermediate supports ports, except where noted(8), and with moisture prior to roofing application. with 6d common nails for panels 1/2" panel continuous over two or more C. Floors or less, 8d for greater thicknesses. spans. For pitched roofs, place 1. Subflooring (under structural finish Where panels are 1-1/8" thick and screened surface or side with skid- floor such as wood strip or underlay- supports are 48" o.c., nails shall be 8d resistant coating up, if OSB panels are ment) – Panel subflooring shall be ring-shank or 10d common and spaced used. Wear skid-resistant shoes when (specify appropriate grade): 6" o.c. at all supports.(10)(11)(12) installing roof sheathing and keep

Notes to Specifiers: (5) Open soffits or roof sheathing exposed on the (9) Supported panel joints shall occur underside may be any panel classed Exposure 1 approximately along the centerline of framing with (1) The APA trademarks shown here are typical where appearance is not a major consideration. a minimum bearing of 1/2". examples only. Refer to the following sections for specific panel grade and thickness (6) Refer to the appropriate application recom- (10) Engineered shear walls and diaphragms may recommendations. mendations in this brochure. require additional nailing. See recommendations in Tables 23 and 32. Diagonal bracing is not (2) Structural I grade (all plies limited to Group 1 (7) References to APA’s recommendations may required for braced wall sections when panel species) can be specified when greater stiffness or allow subsequent specification concerning nailing, wall sheathing, APA RATED WALL BRACING or strength is required. edge support and panel orientation to be omitted. panel siding (APA RATED SIDING) is used.

(3) Thickness recommendations are contained in (8) Long dimension of panel may be parallel (11) Other code-approved fasteners may be used. APA Design/Construction Guide: Concrete Forming, to supports if panel has adequate thickness. Form V345. See Table 27 for roof panels applied parallel (12) Fasteners shall be located 3/8" from panel to supports. edges. (4) Exposure 1 may be specified for applications where temporary exposure to the weather will be (Continued on Page 15) required.

13 PANEL SELECTION AND SPECIFICATION

Sand subfloor joints if necessary to Fill and thoroughly sand edge joints.(14) each other and offset all joints by at least smooth surface prior to installing Lightly sand any surface roughness, two inches from joints in the subfloor underlayment or finish flooring. particularly around fasteners. panels. Butt panel ends and edges to a close but not tight fit (1/32" space is 2. Combined subfloor-underlayment For field-glued floors, use adhesives recommended). Nail 6" o.c. along (under carpet and pad)(13) – Combined meeting APA Specification AFG-01 or panel edges and 8" o.c. each way subfloor-underlayment panels shall be ASTM D3498, applied in accordance throughout remainder of panel with 3d (specify appropriate grade): with the manufacturer’s recommenda- ring-shank nails for panel thicknesses of APA RATED STURD-I-FLOOR tions. If OSB panels with sealed surfaces 11/32" to 1/2", or 4d spaced 6" o.c. EXP 1, or and edges are used, use only solvent- along edges and 12" o.c. each way for based glues; check with panel manufac- APA RATED STURD-I-FLOOR EXT. thicker panels up to 3/4".(11)(17) turer. Apply continuous line of glue Fastener length should be approxi- (1/4" thick) on joists, and continuous or APA APA mately equal to the total thickness of THE ENGINEERED THE ENGINEERED spaced line of glue (1/8" thick) in groove WOOD ASSOCIATION WOOD ASSOCIATION the underlayment and subfloor. of tongue-and-groove panels. Use 6d RATED STURD-I-FLOOR RATED STURD-I-FLOOR 20 oc 19/32 INCH 24 oc 23/32 INCH ring- or screw-shank nails spaced Fill and thoroughly sand edge joints.(14) SIZED FOR SPACING SIZED FOR SPACING T&G NET WIDTH 47-1/2 T&G NET WIDTH 47-1/2 EXTERIOR EXPOSURE 1 12" o.c. at panel ends and intermediate Lightly sand any surface roughness, 000 000 PS 1-95 C-C PLUGGED PRP-108 HUD-UM-40 (10)(15) PRP-108 bearings. particularly around fasteners. 3. Underlayment (over subflooring) – Install with the long dimension or D. Wall Sheathing Plywood underlayment shall be (specify strength axis of the panel across sup- 1. Panel wall sheathing shall be (specify appropriate grade)(16): ports and with panel continuous over appropriate grade): two or more spans. Panel edges shall APA UNDERLAYMENT INT APA RATED SHEATHING EXP 1 be tongue-and-groove or supported on APA UNDERLAYMENT EXP 1 APA RATED SHEATHING EXT 2-inch lumber blocking installed APA UNDERLAYMENT C-C APA STRUCTURAL I RATED between joists. Protect against damage PLUGGED EXT, or SHEATHING EXP 1, until finish floor is installed. APA C-C PLUGGED EXT. APA STRUCTURAL I RATED Stagger panel end joints. Panel end SHEATHING EXT, or joints shall occur over framing. Spacing APA APA of 1/8" is recommended at panel ends THE ENGINEERED THE ENGINEERED APA RATED WALL BRACING EXP 1. WOOD ASSOCIATION WOOD ASSOCIATION and edges, unless otherwise indicated UNDERLAYMENT UNDERLAYMENT by the panel manufacturer.(9) GROUP 1 C-C PLUGGED APA APA GROUP 2 EXPOSURE 1 THE ENGINEERED THE ENGINEERED 000 EXTERIOR WOOD ASSOCIATION WOOD ASSOCIATION For nailed floors, nail panels 6" o.c. at PS 1-95 000 PS 1-95 RATED SHEATHING RATED SHEATHING supported panel edges and 12" o.c. at 24/0 3/8 INCH 32/16 15/32 INCH SIZED FOR SPACING SIZED FOR SPACING intermediate supports, except that when EXPOSURE 1 EXPOSURE 1 When 19/32" or thicker, APA RATED 000 000 STRUCTURAL I RATED PS 1-95 C-D PRP-108 supports are spaced 48" o.c., space nails DIAPHRAGMS-SHEAR WALLS STURD-I-FLOOR EXP 1 or 2 or APA PRP-108 HUD-UM-40 6" o.c. at all supports. Use 6d ring- or RATED STURD-I-FLOOR EXT may be screw-shank nails for panels 3/4" thick Spacing of 1/8" is recommended specified. Apply underlayment just prior or less, and 8d for thicker panels. With at panel ends and edges, unless to laying finish floor and protect against 1-1/8" panels, 10d common nails may otherwise indicated by the panel damage until finish floor is installed. be used if supports are well manufacturer.(9) seasoned.(10)(11)(12) For maximum stiffness, install under- layment with the face grain across sup- ports. Stagger panel end joints (optional under carpet and pad) with respect to

14 Nail 6" o.c. along supported panel Note: Span Ratings and load capacities Plywood shall be all-veneer APA RATED edges and 12" o.c. at intermediate are based on untreated panels, and SHEATHING (or better, depending supports with 6d common nails for may not apply following fire-retardant on appearance desired) EXP 1, marked panels 1/2" and less, and 8d for greater treatment (FRT). Obtain structural APA Series V-600, or EXT, marked APA thicknesses.(10)(12) performance characteristics of FRT Series V-611. Apply building over panel wall panels from the company providing sheathing. the treatment and redrying service. APA APA THE ENGINEERED THE ENGINEERED 2. Preservative-treated plywood – WOOD ASSOCIATION WOOD ASSOCIATION E. Treated Plywood RATED SHEATHING RATED SHEATHING Treated plywood for (state application) 32/16 15/32 INCH 32/16 15/32 INCH 1. Fire-retardant-treated plywood – SIZED FOR SPACING SIZED FOR SPACING shall be pressure-treated in accordance EXTERIOR EXPOSURE 1 000 000 All plywood shall be pressure-treated PS 1-95 C-C PRP-108 PRP-108 HUD-UM-40 with AWPA C9 with (creosote) (penta- APA SERIES V-611 APA SERIES V-600 in accordance with American Wood- chlorophenol) (waterborne) preser- Preservers’ Association Standard AWPA vatives, as required for (coastal water) F. Glued Plywood Components C27 with an approved (low hygro- (wood foundation) (ground contact) scopic, high temperature Interior Type 1. General – All plywood components (above ground) exposure. Plywood shall be fabricated in accordance with A-HT) (Exterior Type) fire retardant. treated with waterborne preservatives Each panel shall be labeled or marked the appropriate APA Fabrication shall be dried after treatment to a mois- Specification.(18) Each original plywood by an approved independent testing ture content of 18 percent or less. agency. After treatment, plywood shall panel shall bear the appropriate trade- All treated plywood used in the be dried to an average moisture content mark of APA. Glue shall be of resorcinol Permanent Wood Foundation System of 15 percent or less. or phenolic resin base (for outdoor (PWF) shall be marked by an approved exposure), or casein with a mold Plywood shall be all-veneer APA RATED inspection agency certified to inspect inhibitor (for indoor exposure). SHEATHING (or better, depending on preservative-treated wood, indicating appearance desired) EXP 1 or EXT. compliance with the treating, drying, retention and penetration requirements APA APA of AWPA Standard C22, or equivalent THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION code-approved preservative-treating and RATED SHEATHING RATED SHEATHING quality control requirements. 32/16 15/32 INCH 48/24 23/32 INCH SIZED FOR SPACING SIZED FOR SPACING EXPOSURE 1 EXTERIOR 000 000 PRP-108 HUD-UM-40 PS 1-95 C-C PRP-108

Notes to Specifiers (Continued): (15) Major model building codes accept 12" “Meets Underlayment Requirements” may also spacing with glue but some local codes may be used under resilient flooring or fully (13) Specify veneer-faced STURD-I-FLOOR with require closer spacing at edges. When panels adhered carpeting. “sanded face” when resilient flooring is to be greater than 3/4" thick are used in glued floors, use same fastener schedule as for nailed-only (17) For 1/4"-thick panels, nail 3" o.c. along panel applied (or see Footnote 16 for additional grades). construction. edges and 6" o.c. each way throughout remainder Otherwise, an additional layer of “sanded face” of panel, with 3d ring-shank nails. underlayment is recommended when resilient (16) For areas to be covered with resilient flooring flooring is to be applied over STURD-I-FLOOR. or fully adhered carpeting, specify Underlayment (18) Design and fabrication specifications for or C-C Plugged panel grades marked “sanded plywood box beams, stressed-skin panels, curved (14) This step may not be necessary under some face.” Underlayment A-C, Underlayment B-C, panels, sandwich panels and all-plywood beams carpet and structural flooring products – check Marine EXT or sanded plywood grades marked are available from APA. with flooring manufacturer. “Plugged Crossbands Under Face,” “Plugged Crossbands (or Core),” “Plugged Inner Plies” or (Continued on Page 17)

15 PANEL SELECTION AND SPECIFICATION

CSI* Division 7 – Thermal B. Soffits Any tree or sap spots shall be and Moisture Protection Soffits shall be (specify appropriate first touched up with a sealer. A. Siding grade):(5) B. Application of Finish Siding shall be (specify appropriate APA A-C EXT (Specify by brush, roller, or spray; grade):(19) APA B-C EXT brush application of the first coat gives APA RATED SIDING EXT, or APA C-C P&TS EXT best performance.) APA MEDIUM DENSITY OVERLAY APA RATED SIDING 303 EXT,(19) or Exterior Panels – Painted (MDO) EXT. First coat: Exterior stain-blocking primer APA MEDIUM DENSITY OVERLAY as recommended by manufacturer of (MDO) EXT.(21) APA APA finish coat. (May be tinted.) Apply THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION Nail 6" o.c. at supported panel edges quantity as recommended by paint RATED SIDING RATED SIDING 303-18-S/W 19/32 INCH and 12" o.c. at intermediate supports, manufacturer. 19/32 INCH 24 oc 16 oc GROUP 1 SIZED FOR SPACING (20) SIZED FOR SPACING with 6d nonstaining box, casing, or EXTERIOR EXTERIOR Second coat: Top-quality exterior all- T1-11 000 000 PRP-108 HUD-UM-40 siding nails for panels 1/2" and less, and PS 1-95 PRP-108 FHA-UM-40 acrylic latex house paint designed for 8d for thicker panels up to 3/4". use with primer; color as selected. Two Spacing of 1/8" is recommended at topcoats provide better performance. panel ends and edges, unless other- APA APA THE ENGINEERED THE ENGINEERED Exterior Panels – Stained wise indicated by the panel manufac- WOOD ASSOCIATION WOOD ASSOCIATION First coat: Top-quality exterior pene- turer. Nail panel siding 6" o.c. along RATED SIDING 303-18-S/W A-C GROUP 1 11/32 INCH trating semitransparent oil stain where GROUP 1 panel edges and 12" o.c. at intermediate 16 oc EXTERIOR SIZED FOR SPACING grain showthrough is desired(22); or (20) EXTERIOR 000 supports with 6d nonstaining box, 000 PS 1-95 PS 1-95 PRP-108 heavily pigmented solid-color oil or latex casing or siding nails for panels 1/2" and FHA-UM-40 stain where grain is to be masked(23); less, and 8d for greater thicknesses.(10) color as selected. Apply in one or two CSI* Division 9 – Nail lap siding installed over nailable coats as recommended by manufacturer. Finishes (Painting)(19) panel or lumber sheathing 8" o.c. along Use stain-blocking primer with light- bottom edge, unless otherwise recom- A. Preparation of Surfaces colored solid-color latex stains. mended by manufacturer. Nail lap sid- 1. Exterior Panels – Panels to be ing installed direct to studs or over exposed outdoors shall have all edges Interior Panels – Painted nonstructural sheathing at each stud. sealed. With paint, sealer may be a First coat: Stain-blocking primer as Use 6d nonstaining(20) box, casing, or liberal coat of exterior house paint recommended by manufacturer of siding nails for siding 1/2" thick, and 8d primer. With stain, seal with water- finish coat. for thicker panels. If siding is applied repellent preservative compatible Second coat: Flat, semi-gloss or gloss over nonstructural sheathing, use next with finish coat. topcoat designed for use with primer; regular nail size. Use nonstaining box Surface shall be clean, dry and free of color as selected. Use two topcoats if nails for siding installed over foam loose wood fibers. needed to cover. insulation sheathing. 2. Interior Panels – Surface shall be Interior Panels – Color Tone Prior to installing siding, apply building clean, dry and free of loose wood fibers. First coat: Stain and companion sealer paper over studs or sheathing.(6) Holes and cracks shall be filled with mixed to selected color (or sealer, then All panel edges should be sealed. For putty or plastic wood (except for rustic stain applied separately). panels to be painted, sealer can be paint type panels intended for stain finish). Second coat: Interior satin primer; for panels to be stained, sealer After dry, sand lightly in the direction of (additional coats can be applied as should be a water-repellent preservative the grain of face veneer or texture to desired for depth of luster). compatible with the finish. match existing surfaces. *Construction Specifications Institute

16 Interior Panels – Light Stain PANEL STORAGE Cover the stack loosely with plastic First coat: Pigmented resin sealer (wiped AND HANDLING sheets or tarps. Anchor the covering at off when tacky). Like all building materials, APA the top of the stack, but keep it open Second coat: Clear resin sealer. trademarked structural wood panels and away from the sides and bottom to assure good ventilation. Tight coverings Third coat: Tinted undercoat; thin should be properly stored, handled prevent air circulation and, when enamel; pigmented sealer; or light stain and installed to assure superior exposed to sunlight, create a “green- applied thinly and wiped to the desired in-service performance. house” effect which may encourage color depth; color as selected. Protect the edges and ends of panels, mold formation. Fourth coat: Interior satin varnish (addi- especially tongue-and-groove and tional coats can be applied as desired for -edged panels. Place panels depth of luster). to be moved by forklift on pallets or PANEL STORAGE bunks when received to avoid damage Build platform of cull panel and scrap by fork tines. lumber 4x4s for stacking panels. Panels to be transported on open truck beds should be covered with standard tarpaulins. For open railcar shipment, use “lumber wrap” to avoid extended weather exposure. Stretch plastic film over platform to block passage of ground moisture. Notes to Specifiers (Continued): Store panels whenever possible (19) See APA Product Guide: Performance Rated Sidings, E300. under a roof, especially if they won’t be used soon after received. Keep sanded (20) Hot-dipped or hot-tumbled galvanized steel nails are recommended for most siding and other appearance grades away applications. For best performance, stainless steel nails or aluminum nails should be from open doorways, and weight down considered. APA tests also show that electri- the top panel in a stack to help avoid cally or mechanically galvanized steel nails appear satisfactory when plating meets or any possible warpage from humidity. If Nail film to top panel and drape over exceeds thickness requirements of ASTM ends for protection against driving A641 Class 2 coatings, and is further moisture absorption is expected, cut rain. Weight lower end with 2x4. protected by yellow chromate coating. steel banding on panel bundles to Note: Galvanized fasteners may react under prevent edge damage. Lay two 2x4s on top of stack. wet conditions with the natural extractives Pad corners with rags. of some wood species and may cause Panels to be stored outside should be staining if left unfinished. Such staining can be minimized if the siding is finished stacked on a level platform supported in accordance with APA recommendations, by 4x4 stringers or other blocking. or if the roof overhang protects the siding from direct exposure to moisture and Never leave panels or the platform in weathering. direct contact with the ground. Use at (21) Specify MDO plywood with one face of least three full-width supports along the Medium Density Overlay as described in Voluntary Product Standard PS 1. eight-foot length of the panel – one Stretch film over stack and secure to tie-down stakes. (22) Semitransparent stains may be used on centered and the others 12 to 16 inches plywood face grades 303-OC, 303-NR and from each end. 303-6-W. Other 303 face grades should not be finished with semitransparent stains unless specifically recommended by the panel manufacturer.

(23) Only latex formulations are recom- mended on APA 303-SR and 303-NR grades of plywood siding.

17 GLULAM SELECTION AND SPECIFICATION

A glulam is made up of wood lamina- “TOP.” Unbalanced beams are primarily Sizes tions, or “lams” that are bonded intended for simple span applications. Glulam is available in both custom and together with adhesives. The grain of all Balanced members are symmetrical in stock sizes. Stock beams are manufac- laminations runs parallel with the length lumber quality about the mid-height. tured in commonly used dimensions and of the member. Individual lams typically Balanced beams are used in applications cut to length when the beam is ordered are 1-3/8 inches thick for southern such as cantilevers or continuous spans, from a distributor or dealer. Typical stock and 1-1/2 inches thick for Western where either the top or bottom of the beam widths include: 3-1/8", 3-1/2", species, although other thicknesses may member may be stressed in tension due 5-1/8", 5-1/2", and 6-3/4". also be used. Glulam products typically to service loads. They can also be used Where long spans, unusually heavy range in net widths from 2-1/2 to in single span applications, although an loads, or other circumstances control 10-3/4 inches although virtually any unbalanced beam is more efficient for design, custom members are typically width can be custom produced. this use. specified. Common custom shapes include curved beams, pitched and Balanced and Unbalanced Beams Allowable Design Properties curved beams, radial arches and Glulam may be manufactured as Allowable design properties are a key tudor arches. unbalanced or balanced members. factor in specifying glulam. Bending The most critical zone of a glulam bend- members are typically specified on the Appearance Classification ing member with respect to controlling basis of the maximum allowable bending Glulam is available in a range of appear- strength is the outermost tension zone. stress of the member. For example, a 24F ances, all looking different but having In unbalanced beams, the quality of designation indicates a member with an the same structural characteristics for a lumber used on the tension side of the allowable bending stress of 2400 psi. given strength grade. Glulam appear- beam is higher than the lumber used on Similarly, a 20F designation refers to a ance classifications are: the corresponding compression side, member with an allowable bending Framing. An EWS classification that allowing a more efficient use of the stress of 2000 psi. These different stress denotes the member is intended only timber resource. Therefore, unbalanced levels are achieved by varying the species for use in concealed applications. Beams beams have different bending stresses and percentages and grade of higher with this appearance classification are assigned to the compression and ten- quality lumber in the beam layup. provided in widths designed to fit flush sion zones and must be installed To identify whether the lumber used in with 2x4 and 2x6 wall framing. accordingly. To assure proper installation the beam is visually or mechanically Industrial. Used for concealed applica- of unbalanced beams, the top of the graded, the stress combination also tions or where appearance is not of beam is clearly stamped with the word includes a second set of designations. primary importance. For example, for an unbalanced 24F Architectural. The appearance of choice layup using visually graded lumber, the STANDARD BEAM LAYUP in applications where members are layup designation may be identified as a exposed to view, because they have a Compression 24F-V4. The “V” indicates that the lam at top smooth, attractive finish. Stock beams layup uses visually graded lumber. (“E” are often supplied with this appearance is used for mechanically graded lumber.) so they may be exposed to view in the The number “4” further indicates a finished structure. Core lams specific combination of lumber used to in center which a full set of design stresses such Premium. Available only as a custom as horizontal shear, MOE, etc., are order where finished appearance is of assigned. See also Engineered Wood primary importance. Systems Data File: Glulam Design Tension lam at bottom Properties and Layup Combinations, Form EWS Y117.

18 All appearance classifications permit natural growth characteristics with vary- TABLE 5 ing degrees of open voids permitted. CAMBER FOR 3,500-FOOT RADIUS Voids are filled as required by the appear- Span in feet: 10 12 14 16 18 20 22 24 26 28 ance grade specified using inserts and Camber in inches: .04 .06 .08 .11 .14 .17 .21 .25 .29 .34 wood fillers. The appearance classifica- tion is not related to lumber layup requirements and thus does not affect The glulam industry recommends that Most residential applications require design values for the beam. For addi- roof beams be cambered for 1-1/2 times very little or no camber which, in turn, tional information, refer to Engineered the calculated dead load deflection. This makes glulam the ideal choice. Stock Wood Systems Technical Note: Glued will generally be sufficient to assure that beams are typically supplied with a Laminated Timber Appearance the beam will not exhibit a sag over a relatively flat camber radius of 3,500 feet Classifications for Construction Applications, period of many years of loading, as may as shown in Table 5, or zero camber. Form EWS Y110. occur with non-cambered wood prod- Thus, they have just the right camber for ucts. To achieve a level profile it is rec- residential construction. If, however, Section Properties and Capacities ommended that floor beams be only more camber is required, such as for a When selecting a glulam member, the cambered for 1.0 times the calculated long span roof beam, custom beams are builder, designer, or specifier must use dead load deflection. available through manufacturers to meet a member with the required section Camber for glulam beams is specified as the most exacting specifications. properties to satisfy the load carrying either “inches of camber” or as a radius For additional information on cambering requirements. Different load capacities of curvature that is to be used in the glulam beams, refer to Engineered Wood are possible for different stress level manufacturing process. Commonly Systems Technical Note: Glulam Beam combinations of glulam. Tables giving used curvature radii for commercial Camber, Form EWS S550, which pro- the load carrying capacities for glulam applications are 1,600 and 2,000 feet vides a camber table for various beam are included in the Engineered Wood although any camber may be specified. spans and radii of curvature. Systems Data File: Glued Laminated Beam Design Tables, Form EWS S475.

Camber Camber is curvature built into a fabri- cated member (see figure below) which 1 B IND EWS Y117 4 is opposite in direction and magnitude 6 7 to the calculated deflection which will EWS 24F-1.8E WW 5 occur under gravity loads. 2 MILL 0000 ANSI A190.1-1992 3

BEAM CAMBER PARAMETERS 1 Indicates structural use: B-Simple span bending member. C-Compression member. T-Tension member. CB-Continuous or cantilevered span bending member. 2 Mill number. L = Span (ft.) 3 Identification of ANSI Standard A190.1, Structural . ANSI A190.1 is the American National Standard for glulam beams. 4 Applicable laminating specification. Cambered beam 5 Western (see note 6). 6 Structural grade designation. The APA EWS 24F-1.8E designation is a glulam grade commonly ∆ used in residential applications. Combining a group of six layup combinations made with Douglas = Camber (in.) fir-larch, -pine-fir, southern pine, and/or hem-fir, this grade provides strength (allowable bending stress of 2,400 psi and allowable shear stress of 155 psi) and stiffness (modulus of elasticity of 1.8 x 106 psi) needed for typical residential applications, while greatly simplifying R = Radius of curvature (ft.) the design specification. 7 Designation of appearance grade. INDUSTRIAL, ARCHITECTURAL, PREMIUM, or FRAMING.

19 GLULAM SELECTION AND SPECIFICATION

Trademarks and Acceptances SPECIFICATION GUIDE connections shall be finished with one Glulam beams manufactured by FOR STRUCTURAL GLUED coat of rust-inhibiting paint. Engineered Wood Systems members LAMINATED TIMBER (GLULAM) B. Manufacture are certified with the APA EWS trade- 1. Materials, Manufacture and Quality mark. The mark (as shown) signifies A. General Assurance – Structural glued laminated that the manufacturer is committed to a 1. Structural glued laminated timber timber of species shall be in rigorous program of quality verification shall be furnished as shown on the conformance with ANSI Standard and testing and that products are plans and in accordance with the fol- A190.1, American National Standard manufactured in conformance with lowing specifications. (Where other uses for Structural Glued Laminated ANSI Standard A190.1-92, American or requirements are applicable, modify Timber, or other code-approved National Standard for Structural specifications accordingly.) design, manufacturing and/or quality Glued Laminated Timber. The APA EWS 2. Shop drawings and details shall be assurance procedures. trademark is recognized by all major furnished by the (manufacturer) (seller) model building codes. and approval obtained from the (archi- 2. End-Use Application – Structural glued laminated timber members shall Typical information included in an tect) (engineer) (general contractor) be manufactured for the following struc- APA EWS trademark is shown on the (buyer) before fabrication is tural uses as applicable: (Simple span sample trademark on page 19. This commenced. bending member – B) (continuous or information may vary depending on 3. The (manufacturer) (seller) (general cantilever span bending member – CB) whether the member is supplied as a contractor) shall furnish connection (compression member – C) (tension custom or stock product. steel and hardware for joining structural member – T). glued laminated timber members to each other and to their supports, exclu- 3. Design Values – Structural glued sive of anchorage embedded in masonry laminated timber shall provide design or concrete, setting plates, and items values for normal load duration and (1)(2) field-welded to structural steel. Steel dry-use condition.

Notes to Specifiers: Description: Glulam members manufactured to the member in any glueline. The frequency of be compatible with these dimensions are finished occurrence shall not exceed one in ten pieces of (1) Dry service condition – moisture content of to what are referred to in the industry as “hit or lumber used. The maximum area of low lamina- the member will be at or below 16% in service; miss” surfacing. Surface characteristics of glulam tions shall not exceed 25% of the surface area of a wet service condition – moisture content of the members finished to this classification include: side. Permissible wane in accordance with the member will be above 16% in service. When provisions of the layup combination is not limited structural glued laminated timber members are Manufacturing characteristics including low in length. to be preservative treated, wet-use adhesives laminations, glue smear, end joint offsets and must be specified. glueline squeezeout are permitted. INDUSTRIAL. Use where appearance is not of primary importance, or where members are not (2) An alternative to specifying the required Lumber characteristics permitted for the given exposed visually. design stresses is to specify a specific laminating layup combination may include knot holes, splits combination symbol if known to be available. and wane. Description: Natural lumber growth characteris- tics may be visible. Voids on edges of laminations (3) Appearance classifications are described as Voids appearing on the edge of laminations need may not be filled, except loose knots and knot- follows. For further information, see Engineered not be filled. holes may be filled in some applications. Wood Systems Technical Note EWS Y110, Glued Laminated Timber Appearance Classifications for Loose knots and knot holes appearing on the ARCHITECTURAL. Use where appearance Construction Applications. wide face of the laminations exposed to view need is important. not be filled. FRAMING. The Framing appearance classification Description: Natural lumber growth characteris- is a new classification introduced by the industry Members are required to be surfaced “hit or miss” tics may be visible. Knotholes and voids larger to accommodate home building and other con- on two sides only and the appearance require- than 3/4" are filled or repaired with wood inserts. struction markets where glulam is used in combi- ments apply only to these sides. Exposed faces are surfaced smooth and exposed nation with dimension lumber in roof, wall and edges are eased (chamfered). floor framing. To be compatible with the conven- Wane (limited to a maximum of 1/4 inch mea- tional framing lumber sizes without the need for sured across the width) is permitted on a cumula- PREMIUM. Use where highest-quality visual furring or other specialized framing, glulam is tive basis. The accumulative depth of hit and miss appearance is required. supplied in 3-1/2, 5-1/2 and 7-1/4-inch widths. and wane shall not exceed 10% of the width of

20 7. Preservative Treatment unloading and transporting as well (when applicable) – (Beams) as in the yard and on the job site. (Columns) shall be pressure treated Sealants on the ends of beams help after manufacture in accordance guard against moisture penetration and with American Wood-Preservers’ checking. Apply a coat of sealant to the Association (AWPA) Standard C28 ends of beams after trimming. Surface with (creosote or creosote/coal tar sealants, which can be applied to the solution) (pentachlorophenol in oil) top, bottom and sides of beams, resist (pentachlorophenol in light solvent) dirt and moisture and help control preservatives as required for (soil checking and grain raising. Use a pene- contact) (above ground) exposure. trating sealant if beams will be stained 8. Fire Resistance (when applicable) – or given a natural finish. 4. Appearance Grade – (Beams) (Beams) (Columns) shall be sized A primer coat also protects beams from (Columns) shall be (framing) (industrial) and manufactured for one-hour fire moisture and dirt and provides a (3) (4) (architectural) (premium) grade in resistance. paintable surface. accordance with ANSI Standard A190.1. 9. Protective Sealers and Finishes – Water-resistant wrappings are another 5. Laminating Adhesives – Adhesives Unless otherwise specified, sealer shall way to protect beams from moisture, used in the manufacture of structural be applied to the ends of all members. dirt and scratches. Because sunlight glued laminated timber shall meet Surfaces of members shall be (not can discolor beams, opaque wrappings requirements for (wet-use) (dry-use) sealed) (sealed with penetrating sealer) are recommended. Beams can be (1) (5) service conditions. (sealed with primer/sealer coating). wrapped individually, by the bundle 6. Camber (when applicable) – 10. Trademarks – Members shall be or by the load. In situations where Structural glued laminated timber (shall) marked with the Engineered Wood appearance is especially important, (shall not) be manufactured with a Systems APA EWS trademark indicating the wrapping can be removed after built-in camber. conformance with the manufacturing, installation to avoid damage. quality assurance and marking provi- If possible, store glulam under cover sions of ANSI Standard A190.1. to protect them from rain and sunlight. 11. Certificates (when applicable) – Place the beams on spaced lumber Description: Natural lumber growth charac- A Certificate of Conformance shall be bunks on level, well-drained ground. In teristics may be visible. All knotholes and provided by the (manufacturer) (seller) some instances, the wrappings can be voids are filled or repaired with wood inserts. Exposed surface of wide face lamina- to indicate conformance with ANSI used to protect beams until installation. tion has limit on knot size and no loose knots. Exposed faces are surfaced smooth, Standard A190.1. Again, seal ends of beams immediately and exposed edges are eased. 12. Protection for Shipment – after trimming. Once beams are (4) When structural glued laminated timber installed, allow them to gradually season with one-hour fire resistance is specified, Members shall be (not wrapped) (load minimum size limitations and additional wrapped) (bundle wrapped) (individu- and adjust to the temperature and mois- lamination requirements are applicable. ture conditions of the structure. Supporting steel connectors and fasteners ally wrapped) with a water-resistant also must be protected to achieve a one- covering for shipment. hour fire rating. Cover with fire-rated (Type X) gypsum wallboard or sheathing, or 1-1/2" GLULAM BEAM STORAGE wood, to provide the needed protection. See page 62. GLULAM BEAM STORAGE Beams (5) Specify a penetrating sealer when the AND HANDLING finish will be natural or a semitransparent stain. Primer/sealer coatings have a higher APA EWS trademarked glued laminated solids content and provide greater moisture protection, and are suitable for use with beams (glulam) are commonly opaque or solid-color finishes. protected with sealants, primers or Cut drainage holes in bottom Lumber bunks wrappings when they leave the mill. But of wrapping or skids care must be taken during loading,

21 I-JOIST SELECTION AND SPECIFICATION

The APA Performance Rated I-Joist (PRI) APA PRIs are available in four depths: Residential Floor Spans is an “I”-shaped engineered wood struc- 9-1/2, 11-7/8, 14, and 16 inches. Some APA PRIs include in their trade- tural member designed for use in resi- Most manufacturers supply I-joists to marks allowable spans for uniformly dential floor construction. The product distributors and dealers in lengths up to loaded residential floor construction at is prefabricated using sawn or structural 60 feet. These are then cut to frequently various I-joist spacings. Therefore, the flanges and plywood used lengths such as 16 to 36 feet. specific I-joist needed is easily deter- or OSB webs, bonded together with Check local supplier for availability. mined by selecting the span and then exterior type adhesives. In order to be choosing the I-joist that meets the span, classified as an APA PRI, the joist is APA PRI-400 spacing, and loading criteria. See Tables limited to a L/480 live load maximum APA PRIs are manufactured in accor- 6 and 7. dance with Performance Standard for APA deflection (where L = span) for glued- For more information on selecting EWS I-Joists, PRI-400. This Performance nailed residential floor applications, a APA I-joists, and for design tables, Standard provides an easy-to-use table criteria which provides superior floor refer to the APA Design/Construction of allowable spans for applications in performance. Guide: I-Joists for Residential Floors, residential floor construction, allowing APA Performance Rated I-joists are Form X710. identifed by their net depth followed by designers and builders to select and use a designation such as PRI-30 which I-joists from various member manufac- relates to the joist strength and stiffness. turers using just one set of span tables.

SAMPLE TRADEMARK (Position of trademark on I-joist may vary by manufacturer)

The I-joist alternative to Identifies I-joists as being Joist designation The on-center spacing 2 x 10 lumber with a net manufactured in confor- of the I-joists (optional information) depth of 9-1/2". Also mance with APA Standard available in 11-7/8", PRI-400, Performance 14", and 16" Standard for APA EWS I-Joists

TM SPACING 12 16 19.2 24 SIMPLE SPAN 18-0 16-6 15-7 14-1 Glued Residential Floors 9-1/2" PR 40 MULTIPLE SPAN 19-7 17-2 15-8 14-0 PLANT 0000 • PRI-400

The residential floor clear span that Plant number Conforms with APA can be achieved for a glued-nailed Standard PRI-400, floor system at the indicated spacing Performance for a live load of 40 psf and a dead Standard for APA load of 10 psf (optional information) EWS I-Joists

22 SPECIFYING APA PERFORMANCE RATED TABLE 6 I-JOISTS ALLOWABLE SPANS FOR APA EWS PERFORMANCE RATED I-JOISTS – The following is a guide for specifying Simple Span Only APA Performance Rated I-Joists (PRI) Simple Spans to be used in residential floor applica- Joist On Center Spacing tions. These structural products are Depth Designation 12" 16" 19.2" 24" available in net depths of 9-1/2 inches, PRI-20 16'-7" 15'-2" 14'-4" 13'-4" PRI-30 17'-1" 15'-8" 14'-10" 13'-11" 11-7/8 inches, 14 inches, and 9-1/2" PRI-40 18'-0" 16'-6" 15'-7" 14'-1" 16 inches, and can be used for simple- PRI-50 17'-10" 16'-4" 15'-5" 14'-5" PRI-60 19'-0" 17'-4" 16'-4" 15'-4" or multiple-span floor construction with PRI-20 19'-11" 18'-2" 17'-2" 15'-5" a design live load of 40 psf and dead PRI-30 20'-6" 18'-9" 17'-9" 16'-7" load of 10 psf or 20 psf as applicable. PRI-40 21'-6" 19'-7" 18'-2" 16'-3" 11-7/8" PRI-50 21'-4" 19'-6" 18'-5" 17'-3" Exterior use, or use of wood I-joists PRI-60 22'-8" 20'-8" 19'-6" 18'-3" in other than protected dry conditions, PRI-70 23'-0" 21'-0" 19'-10" 18'-7" is not recommended. PRI-80 24'-11" 22'-8" 21-4" 19'-11" PRI-40 24'-4" 22'-1" 20'-2" 18'-0" A. General PRI-50 24'-4" 22'-3" 21'-0" 19'-8" 14" PRI-60 25'-9" 23'-6" 22'-2" 20'-9" 1. APA PRIs shall be furnished and PRI-70 26'-1" 23'-10" 22'-6" 21'-0" installed as shown by the approved PRI-80 28'-3" 25'-9" 24'-3" 22'-8" building plans and installation PRI-40 27'-0" 24'-0" 21'-11" 19'-7" PRI-50 27'-0" 24'-8" 23'-4" 20'-2" instructions. 16" PRI-60 28'-7" 26'-1" 24'-7" 23'-0" 2. The designation of APA PRI shall be PRI-70 29'-0" 26'-5" 24'-11" 23'-1" PRI-80 31'-4" 28'-6" 26'-11" 25'-1" based on the applicable loading, joist Notes: spacing and spans shown in the plans. 1. Allowable clear span applicable to simple-span residential floor construction with a design dead load of 10 psf and live load of 40 psf. See Table A2 for applications carrying a live load of 40 psf PRIs may be selected using Tables 2 and and dead load of 20 psf. The live load deflection is limited to span/480. 2. Spans are based on a composite floor with glued-nailed sheathing meeting the requirements for 3 of the APA Design/Construction Guide: APA Rated Sheathing or APA Rated STURD-I-FLOOR conforming to PRP-108, PS 1, or PS 2 with a minimum thickness of 19/32 inch (40/20 or 20 oc) for a joist spacing of 19.2 inches or less, or I-Joists for Residential Floors, Form X710. 23/32 inch (48/24 or 24 oc) for a joist spacing of 24 inches. Adhesive shall meet APA Specification For non-uniform loading conditions AFG-01 or ASTM D3498. Spans shall be reduced 1 foot when the floor sheathing is nailed only. 3. Minimum bearing length shall be 1-3/4 inches for the end bearings. requiring an engineering analysis, see 4. Bearing stiffeners are not required when I-joists are used with the spans and spacings given in this Table A1 from the above-mentioned table, except as discussed on page 21 of this design guide for hangers. 5. This span chart is based on uniform loads. For applications with other than uniformly distributed guide for PRI joist properties. loads, an engineering analysis may be required based on the use of the design properties in Table A1. The specification for I-joists required for a specific floor application shall include joist depth, designation, length, and 4. APA EWS trademarked glued- 5. The contractor shall use approved number of pieces required. laminated timber (glulam) or approved connection hardware (joist hangers) as structural composite lumber (SCL) shall specified in the plans. Such hardware Example: 21 pieces – be furnished for load-bearing joist head- shall be compatible with the width and APA 9-1/2" PRI-30 x 30 feet long ers. The depth of these components depth of APA PRIs furnished, to provide 3. All accessory products such as I-joist shall be specified to match the I-joist flush nailing surfaces at adjoining mem- blocking panels, rim boards, squash depth when flush framing is required. bers and to prevent rotation. blocks, web stiffeners, etc., shall be provided and installed in accordance with the applicable installation details shown in this guide.

23 I-JOIST SELECTION AND SPECIFICATION

B. Manufacture 1. Materials, Manufacture, and TABLE 7 Quality Assurance. Product quality shall ALLOWABLE SPANS FOR APA EWS PERFORMANCE RATED I-JOISTS – conform to the manufacturer’s approved Multiple Span Only Multiple Spans quality control manual, with compliance On Center Spacing assurance services provided by APA in Joist Depth Designation 12" 16" 19.2" 24" accordance with building code require- PRI-20 18'-1" 16'-3" 14'-10" 13'-3" ments and the applicable code evalua- PRI-30 18'-8" 17'-1" 16'-1" 15'-0" tion report. 9-1/2" PRI-40 19'-7" 17'-2" 15'-8" 14'-0" PRI-50 19'-5" 17'-9" 16'-9" 15'-8" 2. Trademarks. I-joists shall be marked PRI-60 20'-8" 18'-10" 17'-9" 16'-5" with the APA PRI trademark indicating PRI-20 21'-8" 18'-10" 16'-9" 13'-5" PRI-30 22'-4" 20'-5" 18'-10" 15'-0" conformance with the manufacturing, PRI-40 23'-0" 19'-11" 18'-2" 16'-2" quality assurance, and marking provi- 11-7/8" PRI-50 23'-3" 21'-3" 20'-0" 16'-1" sions of APA EWS Standard PRI-400, PRI-60 24'-8" 22'-6" 21'-2" 19'-1" PRI-70 25'-1" 22'-11" 21'-7" 18'-6" Performance Standard for APA EWS I-Joists. PRI-80 27'-1" 24'-8" 23'-3" 21'-8" 3. Jobsite Shipment. I-joists shall be PRI-40 25'-6" 22'-1" 20'-1" 18'-0" PRI-50 26'-6" 24'-2" 20'-2" 16'-1" protected from direct exposure to 14" PRI-60 28'-1" 25'-7" 23'-8" 19'-9" weather prior to installation. PRI-70 28'-6" 25'-11" 23'-2" 18'-6" PRI-80 30'-10" 28'-0" 26'-5" 23'-11" PRI-40 27'-8" 23'-11" 21-10" 19'-6" PRI-50 29'-6" 24'-3" 20'-2" 16'-1" 16" PRI-60 31'-2" 28'-1" 24'-9" 19'-9" PRI-70 31'-7" 27'-10" 23'-2" 18'-6" PRI-80 34'-2" 31'-1" 29'-3" 23'-11" Notes: 1. Allowable clear span applicable to multiple-span residential floor construction with a design dead load of 10 psf and live load of 40 psf. See Table A2 for applications carrying a live load of 40 psf and dead load of 20 psf. The end span shall be 40% or more of the adjacent span. The live load deflec- tion is limited to span/480. 2. Spans are based on a composite floor with glued-nailed sheathing meeting the requirements for APA Rated Sheathing or APA Rated STURD-I-FLOOR conforming to PRP-108, PS 1, or PS 2 with a minimum thickness of 19/32 inch (40/20 or 20 oc) for a joist spacing of 19.2 inches or less, or 23/32 inch (48/24 or 24 oc) for a joist spacing of 24 inches. Adhesive shall meet APA Specification AFG-01 or ASTM D3498. Spans shall be reduced 1 foot when the floor sheathing is nailed only. 3. Minimum bearing length shall be 1-3/4 inches for the end bearings, and 3-1/2 inches for the intermediate bearings. 4. Bearing stiffeners are not required when I-joists are used with the spans and spacings given in this table, except as discussed on page 21 of this design guide for hangers. 5. This span chart is based on uniform loads. For applications with other than uniformly distributed loads, an engineering analysis may be required based on the use of the design properties in Table A1.

24 I-JOIST STORAGE I-joists are not stable until completely AND HANDLING installed, and will not carry any load Store, stack and handle I-joists verti- until fully braced and sheathed. Do not cally, and try to keep joists level. Do not allow workers to walk on joists until the store I-joists in direct contact with the joists are fully installed and braced. To ground. Protect I-joists from weather, avoid accidents, brace and nail each and use stickers to separate the bun- I-joist as it is installed, using hangers, dles. If I-joists are delivered wrapped, blocking panels, rim board, and/or do not open bundles until time of cross-bridging at joist ends and over installation. each support. When handling I-joists with a crane on the job site (“picking”), take a few simple precautions to prevent damage to the joists and injury to the work crew: pick I-joists in bundles as shipped by the supplier; orient the bundles so that the webs of the I-joists are vertical; and pick the bundles at the fifth points, using a spreader bar if necessary. Do not twist or apply loads to the I-joists when they are horizontal. Never use or try to repair a damaged I-joist.

L 5

L

L 5

25 FLOOR CONSTRUCTION

APA Rated Sturd-I-Floor® Standards and/or Voluntary Product APA RATED STURD-I-FLOOR is a span- Standard PS 1 or PS 2. And it’s easy to rated APA proprietary product designed use and specify because the maximum specifically for use in single-layer floor recommended spacing of floor joists – construction beneath carpet and pad. or Span Rating – is stamped on each The product provides all of the proven panel. Panels are manufactured with cost-saving and performance benefits of Span Ratings of 16, 20, 24, 32 and combined subfloor-underlayment con- 48 inches. These assume use of the struction. It is manufactured in confor- panel continuous over two or more mance with APA PRP-108 Performance spans with the long dimension or strength axis across supports.* APA APA Glue-nailing is recommended for THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION STURD-I-FLOOR panels, though panels RATED STURD-I-FLOOR RATED STURD-I-FLOOR may be nailed only. Recommendations 24 oc 23/32 INCH 20 oc 19/32 INCH SIZED FOR SPACING SIZED FOR SPACING T&G NET WIDTH 47-1/2 T&G NET WIDTH 47-1/2 for both methods are given in Table 8. EXPOSURE 1 EXPOSURE 1 000 000 PS 1-95 UNDERLAYMENT PRP-108 HUD-UM-40 (See “The APA Glued Floor System,” PRP-108 page 30, for more detailed gluing recommendations.) Always protect APA smooth panel faces and tongue-and- THE ENGINEERED WOOD ASSOCIATION groove edges from damage prior to and RATED STURD-I-FLOOR during application. Install with smooth 20 oc 19/32 INCH SIZED FOR SPACING T&G NET WIDTH 47-1/2 side up. Recommended live loads are EXPOSURE 1 000 PS 2-92 SINGLE FLOOR given in Table 9. PRP-108 HUD-UM-40

FIGURE 1 APA RATED STURD-I-FLOOR 16, 20, AND 24 oc

Stagger end joints Blocking with square edge panels APA RATED STURD-I-FLOOR 16, 20, 24 oc 2x joists, I-joists or floor 16", 19.2", or 24" o.c.

Carpet Strength axis and pad

2x rim joist or APA Rim Board Note: Provide adequate ventilation and 1/8" spacing is use ground cover vapor retarder recommended at all edge in crawl space. Panels must be dry before applying finish floor. and end joints unless Note: otherwise indicated by For buildings with wood or steel framed walls, panel manufacturer provide 3/4" expansion joints with separate floor framing members and discontinuous wall plates Tongue-and-groove edges over the joints, at intervals that limit continuous floor areas to 80 feet maximum in length or (or 2" lumber blocking width, to allow for accumulated expansion during between supports) construction in wet weather conditions.

26 If long-term exposure to the weather is required, specify Exterior panels. FIGURE 2 APA RATED STURD-I-FLOOR 32 AND 48 oc Although STURD-I-FLOOR is suitable (Over Supports 32"o.c.) for direct application of carpet and pad, an additional thin layer of underlayment APA RATED 1/8" spacing is recommended at all edge and end joints STURD-I-FLOOR unless otherwise indicated by panel manufacturer is recommended under tile, sheet floor- 32 oc or 48 oc ing or fully adhered carpet. This added Stagger end joints layer restores a smooth surface over T&G joint panels that may have been scuffed or (or block edges) Strength axis roughened during construction, or over panels that may not have received a 2x sill sufficiently sanded surface. When 2x rim joist veneer-faced STURD-I-FLOOR with or APA “sanded face” is specified, the surface is Rim Board Center girder also suitable for direct application of Note: Provide adequate ventilation and Joists 32" o.c. (2x10s typical) resilient floor covering. Glued T&G use ground cover vapor retarder in crawl space. Panels must be dry edges are recommended under thin before applying finish floor. Framing anchors (or 2x2 ledger) floor coverings to assure snug joints. Note: For buildings with wood or steel framed walls, provide 3/4" expansion joints with separate floor If the floor has become wet during framing members and discontinuous wall plates over the joints, at intervals that limit continuous floor areas to 80 feet maximum in length or width, to allow for accumulated expansion during construction construction, it should be allowed to in wet weather conditions. dry before application of finish floor, including carpet, underlayment, hard- , ceramic tile, etc. After it is dry, the floor should be checked for FIGURE 3 flatness, especially at joints. APA RATED STURD-I-FLOOR 48 oc When floor members are dry, make sure (Over Supports 48" o.c.) fasteners are flush with or below surface 1/8" spacing is recommended at all edge and end of the STURD-I-FLOOR panels just joints unless otherwise indicated by panel manufacturer prior to installation of thin floor cover- APA RATED Stagger end joints ings. Fasteners should be set if green STURD-I-FLOOR 48 oc Girder framing will present nail popping prob- lems upon drying. Do not fill nail holes. Strength axis Fill and thoroughly sand edge joints (this step may not be necessary under 2x sill some carpet and structural flooring 12" 2x rim joist or min. products – check recommendations of APA Rim Board flooring manufacturer). Fill any other T&G joint damaged or open areas, such as splits, (or block edges) 4x4 and sand all surface roughness. Note: Provide adequate Note: ventilation and use *Note: The Span Rating in the trademark applies For buildings with wood or steel framed walls, provide 3/4" expansion ground cover vapor when the long panel dimension or strength axis is joints with separate floor framing members and discontinuous wall retarder in crawl across supports unless the strength axis is other- plates over the joints, at intervals that limit continuous floor areas to space. Panels must be 80 feet maximum in length or width, to allow for accumulated expan- dry before applying wise identified. sion during construction in wet weather conditions. finish floor.

27 FLOOR CONSTRUCTION

TABLE 8 APA RATED STURD-I-FLOOR(a) Span Rating Fastening: Glue-Nailed(c) Fastening: Nailed-Only (Maximum Maximum Spacing (in.) Maximum Spacing (in.) Joist Panel Nail Size Nail Size Spacing) Thickness(b) and Supported Intermediate and Supported Intermediate (in.) (in.) Type Panel Edges(g) Supports Type Panel Edges(g) Supports 6d ring- or 6d ring- or 16 19/32, 5/8 screw-shank(d) 12 12 screw-shank 612

6d ring- or 6d ring- or 20 19/32, 5/8 screw-shank(d) 12 12 screw-shank 612

6d ring- or 6d ring- or 23/32, 3/4 screw-shank(d) 12 12 screw-shank 612 24 8d ring- or 8d ring- or 7/8 screw-shank(d) 612screw-shank 612

8d ring- or 8d ring- or 32 7/8 screw-shank(d) 612screw-shank 612

8d ring- or 8d ring- or 48 1-3/32, 1-1/8 screw-shank(e) 6 (f) screw-shank(e) 6 (f)

(a) Special conditions may impose heavy traffic and concentrated loads that (d) 8d common nails may be substituted if ring- or screw-shank nails are require construction in excess of the minimums shown. See page 36 for heavy not available. duty floor recommendations. (e) 10d common nails may be substituted with 1-1/8-inch panels if supports (b) Panels in a given thickness may be manufactured in more than one Span are well seasoned. Rating. Panels with a Span Rating greater than the actual joist spacing may be (f) Space nails maximum 6 inches for 48-inch spans and 12 inches for substituted for panels of the same thickness with a Span Rating matching the 32-inch spans. actual joist spacing. For example, 19/32-inch-thick Sturd-I-Floor 20 oc may be substituted for 19/32-inch-thick Sturd-I-Floor 16 oc over joists 16 inches (g) Fasten panels 3/8 inch from panel edges. on center. (c) Use only adhesives conforming to APA Specification AFG-01 or ASTM D3498, applied in accordance with the manufacturer’s recommendations. If OSB panels with sealed surfaces and edges are to be used, use only solvent-based glues; check with panel manufacturer.

TABLE 9 RECOMMENDED UNIFORM FLOOR LIVE LOADS FOR APA RATED STURD-I-FLOOR AND APA RATED SHEATHING WITH STRENGTH AXIS PERPENDICULAR TO SUPPORTS Allowable Live Loads (psf)(a) Sturd-I-Floor Sheathing Minimum Panel Maximum Span Span Thickness Span Joist Spacing (in.) Rating Rating (in.) (in.) 12 16 20 24 32 40 48 16 oc 24/16, 32/16 7/16(c) 16 185 100 20 oc 40/20 19/32, 5/8 20 270 150 100 24 oc 48/24 23/32, 3/4 24 430 240 160 100 32 oc 60/32(b) 7/8 32 430 295 185 100 48 oc 1-3/32, 1-1/8 48 460 290 160 100 55

(a) 10 psf dead load assumed. Live load deflection limit is l/360. (c) 19/32 in. is minimum thickness of Rated Sturd-I-Floor. (b) Check with supplier for availability. Note: Shaded construction meets Code Plus recommendations. See page 29.

28 The Code Plus Floor While lumber has been the traditional The Code Plus floor, constructed with APA APA THE ENGINEERED THE ENGINEERED product used for rim boards, it is not WOOD ASSOCIATION WOOD ASSOCIATION either APA RATED STURD-I-FLOOR or compatible with the new generation of RATED STURD-I-FLOOR RATED STURD-I-FLOOR APA RATED SHEATHING, provides 1-1/8 INCH 7/8 INCH wood I-joists used in floor construction. 48oc 2-4-1 32oc SIZED FOR SPACING SIZED FOR SPACING extra strength and stability. Code Plus EXPOSURE 1 EXPOSURE 1 With the increasing use of wood I-joists, T&G 000 T&G 000 PS 1-95 UNDERLAYMENT PRP-108 HUD-UM-40 floor requirements are as follows: PRP-108 a demand for compatible engineered 1. Floor Span Rating must be at least wood rim boards has resulted. 24 oc for floor joist spacing up to For a low profile with supports APA Performance Rated Rim Boards can 20 inches o.c., and 32 oc for joists 48 inches on center, beams can be set be manufactured using plywood, ori- spaced 24 inches o.c. in foundation pockets or on posts sup- ented strand board (OSB), glued lami- 2. Frame the floor with APA EWS trade- ported by footings so that panels bear nated timber (glulam), or laminated marked glulam beams, Performance directly on the sill. If 4x lumber girders veneer lumber (LVL). These engineered Rated I-joists, and APA Performance are used, they should be air dried wood rim boards have less shrinkage Rated Rim Board. and/or set higher than the sill to than lumber and match the depth of 3. Install panels with the APA Glued allow for shrinkage. wood I-joists and other engineered Floor System (see page 30). wood framing products. They are In some applications, particularly in 4. Fasten panels with 8d nails or other available in lengths up to 24 feet, hallways and other heavy traffic areas, code-approved fasteners spaced depending on the product used. 12 inches on all supports. Nail size and greater stiffness in the floor may be Most APA Performance Rated Rim spacing may vary depending on span desirable. Modifications to the 48-inch Boards are wood structural panels that and sheathing thickness. framing system, such as addition of are manufactured in accordance with 5. Leave a 1/8-inch space at all straight or diagonal blocking, will the Performance Standard for APA EWS panel end and edge joints to allow increase stiffness considerably. Rim Boards and Voluntary Product for panel expansion. APA Performance Rated Standards PS 1 or PS 2, or APA Standard 6. Install panels continuously over two Rim Board PRP-108. Glulam rim boards are a or more spans with the long dimension A rim board is the wood component resawn grade of glued laminated timber or strength axis across supports. that fills the space between the manufactured in accordance with the and bottom plate of a wall or, in second Sturd-I-Floor 32 oc and 48 oc Performance Standard for APA EWS floor construction, between the top Install APA RATED STURD-I-FLOOR Rim Boards and ANSI A190.1. The plate and bottom plate of two wall 48 oc or 32 oc panels over 2x joists or Performance Standard for APA EWS Rim sections. The rim board must match the I-joists spaced 32 inches on center Boards meets or exceeds the require- depth of the framing members between (Figure 2). Install APA RATED STURD-I- ments given in the ICBO ES Acceptance floors or between the floor and founda- FLOOR 48 oc over 4x girders 48 inches Criteria for Wood-Based Rim Board tion to function properly. In addition to on center (Figure 3). For the 48 oc Products. method, supports may be 2x joists supporting the wall loads, the rim board As glued engineered wood products, spiked together, 4x lumber, glulams, ties the floor joists together. It is an APA Rim Boards have greater dimen- lightweight steel beams, or wood I-joists integral component in an engineered sional stability, higher strength, or floor trusses. Girders of doubled 2x wood system because it transfers both increased structural reliability, more members should have top edges flush to lateral and vertical bearing forces. consistent quality and a lower tendency permit smooth panel end joints. to check or split than sawn lumber.

29 FLOOR CONSTRUCTION

The APA Glued Floor System The APA Glued Floor System is based FIGURE 4 on thoroughly tested gluing techniques APA GLUED FLOOR SYSTEM and field-applied construction adhesives Carpet and pad that firmly and permanently secure a layer of wood structural panels to wood 2x rim joist or APA Rim Board joists. The glue bond is so strong that Strength axis Tongue-and-groove floor and joists behave like integral edges (or 2" lumber T-beam units. Floor stiffness is increased blocking between appreciably over conventional construc- supports) tion, particularly when tongue-and- Stagger end joints groove joints are glued. Gluing also Note: Site-applied glue, both joints helps eliminate squeaks, floor vibration, Provide adequate ventilation and use and tongue-and-groove joints (or bounce and nail-popping. ground cover vapor between panels and edge blocking) retarder in crawl Field-glued floors go down quickly, space. Panels must be 1/8" spacing is recommended at all dry before applying even in cold weather, using ordinary finish floor. edge and end joints unless otherwise indicated by panel manufacturer construction materials and techniques. Note: 2x joists, I-joists or floor And like many other panel assemblies For buildings with wood or steel framed walls, provide 3/4" expansion joints with separate floor trusses –16", 19.2", 24", or 32" o.c. that provide excellent sound control, framing members and discontinuous wall plates over (4x supports for 48" o.c. spacing) the joints, at intervals that limit continuous floor areas the APA Glued Floor System is ideal for to 80 feet maximum in length or width, to allow for APA RATED STURD-I-FLOOR accumulated expansion during construction in wet multifamily construction. The large weather conditions. 16, 20, 24, 32 or 48 oc panels with glued tongue-and-groove joints reduce the number of cracks that can “leak” airborne noise. Panels recommended for glued floor or fully adhered carpet.) Exposure 1 or The system is normally built with construction are tongue-and-groove APA Exterior should be specified for applica- span-rated STURD-I-FLOOR panels RATED STURD-I-FLOOR for single- tions subject to moisture during or after (Figure 4), although double-layer floors floor construction, and APA RATED construction, as in bathrooms and are also applicable. In both cases, SHEATHING for the subfloor when utility rooms. STURD-I-FLOOR and subflooring used with a separate underlayment Tongue-and-groove panels are highly panels should be installed continuous or with structural finish flooring. (An recommended for single-floor construc- over two or more spans with the additional layer of underlayment, or tion. Before each panel is placed, a line long dimension or strength axis veneer-faced STURD-I-FLOOR with of glue is applied to the joists with a across supports. “sanded face” should be applied in caulking gun. The panel T&G joint areas to be finished with resilient floor should also be glued, although less coverings such as tile, linoleum, vinyl heavily to avoid squeeze-out. If square- edge panels are used, edges must be supported between joists with 2x4

30 Application 6. After first row of panels is in place, APA APA For best results, follow these application spread glue in groove of one or two THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION procedures: panels at a time before laying next row. RATED STURD-I-FLOOR RATED STURD-I-FLOOR 24 oc 23/32 INCH 24 oc 23/32 INCH Glue line may be continuous or spaced, SIZED FOR SPACING SIZED FOR SPACING 1. Snap a across joists EXPOSURE 1 T&G NET WIDTH 47-1/2 but avoid squeeze-out by applying a 000 EXPOSURE 1 four feet in from wall for panel edge PRP-108 HUD-UM-40 000 PS 1-95 UNDERLAYMENT thinner line (1/8 inch) than on joists. PRP-108 alignment and as a boundary for spreading glue. 7. Tap second-row panels into place, APA 2. Spread only enough glue to lay one or using a block to protect groove edges. THE ENGINEERED WOOD ASSOCIATION two panels at a time or follow specific 8. Stagger end joints in each succeeding RATED SHEATHING 32/16 15/32 INCH recommendations of glue manufacturer. row. A 1/8 inch space between all SIZED FOR SPACING EXPOSURE 1 Wipe any mud, dirt or water from joists end joints and 1/8 inch at all edges, 000 PRP-108 HUD-UM-40 before gluing. including T&G, is recommended. (Use 3. Lay first panel with tongue side to a spacer to assure accurate and blocking. Glue panels to blocking to wall and nail in place. This protects the consistent spacing.) minimize squeaks. Blocking is not tongue of next panel from damage when 9. Complete all nailing of each panel required under structural finish flooring, tapped into place with block and before glue sets. (See Table 8.) Check such as wood strip flooring, or if a sledgehammer. the manufacturer’s recommendations separate underlayment is installed. 4. Apply a continuous line of glue for allowable time. (Warm weather Only adhesives conforming with (about 1/4-inch diameter) to framing accelerates glue setting.) Use 6d ring- or Performance Specification AFG-01 members. Apply glue in a serpentine screw-shank nails for panels 3/4 inch developed by APA or ASTM D3498 are pattern on wide areas. thick or less, and 8d ring- or screw- shank nails for thicker panels. Space recommended for use with the Glued 5. Apply two lines of glue on joists nails per Table 8. Closer nail spacing Floor System. A number of brands where panel ends butt to assure proper may be required by some codes, or for meeting this specification are available gluing of each end. from building supply dealers. If OSB diaphragm construction. Finished deck panels with sealed surfaces and edges can be walked on and will carry con- are to be used, use only solvent-based struction loads without damage to glues; check with panel manufacturer. glue bond. Always follow the specific application recommendations of the glue manufacturer.

31 FLOOR CONSTRUCTION

APA Panel Subflooring subfloors on spans up to 24 inches and 3. 3/4-inch wood strip flooring is The limiting factor in the design of 11/32 inch or thicker panels on spans installed over the subfloor perpendicular floors is deflection under concentrated longer than 24 inches. to the unsupported edge. loads at panel edges. The Span Ratings 2. A minimum of 1-1/2 inches of If floor has become wet during construc- in Table 10 apply to APA RATED lightweight concrete is applied over tion, it should be allowed to dry before SHEATHING grades only, and are the the panels. application of finish floor, including minimum recommended for the spans indicated. The spans assume panels continuous over two or more spans FIGURE 5 with the long dimension or strength APA PANEL SUBFLOORING axis across supports.* Recommended live loads are given in Wood strip, wood blocks, or Stagger end joints (optional) lightweight concrete flooring Table 9. Spans are limited to the values 1/8" spacing is recommended at all shown because of the possible effect of edge and end joints unless otherwise concentrated loads. indicated by panel manufacturer

Nailing recommendations are given in xis th a Table 10. Other code-approved fasteners Streng may be used. APA panel subflooring may also be glued for added stiffness 2x joists, I-joists and to reduce squeaks using nailing or floor trusses recommendations in Table 8. APA RATED SHEATHING 2x rim joist Long edges should be tongue-and- or APA groove or supported with blocking Rim Board unless: Note: Note: Provide adequate For buildings with wood or steel framed walls,provide 3/4" 1. A separate underlayment layer is ventilation and use ground cover expansion joints with separate floor framing members and vapor retarder in crawl space. discontinuous wall plates over the joints, at intervals that installed with its joints offset from those Subfloor must be dry before limit continuous floor areas to 80 feet maximum in length applying subsequent layers. or width, to allow for accumulated expansion during in the subfloor. The minimum thickness construction in wet weather conditions. of underlayment should be 1/4 inch for

TABLE 10 APA PANEL SUBFLOORING (APA RATED SHEATHING)(a)(b) Maximum Nail Spacing (in.) Panel Panel Span Thickness Maximum Span Nail Size Supported Intermediate Rating (in.) (in.) & Type(e) Panel Edges(g) Supports 24/16 7/16 16 6d common 6 12 32/16 15/32, 1/2 16 8d common(c) 612 40/20 19/32, 5/8 20(d) 8d common 6 12 48/24 23/32, 3/4 24 8d common 6 12 60/32(f) 7/8 32 8d common 6 12

(a) For subfloor recommendations under ceramic tile, refer to Table 12. For (d) Span may be 24 inches if a minimum 1-1/2 inches of lightweight concrete subfloor recommendations under gypsum concrete, contact manufacturer of is applied over panels. floor topping. (e) Other code-approved fasteners may be used. (b) APA RATED STURD-I-FLOOR may be substituted when the Span Rating is (f) Check with supplier for availability. equal to or greater than tabulated maximum span. (g) Fasteners shall be located 3/8 inch from panel edges. (c) 6d common nail permitted if panel is 1/2 inch or thinner.

32 underlayment, hardwood flooring, Lightweight Concrete Over APA Panels APA APA ceramic tile, etc. After it is dry, the THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION floor should be checked for flatness, APA RATED SHEATHING or STURD- UNDERLAYMENT UNDERLAYMENT especially at joints. I-FLOOR panels are an excellent base 19/32 INCH A-C GROUP 1 GROUP 1 for lightweight concrete floors. See PLUGGED CROSSBANDS UNDER FACE APA RATED SHEATHING Exposure 1 EXTERIOR EXPOSURE 1 “APA Rated Sturd-I-Floor,” page 26, or 000 000 may be used where temporary exposure PS 1-95 PS 1-95 “APA Panel Subflooring,” page 32, for to moisture or the weather is expected application recommendations. For during construction. However, only APA gypsum concrete recommendations, THE ENGINEERED Exterior panels should be used where WOOD ASSOCIATION contact manufacturer of floor topping. C-C PLUGGED long-term exposure to moisture or the 11/32 INCH Install panels continuous over two or GROUP 1 weather will be required. SANDED FACE more spans with the strength axis EXTERIOR 000 In some nonresidential buildings, across supports. Use a moisture barrier PS 1-95 greater traffic and heavier concentrated when recommended by concrete manu- loads may require construction in excess facturer. (See “Noise Transmission tures from concentrated loads. Applied of the minimums given. Where joists are Control,” page 65, and Figure 35 for an as recommended, plywood underlay- 16 inches on center, for example, panels illustration of a typical assembly.) ment is also dimensionally stable and with a Span Rating of 40/20 or 48/24 eliminates excessive swelling and subse- will give additional stiffness. For beams APA Plywood Underlayment quent buckling or humps around nails. or joists 24 or 32 inches on center, Underlayment grades of plywood have 1-1/8-inch panels provide additional a solid, touch-sanded surface for direct Always protect plywood underlayment stiffness. application of carpet and pad. For areas against physical damage or water prior to be covered with resilient floor cover- to application. Panels should, however, *Note: The Span Rating in the trademark applies ing, specify panels with “sanded face,” be allowed to equalize to atmospheric when the long panel dimension or strength axis is across supports unless the strength axis is other- or certain other grades as noted in Table conditions by standing individual wise identified. 11. Special inner-ply construction of panels on edge for several days Underlayment resists dents and punc- before installation.

TABLE 11 APA PLYWOOD UNDERLAYMENT(c) Minimum Maximum Fastener Plywood Spacing (in.)(e) Thickness Panel Plywood Grades(a) Application (in.) Fastener Size and Type Edges(d) Intermediate APA UNDERLAYMENT 3d x 1-1/4-in. Over smooth subfloor 1/4 3 6 each way APA C-C Plugged EXT APA ring-shank nails(b) RATED STURD-I-FLOOR Over lumber subfloor min. 12-1/2 gage 11/32 6 8 each way (19/32" or thicker) or uneven surfaces (0.099 in.) shank dia.

(a) In areas to be finished with resilient floor coverings such as tile or sheet (b) Use 4d x 1-1/2-in. ring-shank nails, minimum 12-1/2 gage (0.099 in.) vinyl, or with fully adhered carpet, specify Underlayment, C-C Plugged or shank diameter, for underlayment panels 19/32 inch to 3/4 inch thick. veneer-faced STURD-I-FLOOR with “sanded face.” Underlayment A-C, (c) For underlayment recommendations under ceramic tile, refer to Table 12. Underlayment B-C, Marine EXT or sanded plywood grades marked “Plugged Crossbands Under Face,” “Plugged Crossbands (or Core),” “Plugged Inner (d) Fasten panels 3/8 inch from panel edges. Plies” or “Meets Underlayment Requirements” may also be used under (e) Fasteners for 5-ply plywood underlayment panels and for panels greater resilient floor coverings. than 1/2 inch thick may be spaced 6 inches on center at edges and 12 inches each way intermediate.

33 FLOOR CONSTRUCTION

Install plywood underlayment, smooth side up, immediately before laying the FIGURE 6 finish floor. For maximum stiffness, APA PLYWOOD UNDERLAYMENT place face grain across supports. End Tile, sheet goods, carpet End joint stagger optional and edge joints of underlayment panels or nonstructural flooring for subfloor panels should be offset by at least two inches from joints of subfloor panels, and Stagger end joints in should not coincide with framing below. underlayment panels (optional under Begin fastening at one edge next to a carpet and pad) preceding panel. Assuring that the panel is uniformly flat, continue by fully fas- tening toward opposite edge. Make sure fasteners are flush with or just slightly APA plywood below surface of Underlayment just underlayment (see APA RATED SHEATHING Table 11 for under- or board subflooring (sub- prior to installation of resilient floor layment recommen- flooring must be dry before coverings such as tile, or sheet vinyl (see dations for thin laying underlayment) flooring products) Table 11 for underlayment No blocking required if underlayment recommendations for thin flooring Provide 1/32" space between joints are offset from subfloor joints products). Fill and thoroughly sand underlayment joints edge joints (this step may not be neces- sary under some carpet and structural flooring products – check recommenda- Hardwood Flooring Over subfloor. Do not install hardwood tions of flooring manufacturer). Fill any APA Panel Subfloors unless subfloor moisture level is within other damaged or open areas, such as APA panel subfloor spans for 3/4-inch a range consistent with the hardwood splits, and sand all surface roughness. hardwood strip flooring are limited to manufacturer’s recommendations. If the maximum spacing of floor framing listed home is built over a crawl space, make The plywood underlayment needed to in Tables 9 and 10. For improved sure the crawl space is dry and well- bridge an uneven floor will depend on stiffness, and to help eliminate floor drained. A 6-mil polyethylene vapor roughness and loads applied. Although squeaks when hardwood flooring is retarder should be installed on the a minimum 11/32-inch thickness is installed, construction in accordance ground in the crawl space. recommended, 1/4-inch plywood with Code Plus Floors is recommended underlayment may also be acceptable Follow the recommendations of the (see page 28) by both the National over smooth subfloors, especially in National Oak Flooring Manufacturers Flooring Manufacturers Association remodeling work. (See Table 11.) Association (NOFMA) or National (NOFMA) and the National Wood Floor Wood Floor Association (NWFA) for the Where floors may be subject to tempo- Association (NWFA)*. Both NOFMA hardwood flooring product being used rary moisture, use panels with exterior and NWFA also recommend the use of and its storage and handling, and for glue (Exposure 1) or APA C-C minimum 23/32" OSB and plywood as acclimatizing the hardwood prior to PLUGGED Exterior. APA C-D a subfloor material. installation on the subflooring. PLUGGED is not an adequate substitute Because hardwood flooring is sensitive for Underlayment grade since it does not to moisture, make sure subflooring *National Oak Flooring Manufacturers ensure equivalent dent resistance. Association, P.O. Box 3009, Memphis, Tennessee, panels are dry before hardwood is 38173-0009; Phone (901) 526-5016. installed. Use a moisture meter to National Wood Floor Association, 16388 measure the moisture content of the Westwoods Business Park, Ellisville, Missouri 63021; Phone (800) 422-4556.

34 Ceramic Tile Over APA Plywood Floors TABLE 12 Recommendations for several plywood APA PLYWOOD SYSTEMS FOR CERAMIC TILE FLOORING (Based on floor systems suitable for application of ANSI Standard A108 and specifications of the Tile Council of America) ceramic tile are given in Table 12, based Joist Minimum Panel Thickness (in.) Spacing on specifications of the Tile Council of (in.) Subfloor(a)(g) Underlayment(b)(g) Tile Installation America (TCA)*. Note that maximum Residential joist spacing for all systems is 16 inches, 16 19/32 (c) (d) “Dry-Set” mortar, cement paste or latex – portland and that the plywood floor construction cement mortar used depends on the tile installation 16 23/32 – Cement mortar (1-1/4")(f) system selected. 16 19/32 19/32 Organic adhesive

*Tile Council of America, Inc., 100 Clemson 16 19/32 15/32(e) Epoxy mortar and grout Research Blvd., Anderson, South Carolina 29625, Phone (864) 646-8453 Light Commercial 16 19/32 (c) (d) “Dry-Set” mortar, cement paste or latex – portland cement mortar 16 23/32 – Cement mortar (1-1/4")(f) 16 19/32 19/32(e) Epoxy mortar and grout

(a) APA RATED SHEATHING with Span Rating of (e) Leave 1/4" space at panel ends and edges; 40/20 (19/32" panel) or 48/24 (23/32" panel). trim panels as necessary to maintain end spac- (b) APA Underlayment or sanded Exterior grade, ing and panel support on framing. Fill joints with except as noted. epoxy mortar when it is spread for setting tile. (c) Attach Cementitious Backer Units (CBU) over (f) Use No. 15 asphalt felt or 4-mil polyethylene a supporting of “Dry-Set” or latex-portland sheeting over subfloor. Reinforce mortar with cement mortar with galvanized nails, screw-type wire mesh. nails or other corrosion-resistant fasteners. 7/16" (g) See Table 8, 10 or 11, as applicable, for minimum thickness CBU required for light panel fastening recommendations. commercial service. (d) Leave 1/8" space at panel ends and edges. Fill joints with “Dry-Set” or latex-portland cement mortar.

35 FLOOR CONSTRUCTION

APA Panel Stair Treads and Risers FIGURE 7 A growing number of builders and APA PANEL STAIR TREADS AND RISERS manufacturers are using APA panels for 8d common nails 6" o.c.* APA panel tread treads and risers of both site-fabricated Detail A (May be used for (strength axis either plywood treads and 1-1/8" *Predrill tread end grain at and prefabricated stairs in closed-riser composite panel or OSB mid-thickness with 3/32" bit. direction) stairways. Risers support the front and treads) Maintain at least 3/8" edge Riser distance in riser. back of the tread, creating a very short, Tread effective span. 3/8" Finish flooring min. material

APA panel stair treads may be used Strength axis interchangeably with boards when the system is to include closed risers. Detail B (Preferred) Maximum span between stringers is 42 inches (check local code require- Riser ments). Rounded nosing may be machined into the tread, but should be Stringer covered by a finish flooring material Tread Lumber block such as carpet and pad in order to prevent excessive wear or damage to 8d common nails 19/32" minimum APA 12" o.c. panel riser (any grade) veneers exposed by rounding. Risers may be any available APA panel grade at least 19/32 inch thick. Panel grade and thickness recommendations for the Tables 14 and 15 give plywood recom- TABLE 13 treads are given in Table 13. Glue is mendations for uniform and concen- recommended to improve stiffness of APA PANEL STAIR TREADS trated (e.g., forklift traffic) loads. These Minimum assume the use of plywood continu- connections and to eliminate squeaks. Thickness (in.) Apply construction adhesive meeting Panel Nail- Nailed- ous over two or more spans with face APA Performance Specification AFG-01 Grade(a) Glued Only grain across supports. Structural edge or ASTM D3498 to all joints, with par- APA RATED support must be provided where high STURD-I-FLOOR 19/32 23/32 ticular attention to the connection at concentrated loads occur. Where no the back riser. Regardless of where glue (a) Other appropriate APA panel grades lift-truck use is expected, two-inch may be substituted for Sturd-I-Floor, is used, nail all edges of treads as indi- providing minimum thickness complies wood framing is adequate. with recommendations above. cated in Figure 7. Detail A is the In addition to providing structural simplest system, but Detail B is preferred strength, a wearing surface should be since it eliminates end-grain nailing at Heavy Duty Plywood Floors provided to resist crushing wood cells the back riser and may be used for all Above-grade plywood floors may be and avoid abrasion whenever an indus- recommended panels. designed to support forklift trucks in trial floor is subject to hard wheel or areas of heavy loading or to support caster traffic. An expendable layer of ply- relatively high loads imposed by ware- wood or a dense wear surface such as house shelving or stacked storage. tempered hardboard should be used if Heavy-duty plywood floors also make wheels are small, hard or heavily loaded. excellent mezzanine decks and vibra- tion-resistant surfaces for mounting computer equipment.

36 TABLE 14 PS 1 PLYWOOD RECOMMENDATIONS FOR UNIFORMLY LOADED HEAVY DUTY FLOORS(a) (Deflection limited to 1/240 of span.) (Span Ratings apply to APA RATED SHEATHING and APA RATED STURD-I-FLOOR, respectively, marked PS 1.) Uniform Center-to-Center Support Spacing (inches) (Nominal 2-Inch-Wide Supports Unless Noted) Live Load (psf) 12(b) 16(b) 20(b) 24(b) 32 48(c) 50 32/16, 16 oc 32/16, 16 oc 40/20, 20 oc 48/24, 24 oc 48 oc 48 oc 100 32/16, 16 oc 32/16, 16 oc 40/20, 20 oc 48/24, 24 oc 48 oc 1-1/2(d) 125 32/16, 16 oc 32/16, 16 oc 40/20, 20 oc 48/24, 24 oc 48 oc 1-3/4(d), 2(d) 150 32/16, 16 oc 32/16, 16 oc 40/20, 20 oc 48/24, 48 oc 48 oc 1-3/4(e), 2(d) 200 32/16, 16 oc 40/20, 20 oc 48/24, 24 oc 48 oc 1-1/8(e), 1-3/8(d) 2(e), 2-1/2(d) 250 32/16, 16 oc 40/20, 24 oc 48/24, 48 oc 48 oc 1-3/8(e), 1-1/2(d) 2-1/4(e) 300 32/16, 16 oc 48/24, 24 oc 48 oc 48 oc 1-1/2(e), 1-5/8(d) 2-1/4(e) 350 40/20, 20 oc 48/24, 48 oc 48 oc 1-1/8(e), 1-3/8(d) 1-1/2(e), 2(d) 400 40/20, 20 oc 48 oc 48 oc 1-1/4(e), 1-3/8(d) 1-5/8(e), 2(d) 450 40/20, 24 oc 48 oc 48 oc 1-3/8(e), 1-1/2(d) 2(e), 2-1/4(d) 500 48/24, 24 oc 48 oc 48 oc 1-1/2(d) 2(e), 2-1/4(d)

(a) Use plywood with T&G edges, or provide structural (c) Nominal 4-inch-wide supports. blocking at panel edges, or install a separate underlayment. (d) Group 1 face and back, any species inner plies, sanded or (b) A-C Group 1 sanded plywood panels may be substituted for span- unsanded, single layer. rated Sturd-I-Floor panels (1/2-inch for 16 oc; 5/8-inch for 20 oc; (e) All-Group 1 or Structural I plywood, sanded or unsanded, single layer. 3/4-inch for 24 oc).

TABLE 15 PS 1 PLYWOOD RECOMMENDATIONS FOR FLOORS CARRYING FORK-TRUCK TRAFFIC(a)(b)(c) (Plywood grade is all-Group 1 or Structural I A-C or C-C Plugged, except where 2-4-1 [STURD-I-FLOOR 48 oc marked PS 1] is noted). Tire Tread Load per Center-to-Center Support Spacing (in.) (Minimum 3-Inch-Wide Supports) Print Width Wheel (in.) (lbs.) 12 16 20 24 500 2-4-1 2-4-1 2-4-1 2-4-1 3 1000 1-1/4" 1-1/4" 1-1/4" 1-1/4" 1500 1-1/2" 1-3/4" 1-3/4" 1-3/4" 2000 2" 2" 2-1/4" 2-1/4" 1000 2-4-1 2-4-1 1-1/8" 1-1/8" 1500 1-1/8" 1-1/8" 1-1/4" 1-1/4" 5 2000 1-1/4" 1-1/2" 1-1/2" 1-3/4" 2500 1-1/2" 2" 2" 2" 3000 1-3/4" 2" 2-1/4" 2-1/4" 2000 1-1/8" 1-1/8" 1-1/4" 1-1/4" 3000 1-1/4" 1-1/2" 1-1/2" 1-3/4" 7 4000 1-3/4" 1-3/4" 1-3/4" 2" 5000 2" 2" 2-1/4" 2-1/2" 6000 2-1/4" 2-1/2" 2-3/4" 3" 3000 1-1/4" 1-1/4" 1-1/4" 1-1/4" 4000 1-1/2" 1-1/2" 1-3/4" 1-3/4" 9 5000 1-3/4" 1-3/4" 2" 2" 6000 2" 2" 2-1/4" 2-1/4" 7000 2-1/4" 2-1/4" 2-3/4" 2-3/4"

(a) Structural blocking (3x4 or 2x6 min.) required at all panel edges. Support or small, hard wheels. A wearing surface should also be considered for areas blocking with framing anchors of adequate capacity or similar devices. where fork-truck traffic is stopping, starting or turning in a tight radius. (b) Provide a wearing surface such as Plyron, polyethylene or a separate layer (c) Use ring- or screw-shank nails with length sufficient to penetrate framing of plywood, hardboard or other hard surface when loads are due to casters, 1-1/2" or panel thickness, whichever is greater. Space nails maximum 4" o.c. at panel edges and 8" o.c. at intermediate supports.

37 WALL CONSTRUCTION

APA Sturd-I-Wall® Sidings are occasionally treated with The APA Sturd-I-Wall system consists water repellents or wood preservatives of APA RATED SIDING (panel or lap) to improve finishing characteristics or applied direct to studs or over nonstruc- durability for certain applications. If the tural , gypsum or rigid foam siding has been treated, be sure the insulation sheathing. Nonstructural surface treatment is dry to avoid solvent sheathing is defined as sheathing not or chemical reaction with the foam recognized by building codes as meeting sheathing. both bending and racking strength Because of the high resistance of foam requirements. sheathing to vapor transmission, a poly- A single layer of panel siding, since it is ethylene vapor retarder or foil-backed strong and rack resistant, eliminates the gypsum wallboard should be installed cost of installing separate structural on the warm side of the wall to avoid sheathing or diagonal wall bracing. Panel condensation problems in the wall sidings are normally installed vertically, cavity. Ordinary foil- or paper-faced but may also be placed horizontally insulation batts are not recommended (long dimension across supports) if as an alternate. horizontal joints are blocked. Maximum When rigid foam insulation sheathing stud spacings for both applications are is used, building codes also generally given in Table 16. require installation of 1/2-inch gypsum When installing panel or lap siding over wallboard, or other materials of the rigid foam insulation sheathing, drive required thermal barrier rating, on the nails flush with the siding surface, the inside surface of the wall for but avoid over-driving, which can result fire protection. in dimpling of the siding due to the See Figures 8 through 12 for panel and compressible nature of foam sheathing. lap siding installation recommendations for the Sturd-I-Wall system or for siding installed over nailable sheathing. APA APA THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION All panel siding edges in Sturd-I-Wall RATED SIDING RATED SIDING construction should be backed with 303 LAP 30-S/W 303-18-S/W 15/32 INCH 19/32 INCH 16 oc GROUP 1 16 oc GROUP 1 SIZED FOR SPACING framing or blocking. Use nonstaining, EXTERIOR EXTERIOR 000 T1-11 000 noncorrosive nails as described in PS 1-95 PRP-108 PS 1-95 PRP-108 HUD-UM-40 FHA-UM-40 Tables 16 and 17 to prevent staining the siding. APA APA Where siding is to be applied at THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION an angle, install only over nailable RATED SIDING RATED SIDING sheathing. LAP 19/32 INCH 7/16 INCH 24 oc 16 oc SIZED FOR SPACING EXTERIOR EXTERIOR 000 000 NOTE: Gluing of siding to framing is not PRP-108 HUD-UM-40 PRP-108 HUD-UM-40 recommended.

38 TABLE 16 APA STURD-I-WALL CONSTRUCTION (Recommendations apply to APA Rated Siding direct to studs and over nonstructural sheathing.) Max. Stud Spacing Max. Nail Spacing(e) Nominal (in.) Nail Size (in.) Thickness Strength Strength (Use nonstaining Siding (in.) Axis Axis box, siding or Panel Intermediate Description(a) or Span Rating Vertical Horizontal casing nails)(b)(c) Edges(i) Supports 11/32 & 3/8 16 24 APA MDO EXT 15/32 & thicker 24 24 Panel 6d for siding 1/2" 6(d) 12(f) Siding thick or less; 8d 16 oc (including T1-11) 16 16(g) APA RATED for thicker siding SIDING EXT 24 oc 24(h) 24(h)

16 along — Lap APA RATED 16 oc — 16 6d for siding 1/2" bottom edge Siding SIDING – LAP EXT thick or less; 8d 24 oc — 24 for thicker siding 24 along — bottom edge (a) For veneered APA RATED SIDING, including APA 303 Siding, Note: Galvanized fasteners may react under wet conditions with the natural recommendations apply to all species groups. extractives of some wood species and may cause staining if left unfinished. (b) If panel siding is applied over foam insulation sheathing, use next regular Such staining can be minimized if the siding is finished in accordance with nail size. If lap siding is installed over rigid foam insulation sheathing up to 1 APA recommendations, or if the roof overhang protects the siding from direct inch thick, use 10d (3") nails for 3/8" or 7/16" siding, 12d (3-1/4") nails for exposure to moisture and weathering. 15/32" or 1/2" siding, and 16d (3-1/2") nails for 19/32" or thicker siding. Use (d) For braced wall section with 11/32" or 3/8" panel siding applied horizon- nonstaining box nails for siding installed over foam insulation sheathing. tally over studs 24" o.c., space nails 3" o.c. along panel edges. (c) Hot-dipped or hot-tumbled galvanized steel nails are recommended for (e) Recommendations of siding manufacturer may vary. most siding applications. For best performance, stainless steel nails or alu- (f) Where basic wind speed exceeds 80 mph, nails attaching siding to interme- minum nails should be considered. APA tests also show that electrically or diate studs within 10% of the width of the narrow side from wall corners shall mechanically galvanized steel nails appear satisfactory when plating meets or be spaced 6" o.c. exceeds thickness requirements of ASTM A641 Class 2 coatings, and is further protected by yellow chromate coating. (g) Stud spacing may be 24" o.c. for veneer-faced siding panels. (h) Maximum stud spacing 16" o.c. for a Code Plus wall. (i) Fasteners shall be located 3/8 inch from panel edges.

FIGURE 8 APA STURD-I-WALL (Vertical Panel Installation)

No diagonal wall Building paper recommended bracing required behind siding with panel siding

Caulk around windows and doors APA RATED SIDING (see Figure 17) panels. All edges supported by framing or blocking.

6" minimum clearance, siding to grade

1/8" spacing is recommended at all edge and end joints unless otherwise indicated by panel manufacturer

39 WALL CONSTRUCTION

FIGURE 9 APA STURD-I-WALL (Horizontal Panel Siding Installation)

Building paper or other code- No diagonal wall 1/8" spacing is recommended at all approved weather-resistive or bracing required edges and end joints unless otherwise air infiltration barrier with panel siding indicated by panel manufacturer

2x4 blocking at at 4' or 8' o.c. to conceal horizontal joints butt joints at panel ends. Nails through battens must penetrate studs at least 1". See Table 16 for maximum stud spacing

APA RATED SIDING panels (nailing as required for Treat panel edges with vertical installation) water repellent. Caulk around windows and doors (see Figure 17).

6" minimum clearance, siding to grade

APA Panel and Lap Siding FIGURE 10 Over Nailable Sheathing APA STURD-I-WALL (Horizontal Lap Siding Installation)(a) The recommendations in Table 17 for panel and lap siding apply to siding APA RATED SIDING Building paper or other installed over nailable sheathing. Unless code-approved weather- (lap siding), maximum otherwise indicated in the local building width 12". Minimum resistive or air infiltration headlap 1". barrier required code, nailable sheathing includes:

Leave1/8" spacing 1. Nominal 1-inch boards with studs and caulk vertical 16 or 24 inches o.c. joints unless otherwise recommended by 2. APA RATED SHEATHING panels siding manufacturer with roof Span Rating of 24 inches or 1-1/2"-wide starter greater installed with strength axis either strip, thickness to match lap siding parallel or perpendicular to studs 16 or 6" minimum clearance, 24 inches o.c. (except 3-ply plywood (a) Diagonal bracing methods permitted by model siding to grade building codes for braced wall segments must be panels must be applied with strength provided. For engineered shear wall segments, use APA Rated Sheathing for wall sheathing under lap siding axis across studs when studs are spaced (see Figure 12). 24 inches o.c.).(a) 3. APA RATED SHEATHING panels with roof Span Rating less than 24 inches installed with strength axis either parallel or perpendicular to studs

40 TABLE 17 APA RATED SIDING OVER NAILABLE SHEATHING (For siding over types of nonstructural sheathing, see Sturd-I-Wall recommendations.) Max. Spacing of Vertical Rows of Nails Max. Nail Spacing(c) (in.) (in.) Nominal Nail Size Thickness Strength Strength (Use nonstaining Siding (in.) Axis Axis box, siding or Panel Intermediate Description(a) or Span Rating Vertical Horizontal casing nails)(b)(c) Edges(d) Supports 11/32 & 3/8 16 24 APA MDO EXT 15/32 & thicker 24 246d for siding 1/2" 6 12 Panel thick or less; 8d Siding APA RATED 16 oc (including T1-11) 16 24 for thicker siding SIDING EXT 24 oc 24 24

APA MDO EXT 11/32 & thicker ——6d for siding 1/2" 8 along — Lap thick or less; 8d bottom edge Siding APA RATED 11/32 & thicker, for thicker siding SIDING – LAP EXT or 16 oc or 24 oc ——

(a) For veneered APA RATED SIDING, including APA 303 Siding, Note: Galvanized fasteners may react under wet conditions with the natural recommendations apply to all species groups. extractives of some wood species and may cause staining if left unfinished. (b) Hot-dipped or hot-tumbled galvanized steel nails are recommended for Such staining can be minimized if the siding is finished in accordance with most siding applications. For best performance, stainless steel nails or alu- APA recommendations, or if the roof overhang protects the siding from direct minum nails should be considered. APA tests also show that electrically or exposure to moisture and weathering. mechanically galvanized steel nails appear satisfactory when plating meets or (c) Recommendations of siding manufacturer may vary. exceeds thickness requirements of ASTM A641 Class 2 coatings, and is further (d) Fasten panels 3/8 inch from panel edges. protected by yellow chromate coating. Note: Shaded nail spacing meets Code Plus wall recommendations.

FIGURE 11 FIGURE 12 APA RATED SIDING APA RATED SIDING (LAP SIDING) OVER NAILABLE SHEATHING (PANEL SIDING) OVER NAILABLE SHEATHING Siding joints, if staggered No diagonal wall bracing required may occur away from studs with APA RATED SHEATHING 1/8" spacing is recommended at with nailable sheathing. all edge and end joints unless Building paper or other code- otherwise indicated by panel approved weather-resistive or manufacturer air infiltration barrier No diagonal wall APA RATED SIDING bracing required (lap siding), maximum Leave 1/8" spacing and with panel siding width 12". Minimum caulk vertical joints, unless headlap 1". otherwise recommended by siding manufacturer 1-1/2"-wide starter strip, thickness to match lap siding 6" minimum clearance, siding to grade

APA RATED SIDING panels applied over sheathing

Building paper or other code-approved weather-resistive or 6" minimum air infiltration barrier clearance, siding to grade

41 WALL CONSTRUCTION

16 inches o.c. (except plywood panels 3/8 inch thick or less must be applied TABLE 18 with strength axis across studs).(a) APA PANEL WALL SHEATHING(a) (APA RATED SHEATHING panels continuous over two or more spans.) Lap siding joints, if staggered, and panel Maximum Nail siding joints may occur away from studs Spacing (in.) with nailable sheathing. Panel Maximum Supported Span Stud Spacing Nail Panel Intermediate Rating (in.) Size(b)(c) Edges(d) Supports (a) Check local building codes for blocking requirements between studs for braced or engi- 12/0, 16/0, neered shear wall segments, when wall sheathing 20/0 16 6d for is installed horizontally across studs. or Wall-16 oc panels NOTE: In addition to panel edge spacing and the 1/2" thick 612 or less; 8d use of straight studs, nailing sequence can also be 24/0, 24/16, a factor in maintaining a uniformly flat appearance for thicker 32/16 24 of the finished wall. Here’s a way to install panel panels siding without built-in compression stress. First, or Wall-24 oc position the panel, maintaining recommended edge spacing, and lightly tack at each corner. (a) See requirements for nailable panel sheath- (c) Other code-approved fasteners may be used. Install the first row of nails at the edge next to ing when exterior covering is to be nailed to (d) Fasteners shall be located 3/8 inch from the preceding panel from top to bottom. Remove sheathing. panel edges. remaining tacking nails. Then nail the row at the (b) Common, smooth, annular, spiral-thread, or Note: Shaded construction meets Code Plus first intermediate stud. Continue by nailing at the galvanized box. recommendations. second intermediate stud, and finally, at the edge opposite the preceding panel. Complete the installation by fastening to the top and bottom plates.

FIGURE 13 APA Panel Wall Sheathing APA PANEL WALL SHEATHING APA RATED SHEATHING easily meets building code wall sheathing require- 1/8" spacing is recom- ments for bending and racking strength mended at all edge and without let-in corner bracing. Even end joints unless other- when fiberboard or other nonstructural wise indicated by panel manufacturer sheathing is used, APA RATED SHEATHING corner panels (Figure 14) “Block” horizontal joints in panels used of the same thickness can eliminate for bracing (check local 6" minimum costly let-in bracing. Installation recom- code for requirements) clearance, siding mendations are given in Figure 13. Filler strip if required to grade Recommended wall sheathing spans APA RATED SHEATHING with brick veneer or masonry are the applied with strength axis same as those for panel sheathing (see parallel to studs

Table 18). See Figure 15 for installation APA RATED SHEATHING applied recommendations. with strength axis across studs Building paper or other code-approved weather-resistive Panel recommendations for preframed Siding or air infiltration barrier wall sections are the same as for built- in-place walls.

NOTE: Gluing of wall sheathing to framing is not APA APA APA THE ENGINEERED THE ENGINEERED THE ENGINEERED recommended, except when recommended by the WOOD ASSOCIATION WOOD ASSOCIATION adhesive manufacturer for wall sheathing that WOOD ASSOCIATION already has been permanently protected by siding. RATED SHEATHING RATED SHEATHING RATED SHEATHING 24/0 3/8 INCH 32/16 15/32 INCH 24/16 7/16 INCH SIZED FOR SPACING SIZED FOR SPACING SIZED FOR SPACING EXPOSURE 1 EXPOSURE 1 EXPOSURE 1 000 000 000 PS 2-92 SHEATHING PS 1-95 C-D PRP-108 PRP-108 HUD-UM-40 PRP-108 HUD-UM-40

42 The Code Plus Wall The Code Plus wall provides superior FIGURE 14 wall racking strength, protecting the APA PANEL CORNER BRACING home from severe winds and earth- quakes. Requirements are as follows: 1. For double wall construction, sheath walls with APA RATED SHEATHING. Supports 16" or 24" o.c. 2. For single wall construction, apply APA RATED SIDING panels which are at least 19/32 inch thick or possess a 1/2" gypsum or fiberboard Span Rating of 24 oc direct to studs spaced 16 inches o.c., or 15/32" or 1/2" APA RATED 3. Apply APA RATED SIDING SHEATHING nailed to studs with panels which are at least 19/32 inch 6d common nails spaced 6" o.c. thick with no grooves or with shallow along panel edges and 12" o.c. at intermediate supports* grooves which are no deeper than the face veneer direct to studs spaced 24 inches o.c. *When corner panels are plywood, 1-1/2" roofing nails spaced 4" o.c. along panel edges and 8" o.c. at intermediate supports 4. Fasten wall sheathing with 6d nails, may be used. or 8d nails for panels greater than 1/2 inch thick, and fasten APA RATED SIDING with 6d or 8d galvanized nails. Space nails 6 inches at supported edges FIGURE 15 and 12 inches at intermediate supports. BRICK VENEER OVER APA PANEL SHEATHING 5. Leave a 1/8-inch space at all edge and end joints to allow for panel expansion. Building paper or other code-approved weather-resistive or air infiltration barrier APA RATED SHEATHING

1" air space

Brick veneer or masonry

“Weep holes” in bottom course every 24"

Hold panel edge 1/2" above base flashing

Extend flashing up behind sheathing at least 6"

43 WALL CONSTRUCTION

APA Sheathing Under Stucco Greater stiffness is recommended for TABLE 19 wall sheathing when stucco is to be RECOMMENDED THICKNESS AND SPAN RATING applied. To increase stiffness, apply the FOR APA PANEL WALL SHEATHING FOR STUCCO EXTERIOR FINISH APA Rated Sheathing(c) long panel dimension or strength axis Stud Minimum Minimum across studs. Blocking or a plywood Spacing Panel Thickness Span Rating (a) cleat is recommended at horizontal (in.) Orientation (in.) joints. Blocking is required for braced Horizontal(b) 3/8 24/0 16 wall sections or shear wall applications. Vertical 15/32(d), 1/2(d) 32/16 For panel recommendations applied

horizontally or vertically, see Table 19. Horizontal(b) 7/16 24/16 24 Siding Joint Details Vertical 19/32(d), 5/8(d) 40/20 The siding joint details in Figure 17 are (a) Strength axis (typically the long panel dimen- (c) Recommendations apply to all-veneer based on the use of APA trademarked sion) perpendicular to studs for horizontal appli- plywood, oriented strand board (OSB) or siding. Nailing of wood structural panel cation; or parallel to studs for vertical application. composite (APA COM-PLY) panels except (b) Blocking recommended between studs along as noted. siding along both edges of shiplap horizontal panel joints. (d) OSB or 5-ply/5-layer plywood. joints (“double nailing”), as shown, is required for shearwalls or those wall segments that must meet bracing requirements. Double nailing is recom- FIGURE 16 mended for all other applications as well STUCCO OVER APA PANEL SHEATHING to provide maximum wall strength and

moisture protection. Building paper is required* Self-furring Where caulks or joint sealants are indi- metal cated, consider the various types avail- able such as urethane, plasticized acrylic Stucco latex, butyl and polysulfide. Check with the manufacturer of the caulk or sealant to determine suitability for the intended application and compatibility with coat- Metal ings and other building materials such as vinyl and aluminum. Building paper In some cases a foam rod or other type filler material may be used behind the APA RATED SHEATHING sealants as recommended by the manu- *Check local building and applicator for specific requirements. facturer. For best results in other cases, Note: apply caulking to framing at panel edges Uniform Building Code requires two layers of grade D paper for stucco over wood-based sheathing. before installing the siding panel; or apply a bead of caulk along the panel edge before installing the next panel. A 1/8-inch space is recommended at all edge and end joints unless otherwise indicated by panel manufacturer. If caulk is to be used, also check with caulk manufacturer for recommended

44 FIGURE 17 PANEL SIDING JOINT DETAILS

VERTICAL WALL JOINTS Butt Shiplap Vertical Reverse Board and Batten Siding Batten

T1-11 & Channel Groove Building paper Apply building paper Use ring-shank nails and treat panel edges Note: for the battens, applied with water repellent Nailing of both panel edges along shiplap near the edges in two joint is recommended. The “double nailing” staggered rows Building is required when wall segment must meet wall paper bracing or engineered shear wall requirements.

VERTICAL INSIDE & OUTSIDE CORNER JOINTS Butt & Caulk Corner Board Lap Joints Lap siding (typ.) Lap Siding (APA Sturd-I-Wall) Caulk Caulk Lap siding Siding Siding (typ.)

Caulk Building paper

Blocking Corner boards Building paper (typ.) Caulk HORIZONTAL WALL JOINTS Butt & Flash Lap Shiplap Siding Siding Siding

Blocking Blocking Blocking Lap top panel Shiplap joint over bottom panel Flashing (galv. or aluminum)

HORIZONTAL BELTLINE JOINTS (For multistory buildings, when conventional lumber floor joists and rim boards are used, make provisions at horizontal joints for shrinkage of framing, especially when applying siding direct to studs.) Jog Exterior Stud Line Band Board Over Panel Filler Band Board In Relief Siding

Floor plate Siding (4' x 8') Band board trim Alum. or galv. flashing Siding Up to 1/2" gap Galv. ‘Z’ flashing when using conven- tional lumber floor Band Joist & rim joists Galv. spikes or bolts () 2x10 band board Wall studs Filler Plastic pipe spacer (2" to 6" dia.) Siding (4' x 8')

WOOD WINDOW DETAILS (For metal window details, contact the American Architectural Manufacturers Association.) Head Jamb Sill Finish wall Siding Int. casing Siding Flashing & caulk Finish sill

Finish wall Caulk Caulk

Int. casing Int. casing Finish wall Glass Glass Siding

45 WALL CONSTRUCTION

edge spacing. Nails through battens or other wood trim must penetrate at TABLE 20 least one inch into studs. Nail panel APA 303 SIDING FACE GRADES(a) siding 6 inches o.c. along edges and 303 Series Type of Patch Plywood Siding 12 inches o.c. at intermediate supports. Grades Wood Synthetic To prevent staining of siding, use hot- 303-OC Not permitted Not permitted dip galvanized, aluminum, or other 303-OL Not applicable for overlays 303-NR Not permitted Not permitted nonstaining nails as described in 303-SR Not permitted Permitted as Tables 16 and 17. natural-defect shape

Siding is often fully exposed to weather 303-6-W Limit 6 Not permitted and thus has increased susceptibility to 303-6-S Not permitted Limit 6 303-6-S/W Limit 6 – any combination elevated moisture conditions. Although siding will periodically experience mois- 303-18-W Limit 18 Not permitted 303-18-S Not permitted Limit 18 ture contents above the threshold value 303-18-S/W Limit 18 – any combination needed to support decay, wood-based siding products have a good history of 303-30-W Limit 30 Not permitted 303-30-S Not permitted Limit 30 performance because they dry down 303-30-S/W Limit 30 – any combination below this threshold value before decay (a) All panels except 303-NR allow restricted minor repairs such as shims. These and such other face can take hold. If trim is installed around appearance characteristics as knots, knotholes, splits, etc., are limited by both size and number in accordance with panel grades, 303-OC being most restrictive and 303-30 being least. Multiple siding, be sure that it doesn’t trap mois- repairs are permitted only on 303-18 and 303-30 panels. Patch size is restricted on all panel grades. ture or reduce the drying ability of the wood. Trim that is applied incorrectly can lead to long-term moisture accumu- sidings are also identified by a face Edge Sealing lation that causes decay. grading system. There are four Moisture enters the end grain of Apply flashing or other means of basic siding classifications within plywood or other wood-based products protection over end grain of siding to the system – Special Series 303, faster than through the surface. minimize water absorption. 303-6, 303-18 and 303-30. Each Consequently, edges and ends of APA class, as shown in Table 20, is RATED SIDING panels or lap siding APA Rated Siding further divided into grades accord- should be sealed. Although edge sealers Patterns and Grades ing to categories of repair and are not necessarily moisture-proof or APA RATED SIDING, including 303 appearance characteristics. permanently durable, they help to plywood siding, is available in a wide minimize sudden changes in moisture variety of surface textures and patterns. Finishing Plywood content in the siding, due to weather. For descriptions of siding surface pat- for Exterior Exposure APA RATED SIDING may be edge terns and thicknesses, refer to APA Care and Preparation sealed at the factory. If the siding is not Product Guide: APA Performance Rated Plywood should be stored and factory-sealed, it can be sealed quickly Sidings, Form E300. Actual dimensions handled with care to avoid damag- at the job site while the panels or lap of groove spacing, width and depth may ing before finishing. Storage in a siding pieces are still in a stack. Edges vary with the manufacturer. Where the cool, dry place out of sunlight or ends cut during construction characteristics of a particular wood and weather is best. If left out- should be resealed. species are desired, specify by grade doors, straps on bundles should be and species preference. loosened or cut and the plywood Siding to be finished with a semitrans- covered. Allow good air circulation parent or solid-color stain can be edge In order to help specifiers select the to prevent moisture condensation sealed with a liberal application of a most appropriate siding appearance for and possible mold growth. paintable, water-repellent sealer. If the any particular job, APA 303 plywood

46 siding is to be painted, use the same paint primer that will be used on the TABLE 21 surface. Horizontal edges, particularly APA 303 SIDING FINISHING RECOMMENDATIONS lower drip edges of siding, should be 303 Series Minimum 1 given special care because of their PlywoodSTAINS primer plus 1 greater wetting exposure. Siding Semitransparent Solid Color topcoat Grades (oil) (oil or latex)(a) (acrylic latex) Finishing 303-OC (b) (b) (b) APA RATED SIDING may be finished 303-OL Not Recommended (d) (b) 303-NR (b) (e) (e) with a variety of products such as 303-SR (c) (e) (e) semitransparent stains, solid-color stains or paint systems. The recommended 303-6-W (b) (b) (b) 303-6-S (c) (b) (b) finishes depend on the type of siding 303-6-S/W (c) (b) (b) product, and whether it has an overlaid surface. 303-18-W (c) (b) (b) 303-18-S (c) (b) (b) Oil-based, semitransparent stains may 303-18-S/W (c) (b) (b) be used on certain veneer-faced siding 303-30-W (c) (b) (b) products as detailed in Table 21. Solid- 303-30-S (c) (b) (b) color stains may be used on most APA 303-30-S/W (c) (b) (b)

RATED SIDING products and usually (a) Except for overlaid panels, use a stain- (d) Some panel manufacturers recommend only resistant primer with light-colored latex stains, acrylic latex formulations. Consult the manufac- provide better protection. In general, since the wood extractives may cause a discol- turer’s recommendations. however, best overall performance on oration of the finish. (e) Only acrylic latex formulations are recom- (b) Recommended with provisions given in text. mended when solid-color stains or paint systems APA RATED SIDING products can (c) Should not be finished with semitransparent are applied over open voids. stain unless specifically recommended by the be achieved with an all-acrylic latex panel manufacturer. paint system. For overlaid siding, any top-quality exterior house paint system formulated Semitransparent Stains (oil-based only) This is often a satisfactory finishing for wood performs satisfactorily. Oil-based semitransparent stains empha- system, therefore, where semitranspar- Solid-color stains may also be used on size grain patterns, texture and natural ent stains are unsuitable. is overlaid sidings, although some manu- characteristics in the wood. They may be also muted with solid-color stains but facturers recommend only acrylic latex used on plywood face grades 303-OC, wood surface textures usually remain formulations. For specific recommenda- 303-NR and 303-6-W. It is the only finish evident. When in question, the finish tions on finishing OSB siding products, recommended for use over brushed should be applied to a representative consult the siding manufacturer. plywood. Other 303 face grades should sample in order to demonstrate the Table 21 provides a summary of finish- not be finished with semitransparent finished appearance. ing recommendations for APA 303 stains unless specifically recommended Solid-color stains are particularly Siding face grades. For complete infor- by the panel manufacturer. recommended for grades 303-6-S and mation, write for APA Product Guide: Solid-Color Stains 303-6-S/W, as well as 303-18 and Performance Rated Sidings, Form E300. (oil or all-acrylic latex) 303-30 with any type of patch. An opaque or solid-color stain obscures color differences in the wood and between repairs and surrounding wood.

47 WALL CONSTRUCTION

Paints (all-acrylic latex) Top-quality acrylic latex house paint FIGURE 18 systems are recommended for all APA PANELING NEW INTERIOR WALLS Rated Sidings, except brushed plywood. Leave 1/32" spacing If house paint is used on plywood at panel edges siding, an all-acrylic latex paint system consisting of at least one stain-blocking prime coat and an all-acrylic latex topcoat is recommended. For extractive staining woods, some house paint sys- tems utilize an oil-alkyd primer. Others use up to two coats of a stain-blocking acrylic latex primer. These latter systems help to reduce face-checking and gener- ally offer superior performance. A paint finish tends to mask the textured plywood surface more than either Note: semitransparent or solid-color stains. If applied horizontally, block all unsupported edges. On the other hand, a top-quality acrylic latex paint system provides the most durable finish. FIGURE 19 Grade 303-OL may be finished with any top-quality exterior paint system – PANELING EXISTING INTERIOR WALLS primer and companion topcoat – Leave 1/32" spacing formulated for wood. at panel edges Field Application of Finish Proper surface preparation is important for good performance of finishes on any Install 1x2 furring strips surface. Remove dirt and loose wood horizontal and/or vertical with nails into studs, expan- fibers with a stiff nonmetallic bristle sion bolts, concrete nails, brush. Mildew may be removed with a powder-actuated fasteners, solution of 1/4 part household bleach to or adhesive as necessary 3/4 part warm water. Be sure to rinse thoroughly after application of bleach. Block all unsupported edges Finishes should be applied as soon as possible after installation of the siding. Weathering of unprotected wood can cause surface damage in as little as two to four weeks. Apply finishes during favorable weather conditions. As a rule of thumb, finishes should not be applied

48 when the outside air temperature is Interior Paneling Panel Backing expected to drop below 50° F (10° C) APA RATED SIDING panels lend them- Wood structural panels are excellent within 24 hours for latex finishes, or selves to a number of decorative surface backing for wall coverings such as rare 40° F (5° C) for oil-based finishes. treatments for attractive interior panel- , vinyl surfaces and decora- However, recommendations of individ- ing and accent walls. (See Figures 18 tive fabrics. Panels less than 15/32 inch ual manufacturers may vary and should and 19.) Such treatments include thick should be applied with strength always be followed. Wood surfaces -textured, brushed, embossed and axis perpendicular to studs and with should be clean and dry, although grooved. Let APA panels acclimatize 2x4 blocking at horizontal edges. extremely dry surfaces should be to room temperature and humidity Thicker plywood may be applied with dampened slightly when applying conditions for several days prior to strength axis parallel to studs. Plywood latex finishes. attachment to the wall. This can be panels should have C-Plugged or better Use only top-quality finishes and accomplished by placing the panels on faces. Use 6d nails spaced 6 inches on application equipment. Finishes should edge with space between each panel to center at panel edges and 12 inches on be applied according to the spread rates allow air to circulate freely over both center at intermediate supports. A recommended by the manufacturer. sides. Preservative treatment of furring 1/16-inch space should be left between Textured surfaces may require up to or studs is recommended when they are panels. Where moisture may be present, twice as much finish as smooth attached to masonry or concrete exterior use nonstaining nails and either surfaces. The first coat should be walls and to any uncured concrete wall. Exposure 1 or Exterior applied by brush. If spray equipment is Also, in these instances, install a 4-mil type panels. A 1/4-inch clearance is used to apply the finish, then the finish polyethylene vapor retarder between the recommended at the bottom edge of should be either back-brushed or back- paneling and the furring or studs and the panels. rolled while it is still wet. Subsequent insulate exterior walls. Support and nail coats of finish may be applied by any spacing recommendations are given in conventional means. Table 22. Recommendations apply to all species groups.

TABLE 22 INTERIOR PANELING Maximum Nail Spacing (in.) Nail Size Panel Maximum Support (Use casing or Intermediate Thickness (in.) Spacing (in.) finishing nails) Panel Edges Supports 1/4 16(a) 4d 6 12 5/16 16(b) 6d 6 12 11/32 - 1/2 24 6d 6 12 19/32 - 3/4 24 8d 6 12 Texture 1-11 24 8d 6 12

(a) Can be 20 inches if strength axis of paneling is across supports. (b) Can be 24 inches if strength axis of paneling is across supports.

49 WALL CONSTRUCTION

FIGURE 20 APA APA THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION SHEAR WALL FOUNDATION ANCHOR RATED SHEATHING RATED SHEATHING 32/16 15/32 INCH STRUCTURAL I 15/32 INCH High shear wall overturning moments may be trans- SIZED FOR SPACING 32/16 EXPOSURE 1 SIZED FOR SPACING ferred by a fabricated steel bracket such as this. 000 EXPOSURE 1 PS 2-92 SHEATHING 000 Regular foundation bolts may be all that is required PRP-108 HUD-UM-40 PS 1-95 C-D PRP-108 in some cases.

APA RATED SHEATHING or APA RATED SIDING 303 APA APA THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION

RATED SIDING RATED SHEATHING Studs 303-18-S/W 3/8 INCH 15/32 INCH 24/0 Bolts to framing, 24 oc GROUP 1 SIZED FOR SPACING SIZED FOR SPACING EXPOSURE 1 size as required EXTERIOR 000 000 STRUCTURAL I RATED PS 1-95 FHA-UM-40 DIAPHRAGMS-SHEAR WALLS PRP-108 PRP-108 HUD-UM-40

Holddown anchor Sill plate APA THE ENGINEERED Flashing to separate WOOD ASSOCIATION siding from concrete RATED SHEATHING 40/20 19/32 INCH Bolt to foundation SIZED FOR SPACING EXPOSURE 1 000 Concrete foundation PRP-108 HUD-UM-40

APA Panel Shear Walls walls with APA RATED SHEATHING, 2. Determine the required panel grade While all of the wall systems presented with plywood APA RATED SIDING and thickness, and nailing schedule here will provide sufficient strength installed directly to studs (APA Sturd-I- from Table 23. Check anchor bolts in under normal conditions in residential Wall), and with panels applied over sill plate for shear. and light-frame construction, shear walls gypsum sheathing for walls required to 3. Check wall framing on each end of may be desirable or required in areas of be fire rated from the outside. shear wall and design foundation the country with frequent seismic activ- To design a shear wall, follow anchor if required (see Figure 20). ity or high wind loads. Shear walls, of these steps. Design data for roof diaphragms are course, are also integral to commercial 1. Determine the unit shear transferred given on pages 59 and 60. For and industrial construction. by the roof diaphragm to the wall. complete information on shear walls Either APA RATED SHEATHING or all- This generally will be one-fourth the and diaphragms, write for APA Design/ veneer plywood APA RATED SIDING area of the adjacent wall, multiplied by Construction Guide: Diaphragms and (and other APA RATED SIDING panels the wind load, divided by the length Shear Walls, Form L350. that qualify on a proprietary basis) can of the shear wall being designed be used in shear wall design. The data (subtract length of large openings). presented here give maximum shears for

50 TABLE 23 RECOMMENDED SHEAR (POUNDS PER FOOT) FOR APA PANEL SHEAR WALLS WITH FRAMING OF DOUGLAS-FIR, LARCH, OR SOUTHERN PINE(a) FOR WIND OR SEISMIC LOADING(b) Panels Applied Over Panels Applied Direct to Framing 1/2" or 5/8" Gypsum Sheathing Minimum Minimum Nominal Nail Nail Size Nail Spacing at Nail Size Nail Spacing at Panel Penetration (common or Panel Edges (in.) (common or Panel Edges (in.) Panel Grade Thickness in Framing galvanized galvanized (in.) (in.) box) 6 4 3 2(e) box)6432(e) 5/16 1-1/4 6d 200 300 390 510 8d 200 300 390 510 (d) (d) (d) (d) APA 3/8 230 360 460 610 STRUCTURAL I 7/16 1-3/8 8d 255(d) 395(d) 505(d) 670(d) 10d 280 430 550(f) 730 grades 15/32 280 430 550 730 15/32 1-1/2 10d 340 510 665(f) 870 ———— 5/16 or 1/4(c) 180 270 350 450 180 270 350 450 1-1/4 6d APA RATED 3/8 200 300 390 510 8d 200 300 390 510 SHEATHING; APA 3/8 220(d) 320(d) 410(d) 530(d) RATED SIDING(g) (d) (d) (d) (d) (f) and other APA 7/16 1-3/8 8d 240 350 450 585 10d 260 380 490 640 grades except 15/32 260 380 490 640 species Group 5 15/32 310 460 600(f) 770 — ———— 1-1/2 10d 19/32 340 510 665(f) 870 — ————

APA RATED Nail Size Nail Size SIDING(g) and (galvanized (galvanized casing) casing) other APA grades except species 5/16(c) 1-1/4 6d 140 210 275 360 8d 140 210 275 360 Group 5 3/8 1-3/8 8d 160 240 310 410 10d 160 240 310(f) 410

(a) For framing of other species: (1) Find specific gravity for species of lumber in (d) Shears may be increased to values shown for 15/32-inch sheathing with the AFPA National Design Specification. (2) For common or galvanized box same nailing provided (1) studs are spaced a maximum of 16 inches o.c., or nails, find shear value from table above for nail size for actual grade. (3) (2) if panels are applied with strength axis across studs. Multiply value by the following adjustment factor: Specific Gravity Adjustment (e) Framing at adjoining panel edges shall be 3-inch nominal or wider, and Factor = [1 – (0.5 – SG)], where SG = specific gravity of the framing. This nails shall be staggered where nails are spaced 2 inches o.c. Check local adjustment shall not be greater than 1. code for variations of these requirements. (b) All panel edges backed with 2-inch nominal or wider framing. Install pan- (f) Framing at adjoining panel edges shall be 3-inch nominal or wider, and els either horizontally or vertically. Space nails maximum 6 inches o.c. along nails shall be staggered where 10d nails having penetration into framing of intermediate framing members for 3/8-inch and 7/16-inch panels installed more than 1-1/2 inches are spaced 3 inches o.c. Check local code for varia- on studs spaced 24 inches o.c. For other conditions and panel thicknesses, tions of these requirements. space nails maximum 12 inches o.c. on intermediate supports. Fasteners shall be located 3/8 inch from panel edges. (g) Values apply to all-veneer plywood APA RATED SIDING panels only. Other APA RATED SIDING panels may also qualify on a proprietary basis. APA (c) 3/8-inch or APA RATED SIDING 16 oc is minimum recommended when RATED SIDING 16 oc plywood may be 11/32 inch, 3/8 inch or thicker. applied direct to framing as exterior siding. Thickness at point of nailing on panel edges governs shear values.

Typical Layout for Shear Walls

Load Framing Blocking Framing

Shear wall boundary Foundation resistance

51 ROOF CONSTRUCTION APA Panel Roof Sheathing APA APA The recommendations for roof THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION sheathing in Table 24 apply to APA RATED SHEATHING RATED SHEATHING RATED SHEATHING Exposure 1, 24/16 7/16 INCH 40/20 19/32 INCH SIZED FOR SPACING SIZED FOR SPACING Exposure 2 or Exterior, and APA EXPOSURE 1 EXPOSURE 1 000 000 PRP-108 HUD-UM-40 PS 2-92 SHEATHING STRUCTURAL I RATED SHEATHING PRP-108 HUD-UM-40 Exposure 1 or Exterior. Uniform load deflection limits are 1/180 of span APA APA THE ENGINEERED THE ENGINEERED under live load plus dead load, and WOOD ASSOCIATION WOOD ASSOCIATION

1/240 under live load only. Special RATED SHEATHING RATED SHEATHING 48/24 23/32 INCH STRUCTURAL I 15/32 INCH conditions, such as heavy concentrated SIZED FOR SPACING 32/16 EXTERIOR SIZED FOR SPACING loads, may require constructions in 000 EXPOSURE 1 PS 1-95 C-C PRP-108 000 excess of these minimums, or allowable PS 1-95 C-D PRP-108 live loads may have to be decreased for dead loads greater than 10 psf, such as However, using fewer supports with tile roofs. Panels are assumed continu- thicker panels – e.g. 23/32- or 3/4-inch ous over two or more spans with the 48/24 panels over framing 48 inches long dimension or strength axis on center – is also cost-effective for across supports. long-span flat or pitched roofs. Recommended live loads are given in Note: The Span Rating in the trademark applies Table 24. Nailing recommendations are when the long panel dimension or strength axis is across supports unless the strength axis is other- given in Table 26. Recommended nail wise identified. schedules for high wind zones are described in APA Data File, Roof Good performance of built-up, Sheathing Fastening Schedules for Wind single-ply, or modified bitumen roofing Uplift, Form T325, available from APA. applied on low slope roofs requires a When support spacing exceeds the stiffer deck than does prepared roofing maximum length of an unsupported applied on pitched roofs. Although edge (see Table 24), provide adequate APA Span-Rated panels used as roof blocking, tongue-and-groove edges, or sheathing at maximum span are other edge support such as panel clips. adequate structurally, an upgraded Some types of panel clips, in addition to system is recommended for low slope edge support, automatically assure roofs. Table 25 provides recommended proper panel spacing. When required, maximum spans for low slope roof use one panel clip per span, except use decks. Recommended live loads can two clips for 48-inch or longer spans. be determined from Table 24, and mini- mum fastener requirements are given in Note: Gluing of roof sheathing to framing is not Table 26. Increased nail schedules may recommended, except when recommended by the adhesive manufacturer for roof sheathing that be required in high wind zones. already has been permanently protected by roofing. APA RATED SHEATHING is equally effective under built-up roofing, asphalt The Code Plus Roof or fiberglass shingles, tile roofing, or The Code Plus roof is designed to better wood shingles or shakes. Roof trusses resist wind and snow loads. The solid spaced 24 inches on center are widely panel roof sheathing also protects the recognized as the most economical structure from wind-driven rain and construction for residential roofs. snow – a typical long-term cause of

52 TABLE 24 RECOMMENDED UNIFORM ROOF LIVE LOADS FOR APA RATED SHEATHING(c) AND APA RATED STURD-I-FLOOR WITH STRENGTH AXIS PERPENDICULAR TO SUPPORTS(e) Maximum Span (in.) Allowable Live Loads (psf)(d) Panel Minimum Panel Spacing of Supports Center-to-Center (in.) Span Thickness With Edge Without Edge Rating (in.) Support(a) Support 12 16 20 24 32 40 48 60 APA RATED SHEATHING(c) 12/0 5/16 12 12 30 16/0 5/16 16 16 70 30 20/0 5/16 20 20 120 50 30 24/0 3/8 24 20(b) 190 100 60 30 24/16 7/16 24 24 190 100 65 40 32/16 15/32, 1/2 32 28 325 180 120 70 30 40/20 19/32, 5/8 40 32 — 305 205 130 60 30 48/24 23/32, 3/4 48 36 — — 280 175 95 45 35 60/32(g) 7/8 60 48 — — — 305 165 100 70 35 APA RATED STURD-I-FLOOR(f) 16 oc 19/32, 5/8 24 24 185 100 65 40 20 oc 19/32, 5/8 32 32 270 150 100 60 30 24 oc 23/32, 3/4 48 36 — 240 160 100 50 30 25 32 oc 7/8 48 40 — — 295 185 100 60 40 48 oc 1-3/32, 1-1/8 60 48 — — — 290 160 100 65 40

(a) Tongue-and-groove edges, panel edge clips (one midway between each (d) 10 psf dead load assumed. support, except two equally spaced between supports 48 inches on center or (e) Applies to panels 24 inches or wider applied over two or more spans. greater), lumber blocking, or other. For low slope roofs, see Table 25. (f) Also applies to C-C Plugged grade plywood. (b) 24 inches for 15/32-inch and 1/2-inch panels. (g) Check with supplier for availability. (c) Includes APA RATED SHEATHING/CEILING DECK. Note: Shaded construction meets Code Plus recommendations.

TABLE 25 RECOMMENDED MAXIMUM SPANS FOR APA PANEL ROOF DECKS FOR LOW SLOPE ROOFS(a)(Panel strength axis perpendicular to supports and continuous over two or more spans) Minimum Nominal Panel Clips Panel Thickness Minimum Maximum Span Per Span(b) Grade (in.) Span Rating (in.) (number)

15/32 32/16 24 1

APA 19/32 40/20 32 1 RATED SHEATHING 23/32 48/24 48 2

7/8 60/32 60 2

19/32 20 oc 24 1 APA RATED 23/32 24 oc 32 1 STURD-I-FLOOR 7/8 32 oc 48 2

(a) Low slope roofs are applicable to built-up, single-ply and modified bitumen roofing systems. For guaranteed or warranted roofs contact membrane manufacturer for acceptable deck. (b) Edge support may also be provided by tongue-and-groove edges or solid blocking.

53 ROOF CONSTRUCTION

callbacks – and serves as a stable surface for construction workers. Requirements TABLE 26 are as follows: RECOMMENDED MINIMUM FASTENING SCHEDULE FOR APA PANEL ROOF SHEATHING (Increased nail schedules may be required in high wind zones.) 1. Apply APA RATED SHEATHING with Nailing(c)(d) a minimum Span Rating of 32/16 to Panel Thickness(b) Maximum Spacing (in.) roof framing spaced 24 inches o.c., or (in.) Size Supported Panel Edges(e) Intermediate 2. Apply APA RATED SHEATHING with 5/16 - 1 8d 6 12(a) 1-1/8 8d or 10d 6 12(a) a minimum Span Rating of 24/16 to roof framing spaced 16 inches o.c. (a) For spans 48 inches or greater, space nails (c) Use common smooth or deformed shank 6 inches at all supports. nails with panels to 1 inch thick. For 1-1/8-inch 3. Provide adequate ventilation. Meet (b) For stapling asphalt shingles to 5/16-inch and panels, use 8d ring- or screw-shank or 10d thicker panels, use staples with a 15/16-inch common smooth-shank nails. or exceed your local code requirements minimum crown width and a 1-inch leg length. (d) Other code-approved fasteners may be used. Space according to shingle manufacturer’s (e) Fasteners shall be located 3/8 inch from for ventilation. recommendations. panel edges. 4. Fasten roof sheathing with 8d nails for panels 1 inch thick or less, 8d

deformed shank or 10d common for FIGURE 21 thicker panels, or other code-approved APA PANEL ROOF SHEATHING fasteners. Space nails 6 inches at sup- APA RATED SHEATHING Stagger end joints (optional) Note: ported edges and 12 inches at interme- Cover diate supports. Recommended nail 1/8" spacing is panel sheathing as soon as possible with recommended at all schedules for high wind zones are clip roofing felt for edge and end joints extra protection described in APA Data File, Roof unless otherwise against excessive moisture prior to Sheathing Fastening Schedules for Wind indicated by panel roofing application. manufacturer Uplift, Form T325, available from APA. Note: Panel clip or For pitched roofs, place screened surface or side 5. Leave a 1/8-inch space at all end and tongue-and-groove with skid-resistant coating edge joints to allow for panel expansion. edges if required up if OSB panels are used. Keep roof surface free of Asphalt or wood shingles dirt, sawdust and debris, Preframed Roof Panels and wear skid-resistant or shakes. Follow roofing shoes when installing Spans of 8 to 12 feet are usually the manufacturer’s recommen- roof sheathing. dations for roofing felt. most practical with preframed panel Note: Protect edges of Exposure 1 For buildings with conventionally framed roofs (trusses or ), construction, although spans to 30 feet limit the length of continuous sections of roof area to 80 feet panels against exposure to maximum during construction, to allow for accumulated expansion are not uncommon. Unsanded 4x8-foot weather, or use Exterior in wet weather conditions. Omit roof sheathing panels in each panel starter strip course of sheathing between sections, and install “fill in” panels APA panels with stiffeners preframed at later to complete roof deck installation prior to applying roofing. 16 or 24 inches on center (Figure 22) are common. The long dimension or strength axis of panel typically runs supports may require edge support such parallel to supports. Stiffeners and roof APA APA as panel clips or cleats between stiffen- THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION provide support for all panel ers at midspan in accordance with RATED SHEATHING RATED SHEATHING edges. Minimum nailing requirements Table 24. Recommendations in Table 27 24/16 7/16 INCH 24/16 7/16 INCH SIZED FOR SPACING SIZED FOR SPACING for preframed panels are the same as for EXPOSURE 1 EXPOSURE 1 are based on long dimension or strength 000 000 PRP-108 HUD-UM-40 STRUCTURAL I RATED roof sheathing. axis of the panel parallel to supports. DIAPHRAGMS-SHEAR WALLS PANELIZED ROOFS PRP-108 HUD-UM-40 In preframed panels 8x8 feet or larger Deflection limits are 1/180 of the span (Figure 23), the panel strength axis may for total load; 1/240 for live load only. run either parallel or perpendicular to See Table 28 for design information on stiffeners spaced 16 or 24 inches on stiffeners for preframed panels. Nailing center. Placing the strength axis across requirements for preframed panels are the same as for roof sheathing.

54 TABLE 27 RECOMMENDED ROOF LOADS (PSF) FOR APA RATED SHEATHING WITH STRENGTH AXIS PARALLEL TO SUPPORTS(e)(f) (OSB, composite and 5-ply/5-layer plywood panels unless otherwise noted) Maximum Load at Maximum Span Thickness Span Panel Grade (in.) Span Rating (in.) Live Total 7/16 24/0, 24/16 24(d) 20 30 APA 15/32 32/16 24 35(a) 45(a) STRUCTURAL I 1/2 32/16 24 40(a) 50(a) RATED 19/32, 5/8 40/20 24 70 80 SHEATHING 23/32, 3/4 48/24 24 90 100

7/16(b) 24/0, 24/16 16 40 50 (b) (d) APA 15/32 32/16 24 20 25 (b) (d) RATED 1/2 24/0, 32/16 24 25 30 (c) (c) SHEATHING 19/32 40/20 24 40 50 5/8 32/16, 40/20 24 45(c) 55(c) 23/32, 3/4 40/20, 48/24 24 60(c) 65(c)

(a) For 4-ply plywood marked PS 1, reduce load by 15 psf. (d) Solid blocking recommended at panel ends for 24-inch span. (b) Composite panels must be 19/32 inch or thicker. (e) For guaranteed or warranted roofs, contact membrane manufacturer for (c) For composite and 4-ply plywood panels, reduce load by 15 psf. acceptable deck. (f) Provide edge support.

FIGURE 22 FIGURE 23 PREFRAMED ROOF PANEL PREFRAMED ROOF PANEL (4' x 8' – APA Structural Panels (8' x 8' or larger – APA Structural Panels Strength Axis Parallel to Supports) Strength Axis Perpendicular to Supports)

Metal hanger Metal purlin hanger

Main supporting glulam member Main supporting glulam member Roof purlin Strength axis 8' o.c. (typical) APA structural panels

Strength axis Glulam purlin

Adjacent preframed panel APA structural panels Panel clips or other edge Stiffeners 16" o.c. or 24" o.c. support if required, or single large-sized panels

Glulam purlin Stiffeners of adjacent preframed panel Metal joist hangers Stiffeners 16", 20", Metal joist hangers 24", 32" or 48" o.c.

55 ROOF CONSTRUCTION

TABLE 28 STIFFENER LOAD-SPAN TABLES FOR PREFRAMED APA PANEL ROOF DECKS -Larch Allowable Roof Live Load (psf)(a) Center-to Stiffener Center Size Select Structural No. 1 & Btr No. 1 No. 2 Purlin and Strength(d) Strength(d) Strength(d) Strength(d) Spacing(b) Spacing (ft.) (in.) Defl.(c) 1.15 1.25 Defl.(c) 1.15 1.25 Defl.(c) 1.15 1.25 Defl.(c) 1.15 1.25 2 x 4@16 37 67 73 35 51 57 33 41 46 31 36 40 2 x 4@ 24 23 41 46 21 31 34 19 24 27 18 21 23 8 2 x 6@16 144 154 168 136 121 133 129 99 109 121 88 97 2 x 6@24 96 99 109 91 78 85 86 63 69 81 56 61 2 x 6@32 72 61 68 68 47 52 64 38 42 61 33 37

Southern Pine Allowable Roof Live Load (psf)(a) Center-to Stiffener Center Size Select Structural No. 1 Dense No. 1 No. 2 Purlin and Strength(d) Strength(d) Strength(d) Strength(d) Spacing(b) Spacing (ft.) (in.) Defl.(c) 1.15 1.25 Defl.(c) 1.15 1.25 Defl.(c) 1.15 1.25 Defl.(c) 1.15 1.25 2 x 4@16 35 87 96 35 58 64 33 53 59 31 41 46 2 x 4@24 21 55 60 21 35 39 19 32 36 18 24 27 8 2 x 6@16 136 205 223 136 137 150 129 129 141 121 95 104 2 x6@24 91 133 146 91 88 97 86 83 91 81 60 66 2 x 6@32 68 83 91 68 54 60 64 50 56 61 36 40

(a) Final allowable load is the lesser of the loads as determined by deflection (c) Deflection limitations: Span/240 under live load only; Span/180 under and stress. total load, assuming a dead load of 10 psf. (b) Actual span of stiffeners taken as 3-1/2 inches less than center-to-center (d) Loads limited by stress are based on two conditions of duration of spacing of purlins. load: 2 months, such as for snow (1.15); and 7 days (1.25); includes effects of 10 psf dead load.

Long Span Systems structures with contoured or steeply use APA C-C PLUGGED Exterior. Both preframed panel systems and pitched roof surfaces exposed to view. Tongue-and-groove plywood (1/2 inch direct application of sheathing to The plywood thickness and span or thicker) or lumber blocking at panel secondary or primary framing are recommendations in Table 29 for edges is recommended. A 1/8-inch common approaches in long span roof plywood under special coatings assume space is recommended at all edge and construction. Bay spacing and type of installation with the long dimension or end joints unless otherwise indicated by framing govern the choice. strength axis of the panel perpendicu- panel manufacturer. If high-performance Experience shows that panels over lar to supports and liquid coatings coatings are to be used for finish, check supports 48 inches on center often applied directly to the plywood. Check coating manufacturer’s recommenda- yield maximum economy. Panels with local building codes for any required tions for panel joint treatment. Nail size, a Span Rating of 48/24 are good for at deviations from these recommendations. type and spacing recommendations are least 35 psf snow load and meet the Allowable roof live load is based on the also given in Table 29. requirements for most guaranteed or same deflection criteria as described in Grades recommended above should warranted roofs. Table 24 for APA panel roof sheathing. also be specified when the structural Figure 24 illustrates typical connections Exterior plywood is recommended for wood deck is to be overlaid with a sepa- for engineered flat roof members. use under special coatings for roofs. rate plywood layer to serve as substrate Where the coating requires a very for special roof coatings. A 1/8-inch Plywood Under Special Coatings smooth base, use APA A-C Exterior or space is recommended at all edge and Chemical coatings for roofs have APA B-C Exterior plywood. Where end joints unless otherwise indicated by increased the range of design possibil- maximum smoothness is not essential, panel manufacturer. Although minimum ities, particularly in larger commercial 1/4-inch plywood may be used over

56 TABLE 29 PLYWOOD THICKNESS AND MAXIMUM SPANS FOR ROOF DECKS UNDER SPECIAL COATINGS(c) Minimum Maximum Support Spacing (in.) Maximum Nail Spacing (in.) Plywood Thickness Nail Type & Supported Intermediate Grade (in.) Group 1 Groups 2 & 3 Group 4 Size(b) Panel Edges Supports 8d common smooth(a) 11/32 16 ——or ring- or screw-shank 612 8d common smooth(a) APA A-C EXT 15/32, 1/2 24 24 16 or ring- or screw-shank 612 APA B-C EXT APA C-C PLUGGED EXT 19/32, 5/8 32 24 24 8d ring- or screw-shank 6 12 23/32, 3/4 40 32 32 8d ring- or screw-shank 6 12 7/8 48 40 40 8d ring- or screw-shank 6 12(d)

(a) Use only deformed-shank nails for curved surfaces. (c) All panels will support at least 30 psf live load plus 10 psf dead load (b) Nail type, size and spacing may vary for diaphragm designs. at maximum span. (d) For spans 48 inches or greater, space nails maximum 6 inches at all supports.

structural decks, 15/32 inch or thicker panels should be considered for best FIGURE 24 performance over uneven surfaces or TYPICAL CONNECTIONS TO ENGINEERED FLAT ROOF MEMBERS when rain or high humidity is antici- Panels Nailed to Wood I-Joist Panels Nailed to Open-Web pated prior to application of roof Parallel-Chord Wood coating. Use corrosion-resistant fasten- ers sized and spaced as recommended Wood flange APA panel deck in Table 8. Wood I-joist Wood chord Diagonal wood web APA Panel Soffits Wood structural Recommended spans for open and panel web Metal truss plate closed APA panel soffits are given in Panels Nailed to Nailer Panels Nailed to Glulam Beam Tables 30 and 31. The recommenda- Bolted to Steel Joist tions in Table 30 for open soffits also apply to combined roof/ceiling APA panel deck APA panel deck construction. Panels are assumed Common nails Glulam beam continuous over two or more spans Wood nailer* with the long dimension or strength Carriage bolt axis across supports for both applica- or lag screw tions. For appearance purposes in open *May be installed Bar joist flange across joists (good soffit construction, provide blocking, for nonmodular tongue-and-groove edges, or other Bar joist web joist spacing). suitable edge support. Panels will sup- port at least 30 psf live load, plus Only Exterior panels should be used for Although unsanded and touch-sanded 10 psf dead load. closed soffits. grades of plywood are often used for For open soffit and nonstructural ceiling applications such as soffits, optimum At eaves where Exposure 1 sheathing is construction, panels designated appearance and finish performance is used for roof decking, protect panel Exposure 1 are recommended as a mini- attained by using panels with textured edges against direct exposure to the mum (check local building code) where or sanded A-grade faces. For panel weather with fascia trim. appearance is not a major consideration. grades other than APA RATED SIDING

57 ROOF CONSTRUCTION

TABLE 30 APA PANELS FOR OPEN SOFFIT OR FOR COMBINED ROOF DECKING-CEILING(a)(b) (Strength axis across supports. For APA RATED SHEATHING, where appearance is not a major concern, see Table 24.) Maximum Span Panel Description Species Group (inches) (All panels Exterior or Exposure 1) for Plywood

15/32" APA RATED SIDING 303 1, 2, 3, 4 16 15/32" APA MDO, Sanded and Touch-Sanded Plywood 1, 2, 3, 4

15/32" APA RATED SIDING 303 1 15/32" APA MDO, Sanded and Touch-Sanded Plywood 1, 2, 3 24 19/32" APA RATED SIDING 303 1, 2, 3, 4 19/32" APA MDO, Sanded and Touch-Sanded Plywood 1, 2, 3, 4 APA RATED STURD-I-FLOOR 16 oc —

19/32" APA RATED SIDING 303 1 19/32" APA MDO, Sanded and Touch-Sanded Plywood 1 32 23/32" APA Textured Plywood(c) 1, 2, 3, 4 23/32" APA MDO, Sanded and Touch-Sanded Plywood 1, 2, 3, 4 APA RATED STURD-I-FLOOR 20 oc —

48 1-1/8" APA Textured Plywood(c) 1, 2, 3, 4 APA RATED STURD-I-FLOOR 48 oc —

(a) All panels will support at least 30 psf live load plus 10 psf dead load at (b) For appearance purposes, blocking, tongue-and-groove edges or other maximum span. suitable edge supports should be provided. (c) Also see Table 24 for APA RATED SHEATHING/CEILING DECK.

TABLE 31 APA PANELS FOR CLOSED SOFFIT OR FOR NONSTRUCTURAL CEILING(a)(c) (Strength axis across supports) Maximum Span (in.) Nominal Nail Size All Edges Supported Panel Thickness Species Group and Type(a)

(b) 24 11/32" APA 6d nonstaining All box or casing 32 15/32" APA(b) Species Groups

(b) 8d nonstaining 48 19/32" APA box or casing

(a) Space nails maximum 6 inches at panel edges and 12 inches at (b) Any suitable grade panel which meets appearance requirements – Exterior intermediate supports for spans less than 48 inches; 6 inches at all supports for closed soffits, Exposure 1 or Exterior for nonstructural ceiling. for 48-inch spans. (c) For appearance purposes, blocking, tongue-and-groove edges or other suitable edge supports should be provided.

58 struction (see page 64), shear values for FIGURE 25 19/32" panels are used. Blocked shear OPEN SOFFIT values for 1-1/8" panels may be obtained by specifying stapled T&G APA RATED SHEATHING edges. Staples shall be 16 , 1" long with a 3/8" crown, driven through the T&G edges 3/8" from the joint so as to Strength axis Shim at each for flush penetrate the tongue. Staples shall be joint at change of panel thickness if necessary spaced at one-half of the boundary nail spacing for Cases 1 and 2, and at one- Any appropriate APA Exterior or third the boundary nail spacing for Case Exposure 1 panel grade and 3 through 6, as illustrated in Table 32. thickness for desired appearance and load-carrying capacity (see Table 32 gives panel and fastening Tables 24 and 30) recommendations for roof diaphragms. Panels and framing are assumed already designed for perpendicular loads. To design a diaphragm, follow these steps: FIGURE 26 CLOSED SOFFIT 1. Determine lateral loads and resulting shears. APA RATED SHEATHING 2. Determine nailing schedule Protect edges of Exposure 1 sheathing (Table 32). Consider load direction against exposure to weather with respect to joints. Any appropriate grade of 3. Compute chord stress due to Exterior panels for soffit bending moment. Provide adequate (see Table 31) splices. Check deflection. Check Continuous screened vent Strength axis anchorage of boundary framing or louvered vent (e.g., chords) to walls. Leave 1/8" space at all panel end and edge joints. Support all panel edges. For information about developing higher diaphragm shears than shown in Table 32, See Diaphragms and Shear 303, top-quality acrylic latex house also function as an engineered Walls, APA Form L350. paint systems provide best performance diaphragm to resist high wind and (see page 48). Face-checking (separa- seismic loading. A diaphragm’s ability APA APA THE ENGINEERED THE ENGINEERED tions between fibers parallel to the grain to function effectively as a beam, trans- WOOD ASSOCIATION WOOD ASSOCIATION of the face veneer) can be expected on ferring lateral loads to shear walls, is RATED SHEATHING RATED SHEATHING 40/20 19/32 INCH STRUCTURAL I 15/32 INCH non-overlaid plywood which is exposed related to the quality of the connections. SIZED FOR SPACING 32/16 EXPOSURE 1 SIZED FOR SPACING 000 EXPOSURE 1 to the outdoors, even when finished. If Nailing is critical since shears are PRP-108 HUD-UM-40 000 PS 1-95 C-D PRP-108 a smooth, check-free surface is desired, transmitted through these fasteners. use Medium Density Overlay Common nails provide required APA APA (MDO) plywood. strength. Other nail types may be used THE ENGINEERED THE ENGINEERED WOOD ASSOCIATION WOOD ASSOCIATION

when their lateral bearing values are RATED SHEATHING RATED SHEATHING APA Panel Roof Diaphragms considered in the design. Load-carrying 24/0 3/8 INCH 24/16 7/16 INCH SIZED FOR SPACING SIZED FOR SPACING With only slight design modifications, EXPOSURE 1 EXPOSURE 1 capacity is highest when the diaphragm 000 000 any APA panel roof deck system STRUCTURAL I RATED PS 2-92 SHEATHING DIAPHRAGMS-SHEAR WALLS PRP-108 HUD-UM-40 is blocked. Where 1-1/8" roof panels are PRP-108 HUD-UM-40 described in the previous sections will desired, such as for Heavy Timber con-

59 ROOF CONSTRUCTION

TABLE 32 RECOMMENDED SHEAR (POUNDS PER FOOT) FOR HORIZONTAL APA PANEL DIAPHRAGMS WITH FRAMING OF DOUGLAS-FIR, LARCH OR SOUTHERN PINE(a) FOR WIND OR SEISMIC LOADING Blocked Diaphragms Unblocked Diaphragms Nail Spacing (in.) at Nails Spaced 6" max. at diaphragm boundaries Supported Edges(b) (all cases), at continuous panel edges parallel to load (Cases 3 & 4), and at all panel edges (Cases 5 & 6)(b) Minimum 642-1/2(c) 2(c) Case 1 (No Minimum Minimum Nominal unblocked Nail Nominal Width of Nail Spacing (in.) at edges or All other Penetration Panel Framing other panel edges continuous configurations Common in Framing Thickness Member (Cases 1, 2, 3 & 4)(b) joints parallel (Cases 2, 3, Panel Grade Nail Size (inches) (inch) (inches) to load) 4, 5 & 6) 6643 6d(e) 1-1/4 5/16 2 185 250 375 420 165 125 3 210 280 420 475 185 140 APA 8d 1-3/8 3/8 2 270 360 530 600 240 180 STRUCTURAL I 3 300 400 600 675 265 200 grades 10(d) 1-1/2 15/32 2 320 425 640 730 285 215 3 360 480 720 820 320 240

5/16 2 170 225 335 380 150 110 3 190 250 380 430 170 125 6d(e) 1-1/4 3/8 2 185 250 375 420 165 125 3 210 280 420 475 185 140 APA RATED SHEATHING 3/8 2 240 320 480 545 215 160 APA RATED 3 270 360 540 610 240 180 STURD-I- FLOOR 8d 1-3/8 7/16 2 255 340 505 575 230 170 3 285 380 570 645 255 190 and other APA grades 15/32 2 270 360 530 600 240 180 except Species 3 300 400 600 675 265 200 Group 5 15/32 2 290 385 575 655 255 190 3 325 430 650 735 290 215 10d(d) 1-1/2 19/32 2 320 425 640 730 285 215 3 360 480 720 820 320 240

(a) For framing of other species: (1) Find specific gravity for species of lumber in (d) Framing at adjoining panel edges shall be 3-in. nominal or wider, and the AFPA National Design Specification. (2) Find shear value from table above nails shall be staggered where 10d nails having penetration into framing of for nail size for actual grade. (3) Multiply value by the following adjustment fac- more than 1-5/8 inches are spaced 3 inches o.c. tor: Specific Gravity Adjustment Factor = [1 – (0.5 – SG)], where SG = specific (e) 8d is recommended minimum for roofs due to negative pressures of gravity of the framing. This adjustment shall not be greater than 1. high winds. (b) Space nails maximum 12 inches o.c. along intermediate framing members Notes: Design for diaphragm stresses depends on direction of continuous (6 in. o.c. when supports are spaced 48 in. o.c. or greater). Fasteners shall be panel joints with reference to load, not on direction of long dimension or located 3/8 inch from panel edges. strength axis of sheet. Continuous framing may be in either direction for (c) Framing at adjoining panel edges shall be 3-in. nominal or wider, and nails blocked diaphragms. shall be staggered where nails are spaced 2 inches o.c. or 2-1/2 inches o.c.

Case 1 Case 4 Case 5 Case 2 Blocking, Case 3 Blocking, Blocking, Case 6 Load Framing Load Load Framing Load Load Load Framing if used if used if used

Continuous panel joints Diaphragm boundary Continuous panel joints Continuous panel joints

60 BUILDING REQUIREMENTS RELATED AND Fire-resistant Construction fire-resistive rating for exterior walls PANEL SYSTEMS Protected Construction applies only to the inside of the wall Protected construction includes when separation to the property line is typical floor-ceiling, roof-ceiling or wall greater than 5 feet. In this common assemblies with wood structural panels situation, the gypsum sheathing can be fastened to wood or steel framing, and a omitted under the siding as noted in fire-resistive material such as gypsum Figure 28. wallboard, or mineral acoustical Fire-rated protected wall assemblies will tile added to give primary protection to qualify for the one-hour rating if other framing. The structural panels slow materials are added over the fire-resistive flame passage and temperature rise materials. For example, APA RATED while reinforcing supports against SIDING panels or lap siding may be collapse under load. attached to the outside of a rated wall Assemblies are rated in fire tests by without impairing the rating. Underwriters Laboratories (U.L.) and Roof Coverings other agencies. Over 40 floor-ceiling The fire resistance ratings of roofing (and/or roof-ceiling) systems using materials are listed as Class A, B, or C wood structural panels are described in in descending order of fire protection the U.L. Fire Resistance Directory. They afforded. Their use is prescribed by are accepted as rated constructions by building codes, and also affects insur- most building codes. Two examples of ance rates. Untreated APA RATED one-hour-rated floor-ceiling assemblies SHEATHING panels are recognized are shown in Figure 27; several two- as a structural roof deck substrate for hour-rated wood framed assemblies also rated roof coverings. For individual are described in the U.L. Directory. requirements, see the U.L. Roofing Building Requirements Materials and Systems Directory. In many fire-resistant floor-ceiling Wall and Ceiling Paneling assemblies, a two-layer floor system The Flame Spread Classification of (15/32-inch subfloor and 19/32-inch materials used for interior wall and underlayment) is used, although several ceiling finish (and occasionally for other have single-layer 5/8-inch or thicker applications) is usually limited by combination subfloor-underlayment building codes for certain occupancies. panels. Any finish floor material may be Tests have shown that untreated APA used. Most codes permit omission of wood structural panels will develop the top panel layer in roof assemblies. flame spread index and smoke index Plywood siding or wall sheathing in values of 200 or less, which puts them combination with gypsum sheathing in a Class III (or C) category. and wallboard on studs is recognized by Panels are therefore suitable as interior code officials for one-hour load-bearing finish for most applications. Certain exterior walls. A typical example – more restrictive locations, such as APA RATED SIDING over 5/8-inch Type exitways, require a Class I or Class II X gypsum sheathing attached to 2x rating which can be achieved by the studs 16 or 24 inches on center – is use of fire-retardant-treated plywood. illustrated in Figure 28, page 63. Under (See page 15.) two of the model building codes, the

61 BUILDING REQUIREMENTS AND RELATED PANEL SYSTEMS

Structural Glued Laminated FIGURE 27 Timber (Glulam) ONE-HOUR FIRE-RATED COMBUSTIBLE FLOOR/CEILING A structural member’s fire resistance is (OR ROOF/CEILING) ASSEMBLIES measured by the time it can support its Some rated assemblies incorporate proprietary products. When designing and specifying, check the Underwriters Laboratories Fire Resistance Directory for complete details on a design load during a fire. An exposed particular assembly. A change in details may affect fire resistance of the assembly. beam or column sized for a minimum (a) 1. Two-layer floor systems with joists. For details, see U.L. Design Nos. L001, one-hour fire resistance will support its L003, L004, L005, L006, L201, L202, L206, L208 (1-1/2 hr), L209, L210, L211 (2 hr), L212, L501, L502, L503, L505 (2 hr), L511 (2 hr), L512, L514, L515, L516, L519, full design load for at least one hour L522, L523, L525, L526, L533, L535, L536 (2 hr), L537, L541 (2 hr) and L545. Also see U.L. Designs No. L524 and L527 (1-1/2 hr single layer) with steel joists spaced 24" o.c., during standard fire test conditions and L521 with wood trusses spaced 24" o.c. which simulate an actual fire.

Building paper Beams. Glulam beams 6-3/4" and 8-3/4" wide can be adapted to a one- 15/32" APA hour fire rating in accordance with plywood subfloor(b) procedures recognized by the model codes. For these widths, there is a Joists 16" o.c. (2x10s min.) minimum depth for a one-hour fire rating. The minimum depth increases 19/32" T&G 5/8" Type X or proprietary* APA plywood when the design calls for the beam to be Type X gypsum wallboard underlayment(b)(c) exposed on four rather than three sides. ceiling; resilient channels (Most codes do not required in some assemblies require the top layer of two-layer See Table 33. rated assemblies when used for roofs.) To adapt beams whose dimensions qualify them for one-hour fire rating, the basic layup is modified as shown in 2. Single-layer floor systems with wood I-joists or trusses. For details, see U.L. Design Nos. L528, L529, L534, L542 and L544 (shown). Also see U.L. Design No. L513 Figure 29. One core lamination from for single-layer floor system with lumber joists spaced 24" o.c. the center of the beam is required by an 23/32" T&G Construction additional tension lamination. APA plywood(b)(c) adhesive at trusses and T&G edges Columns. Column length determines the minimum size for one-hour ratings. The column size needed for a one-hour fire rating is determined by calculating the l/d and then using the appropriate minimum dimensions; see Table 34. Columns generally need no special Resilient channels layup to qualify for a one-hour fire spaced 16" o.c. rating. For both 8-3/4" and 10-3/4" Wood I-joists or trusses 24" o.c. widths, all columns meeting the mini- 1/2" proprietary* Type X mum size standard satisfy the one-hour *For proprietary names see latest gypsum wallboard ceiling U.L. Fire Resistance Directory (2 layers) fire rating requirement. Note: (a) Substitution of 1-1/8" APA RATED STURD-I-FLOOR 48 oc for the combination of subfloor, paper, As with all structural framing, final and underlayment is often allowed. Check with local Building Official. specifications of members designed to (b) Tests have shown that substitution of OSB or composite APA RATED SHEATHING subfloor and APA RATED STURD-I-FLOOR underlayment for the plywood panels in rated assemblies will not jeopardize have one-hour fire resistance should fire-resistance ratings. Substitution is based on equivalent panel thickness, except that 7/16" OSB subfloor panels may be used in place of 15/32" plywood subfloor panels in two-layer assemblies. be carefully checked by a professional OSB panels are listed as alternates to plywood subflooring or finish flooring in U.L. Design Nos. L501, L503, L505 (2hr), L508, L511 (2hr), L513, L514, L516, L521, L526, L528, L529, L532 (1-1/2 hr), engineer or architect to assure compli- L539, L540, L543, L544, L546, L548, L550, L551 and L552. ance with all local building codes. (c) Lightweight concrete or gypsum concrete floor topping permitted over single-layer floor or as alternate to plywood underlayment in many assemblies (check details).

62 Metal Connectors. In structures using FIGURE 28 one-hour rated glulams, supporting ONE-HOUR FIRE-RATED EXTERIOR LOAD-BEARING WALL ASSEMBLY(a) metal connectors and fasteners also must be designed to achieve a one-hour fire 2x4 studs all Mineral or glass fiber rating. A 1-1/2" covering of wood, 5/8" 16" or 24" o.c. insulation (optional) fire-rated (Type X) gypsum wallboard or any coating approved for a one-hour 5/8" Type X rating provides the needed protection. gypsum wallboard For further information, see EWS Technical Note EWS Y245, Calculating 5/8" Type X Fire Resistance of Glulam Beams and gypsum sheathing(b) Columns. APA RATED SIDING 16 or 24 oc (or panel sheathing) TABLE 33 ONE-HOUR FIRE-RATED GLULAM BEAMS – MINIMUM DEPTHS FOR (a) Generic, non-proprietary assembly based on GA File No. WP8105 listed in Gypsum Association Fire Resistance Design Manual, referenced in the model 6-3/4" AND 8-3/4" WIDE BEAMS building codes. Mineral or glass fiber batt insulation (optional). Minimum Depth (inches) (b) Exterior layer of gypsum sheathing not required under the National and Standard Building Codes, or the International Building Code, when separation is Beam Width 3 Sides 4 Sides greater than 5 feet. Check local provisions. See U.L. Design U356 in U.L. Fire (inches) Exposed Exposed Resistance Directory. 6-3/4 13-1/2 27

8-3/4 7-1/2 13-1/2 FIGURE 29 ONE-HOUR FIRE-RATED GLULAM BEAM (Layup for simple span)

TABLE 34 ONE-HOUR FIRE-RATED Compression lams at top GLULAM COLUMNS – MINIMUM DEPTHS FOR 8-3/4" AND 10-3/4" COLUMN WIDTHS Minimum Core lams in center Core lam from center Depth (inches) Column replaced by tension lam l/d Width 3 Sides 4 Sides added at bottom Criteria (in.) Exposed Exposed l/d>11 8-3/4 15 30 10-3/4 10-1/2 13-1/2 Tension lams at bottom l/d ≤ 11 8-3/4 9 12 10-3/4 7-1/2 10-1/2 l = column length in inches. d = column least cross-sectional dimension in inches.

63 BUILDING REQUIREMENTS AND RELATED PANEL SYSTEMS

Heavy Timber Construction Model building codes also recognize FIGURE 30 Heavy Timber wood construction HEAVY TIMBER ROOF CONSTRUCTION systems, which can simplify roof or floor Built-up roofing construction while providing superior fire resistance. Heavy Timber construction does not constitute 1-1/8" APA T&G wood structural one-hour fire resistance, however. panels with exterior glue (Exposure 1) – APA RATED STURD-I-FLOOR 48 oc typical Under fire conditions, large size timber Strength axis members develop a surface char layer which acts as insulation to slow the Structural glued laminated timber (glulam) or solid timber beams (4x6 minimum) burning process. In addition, Heavy Timber construction does not permit concealed wall or ceiling spaces where structural panels APA RATED SHEATH- fire can spread. Years of fire service ING/CEILING DECK panels can be TABLE 35 experience shows that the structural specified. DIMENSIONS OF COMPONENTS performance of Heavy Timber construc- FOR HEAVY TIMBER CONSTRUC- Heavy timber floors may also be con- tion systems under fire conditions is TION (TYPICAL CODE PROVISIONS) structed with 15/32-inch wood struc- markedly superior to most unprotected Heavy Timber construction is gener- tural panels over three-inch planks. ally defined in building codes and “noncombustible” (steel) structures. standards by the following minimum For additional information on sizes for the various members or See Table 35 for minimum structural portions of a building: fire-resistant construction, see APA member sizes required by model build- Design/ Construction Guide: Fire-Rated Inches, nominal ing codes for Heavy Timber construc- Systems, Form W305. Columns–supporting tion. Structural glued laminated timber floor loads ...... 8 x 8 Supporting roof and ceiling (glulams) also qualifies for Heavy Wind-resistive Roofs loads only ...... 6 x 8 Timber construction systems when Wind ratings are based on a roof Floor framing members conform to required sizes. system’s performance in wind uplift Beams and girders ...... 6 wide x 10 deep Insurance rating bureaus and all of the tests. Systems meeting U.L. require- Arches and model building codes accept 1-1/8-inch ments are assigned a semi-wind-resistive trusses ...... 8 in any dimension tongue-and-groove wood structural classification (Class 30 or 60) or Roof framing – not supporting floor loads panels with exterior glue (Exposure 1) fully-wind-resistive classification Arches springing from as an alternative to two-inch nominal (Class 90). grade ...... 6 x 8 lower half 6 x 6 upper half tongue-and-groove lumber decking in Many of the fire-rated assemblies also Arches, trusses, other heavy timber roof construction. can qualify for these ratings. Heavy framing springing from top of walls, etc...... 4 x 6 Typical construction (Figure 30) Timber usually is accorded semi-wind- Floor (covered with 1-inch consists of tongue-and-groove APA resistive recognition. nominal flooring, 15/32- RATED STURD-I-FLOOR 48 oc or 1/2-inch wood structural There are over 70 U.L. listed roofing/ panels, or other approved Exposure 1 (or 1-1/8-inch tongue-and- roof deck systems with plywood sheath- surfacing) groove APA RATED SHEATHING Splined or tongue-and- ing for fully-wind-resistive Class 90 groove ...... 3 Exposure 1 – Check local availability ratings. One of the systems, NM519, is Planks set on edge ...... 4 before specifying). Heavy timber beams illustrated in Figure 31. Another is Roof decks must be 4x6 minimum and are nor- Splined or tongue-and- NM520, a panelized roof deck of groove plank ...... 2 mally spaced 48 inches on center. For 15/32-inch APA RATED SHEATHING Plank set on edge ...... 3 an exposed ceiling with improved Tongue-and-groove 32/16 Exposure 1 plywood marked PS 1 wood structural panels ...... 1-1/8 appearance, 1-1/8-inch textured wood (CDX, 4 plies minimum, all-Group 1

64 species) on 2-inch nominal stiffeners spanning eight feet between purlins FIGURE 31 framed into glulam beams. See Figure 32 FULLY-WIND-RESISTIVE ROOF ASSEMBLY — U.L. CLASS 90 (NM519) for further information. This panelized Base sheet (U.L. Type Two-ply sheets (U.L. Type G1 asphalt glass fiber mat, roof is commonly used for seismic or G2 asphalt glass fiber 10 lb nominal) hot-mopped with surface flood coat(b) wind resistance, utilizing the diaphragm mat, 20 lb nominal)(b) 2" nominal Douglas-fir shear strength of the plywood. or southern pine fram- Plywood face grain ing spaced 24" o.c.

Other fully-wind-resistive Class 90 roof direction (a)

• • • maximum

•

• systems with proprietary metal roofing

• • • • • panels, using plywood or OSB panels •

as a roofing substrate over steel decking, • • • • •

• • • •

•

• • • • •

or as structural roof sheathing, also meet 15/32" APA RATED • • • • U.L. requirements. See Figure 33. SHEATHING 32/16 1/4"-wide Exposure 1 plywood tape (rows spaced For additional information, see APA marked PS 1 at 8-1/2" o.c. typ.) Design/Construction Guide: Nonresidential 8d common deformed shank 16-ga. x 7/8"-long coated nails, spaced 6" o.c. at panel ends Roof Systems, Form A310 and U.L. Roof staples spaced 4" o.c. typ. and 12" o.c. at interior supports Materials and Systems Directory. (a) Design in accordance with local building code requirements for roof loads and anchorage. All framing must have 2" nominal or greater width for plywood deck nailing. Noise Transmission Control (b) Install roofing base and ply sheets with roll direction parallel to plywood face While some attention to sound control grain directions. may be desirable in certain types of single-family residential buildings, it is mandatory in multifamily, commercial FIGURE 32 and industrial construction. FULLY-WIND-RESISTIVE ROOF ASSEMBLY — U.L. CLASS 90 (NM520) Selection of the correct noise-resistant surface and insulation assemblies is Roof purlins or trusses spaced 8' o.c.(a) 1/4"-wide rayon tape (rows spaced at 8-1/2" o.c.,(b) with 16-ga. x 7/8"-long based on Sound Transmission Two-ply sheets (U.L. Type G1 coated staples spaced 4" o.c.) Class (STC) and Impact Insulation asphalt glass fiber mat, 10 lb nominal) hot-mopped with Class (IIC). The STC rates a structural surface flood coat(c) assembly’s ability to reduce airborne Base sheet (U.L. Type G2 asphalt noise. Most authorities agree that a glass fiber mat, 20 lb nominal)(c) multi-occupancy residential floor or wall Plywood face should have an STC rating of at least 45, grain direction

• • • • •

• 2" nominal while over 50 is considered premium • •

• • •

• • •

Douglas-fir or • •

•

• • •

construction. Below 40, loud speech

•

• •

• southern pine fram-

• •

•

• •

• •

can be audible as a murmur and privacy • • ing spaced 24" o.c.

• •

10d (short or

• •

• • • and comfort are impaired. The level of diaphragm) common • background noise affects the choice nails, 4" o.c. at edges 15/32" APA RATED SHEATHING and 6" o.c. at interior 32/16 Exposure 1 plywood marked of STC. supports(b) PS 1 (4 plies minimum, all Group 1 The IIC ratings define the capacity to species) or 15/32" APA STRUC- TURAL I RATED SHEATHING 32/16 Steel joist hangers control impact noise and have replaced plywood marked PS 1 the earlier Impact Noise Rating (INR). In most cases, required IIC rating values (a) Trusses or I-joists used for purlins must have chords or flanges of 1-3/4" minimum depth for plywood deck nailing. are about the same as for STC. (b) For semi-wind-resistive assemblies (Class 60), plywood deck nailing spaced 6" o.c. at all supports and roofing base sheet attached with rayon tape rows spaced 11-1/3" o.c (c) Install roofing base and ply sheets with roll direction parallel to plywood face grain direction.

65 BUILDING REQUIREMENTS AND RELATED PANEL SYSTEMS

Figures 34 and 35 show only two of the many sound-resistant floor and FIGURE 33 wall assemblies that can be obtained METAL ROOFING PANELS — U.L. CLASS 90(a) with wood structural panels. Some APA RATED SHEATHING plywood per Metal roofing panels fastened to plywood floor-ceiling assemblies also qualify as PS 1 (min. 15/32" for framing spaced or framing with steel clips and screws fire-rated construction. 16" o.c.; 19/32", 5/8 or 3/4" for fram- ing spaced 24" o.c.) While many listed assemblies were tested using plywood, other APA OSB

• • Caulk or tape to • • • and composite structural-use panels • • • • • • seal joints (check • • • • No. 15 asphalt felt vapor • • • may be substituted on a thickness for • • • manufacturers’ • • • retarder – one or two layers

• • recommendations) • thickness basis. Because of their similar • (may be optional) • strength and stiffness properties and 24" max. slightly higher density, use of these products in lieu of plywood will not 8d deformed shank nails or 2x4 wood framing (joists bolted to steel purlins compromise the STC or IIC ratings of No. 8 x 2" screws @ 6" o.c. at spaced 48 - 60" o.c., or top chord of trusses), the tested systems. edges and 6" or 12" o.c. at 2x6 wood framing, or steel framing (min. 22 gage) interior supports (for steel For additional information, see APA framing, No. 6 x 1-1/4" or Design/Construction Guide: Noise-Rated No. 12 x 1-5/8" screws) Systems, Form W460. (a) Some rated assemblies and constructions incorporate OSB sheathing and proprietary products. When designing and specifying, check the Underwriters Laboratories (U.L.) Roofing Materials and Systems Directory (Category TGKX) for complete details on a particular assembly in U.L. Construction Nos. 200-500 (series). A change in details may affect the wind uplift classification of the assembly. FIGURE 34 NOISE-RESISTANT PARTY WALL STC = 46

FIGURE 35 3/8" APA RATED (a) SHEATHING applied NOISE-RESISTANT FLOOR ASSEMBLY vertically with 6d (Lightweight Concrete Over APA Panels) STC = 58; IIC = 73 common nails spaced 6" o.c. at 1-1/2" lightweight concrete on No.15 asphalt felt edges, 12" o.c. other framing. Nail heads Carpet and pad dimpled into panel. 5/8" APA RATED SHEATHING subfloor 1/2" gypsum wallboard applied vertically, joints staggered. Nail to framing with 8d nails spaced 12" o.c. Wood joists 16" o.c. Joists taped. 2x4 studs spaced 24” 24" o.c. staggered 5/8" gypsum wallboard 2x6 plate screwed to resilient top and bottom channels; joints taped

Resilient channels spaced 24" o.c.

(a) Also meets minimum construction requirements for one-hour fire-rated floor- ceiling assembly per Underwriters Laboratory (U.L.) Design No. L514. Ref. Geiger and Hamme, Inc. tests CCA-10MT and CCA-11MT (1972).

66 Energy Conservation Insulating Exterior Walls FIGURE 36 With adoption of more stringent regula- ENERGY-CONSERVING STURD-I-WALL ASSEMBLIES tions concerning building insulation, it is increasingly important to build walls APA RATED SIDING DIRECT TO STUDS to meet new requirements as efficiently 1/2" gypsum wallboard as possible. Installation of APA RATED Vapor retarder SIDING panels yields tight construction Batt insulation to minimize heat loss due to air infiltra- tion. Framed walls also can be easily Wood studs (2x4 with R11 or R15HD insula- tion or 2x6 with R19 or R21HD insulation) insulated to provide U values found in energy standards. Figure 36 illustrates APA RATED SIDING (11/32" or thicker) two construction options and their corresponding U values. One of the R Outside surface (15 mph wind) 0.17 assemblies uses APA RATED SIDING Insulation Minimum APA RATED SIDING 0.43–0.78 Option Average U Effective R = 1/U direct to studs, and one shows siding Batt insulation applied over rigid foam insulation. Option A – R11 11.00 A 0.100 10.01 Option B – R15HD (high density) 15.00 B 0.086 11.66 Option C – R19 18.00(a) Figure 36 shows the installation of the Option D – R21HD (high density) 21.00 C 0.065 15.36 vapor retarder on the inside of the wall 1/2" gypsum wallboard 0.45 D 0.060 16.70 framing for typical construction. Local Inside surface (still air) 0.68 climatic conditions, energy codes or standard construction practices may APA RATED SIDING OVER RIGID FOAM INSULATION SHEATHING vary the actual presence or location of the vapor retarder. 1/2" gypsum wallboard Vapor retarder Insulating Panel Roofs Batt insulation Insulating APA panel roof decks is sim- Wood studs (2x4 with R11 or R15HD insula- pler, quicker and less expensive than tion or 2x6 with R19 or R21HD insulation) other decks since batt insulation can be Rigid foam insulation (R4 min.) applied on the underside of the deck APA RATED SIDING (11/32" or thicker) when ventilation is provided – and roofing on top – without further prepa- R ration. Most metal roof systems, on the Outside surface (15 mph wind) 0.17 Insulation Minimum other hand, require special rigid insula- APA RATED SIDING 0.43–0.78 Option Average U Effective R = 1/U tion on top of the deck to provide the Rigid foam insulation 4.00 (min.) Batt insulation E 0.070 14.37 smooth surface needed for roofing. The Option A – R11 11.00 F 0.061 16.42 Option B – R15HD (high density) 15.00 G 0.050 19.87 panel deck with blanket insulation also Option C – R19 18.00(a) Option D – R21HD (high density) 21.00 H 0.047 21.44 provides better sound absorption, an 1/2" gypsum wallboard 0.45 important consideration in commercial, Inside surface (still air) 0.68 industrial and institutional construction. (a) When compressed to 5-1/2" thickness. (b) Average U values include adjustment for 25% framing area with studs spaced 16" o.c. When studs are spaced 24" o.c. (22% framing area), average U values are slightly lower and corresponding R values are higher. Average U value is based on R value at framing of 4.38 for 2x4 wood studs and 6.88 for 2x6 wood studs.

67 BUILDING REQUIREMENTS AND RELATED PANEL SYSTEMS

A wood frame-panel roof deck system can be effectively insulated through a FIGURE 37 variety of techniques. Figure 37 shows AVERAGE "U" VALUES OF APA PANEL ROOF DECKS four APA panel roof decks – three with No Insulation Roofing Reflective Insulation(a) insulation and one without. Average U Outside surface values for below-deck insulation include Inside surface Ventilated air space adjustment for 8 percent framing area. Air space APA panel Condensation: roof deck Winter Summer No. of equal air spaces Winter Summer 0.578 0.472 1 0.254 0.100 Its Cause and Control 2 0.183 0.075 3 Today’s construction techniques usually 0.117 0.066 (a) Foil sheets assumed reflective both sides produce a far better sealed and insulated except exposed bottom.

building than those built in the past. At Rigid Insulation Batt Insulation the same time, the modern house is likely to be equipped with appliances Ventilated air space that give off moisture. It is more Rigid insulation important than ever before, therefore, board Winter Summer Winter Summer to provide adequate measures for 0.222 0.204 R11(b) Fiberboard/ 1 in. 0.082 0.079 perlite board 1-1/2 in. 0.169 0.159 controlling moisture and condensation. 0.143 0.136 2 in. (b) Min. 2x6 joists required to provide Lack of attention to this area may cause air space. Composite 1-1/2 in. 0.119 0.114 difficulties and costly callbacks. board 2 in. 0.085 0.083 Studies show that moisture originates Polyurethane 1 in. 0.099 0.096 board 1-1/2 in. 0.070 0.068 both inside and outside the structure. Trouble may start with condensation on the underside of roof decking in the space, the crawl space ventilation ratio spaces. In cold climates, low temper- attic. Moisture transmission through may be reduced to 1 to 1500. The ratio atures beneath the first floor may be walls can cause paint failures on exterior in the attic area may be reduced to 1 to expected in a ventilated crawl space, walls. The solution is adequate ventila- 300 provided: 1) a vapor retarder having and insulation will be required in the tion and properly placed moisture vapor a transmission rate not exceeding 1 floor and around exposed mechanical retarders. The latter should always be perm is installed on the warm side of lines. When a vapor retarder is installed located on or near the warm side of the ceiling, or 2) at least 50 percent of for ground cover, vents may be closable walls and floors. Ceiling vapor retarders the required ventilating area is provided and the perimeter foundation wall may are typically omitted where attics are by ventilators located in the upper por- be insulated in lieu of the floor. well ventilated. tion of the space to be ventilated, with Moisture control recommendations for Minimum ventilation requirements for the balance of the required ventilation low slope APA panel roof decks are both attic and crawl space appear in the provided by eave or cornice vents. described in Engineered Wood Systems CABO One and Two Family Dwelling In general, condensation can be con- (EWS) Technical Note, Moisture Control Code, the International Residential trolled with a vapor retarder placed on in Low Slope Roofs, Form EWS R525, Code, and in other model building the warm side of the walls and below available from APA. codes. The requirements are based on concrete slabs or as a ground cover in Additional information is available in the ratio of the free ventilation area to crawl spaces, along with adequate venti- Engineered Wood Systems (EWS) the area to be ventilated. The required lation in attics and crawl spaces. Technical Note, Controlling Decay in ratio is 1 to 150, applicable to both Ventilation should not be cut off at any Wood Construction, Form EWS R495. crawl spaces and attic areas. When a time during the year when it is the only ground cover is placed in the crawl means of moisture control in crawl

68 Thermal Resistance of RELATED use hot-dipped or hot-tumbled galva- Wood Structural Panels PANEL SYSTEMS nized nails. If the underside of the joists For most wood structural panel is covered, the floor-ceiling cavity applications, the most important thermal The Permanent Wood Foundation should be vented to aid in drying and quality is resistance, or insulating effec- The Permanent Wood Foundation to prevent potential moisture buildup tiveness. While wood structural panels (PWF), also referred to as the All- in the deck. include plywood, OSB and COM-PLY Weather Wood Foundation (AWWF), is If there is a dry living area underneath and can be made up of a number of made up of pressure-preservative-treated the deck, apply a membrane roof different species, the thermal resistance below-grade stud walls built of lumber covering or high performance coating property is relatively insensitive to such and APA trademarked plywood. The over the surface. The coating should differences. For determining the overall system is accepted for FHA mortgage be able to accommodate normal dimen- coefficient of heat transmission (U), as insurance programs. It’s accepted by the sional changes in the plywood without illustrated above, APA publications rely major model building codes and most rupturing or cracking. Under these on the thermal resistance values for state and local codes. And, whether full conditions, APA RATED STURD-I- softwood published by the American basement or crawl space, the PWF is FLOOR Exposure 1 may be used unless Society of Heating, Refrigeration and Air adaptable to almost any site and light- otherwise recommended by the coating Conditioning Engineers (ASHRAE). Use frame building design. manufacturer, and preservative treat- of this single value simplifies computa- For complete design and construction ment of the panels is not necessary. tions and produces only insignificant recommendations, contact the American differences in resulting design heat Plywood for Concrete Forming Forest & Paper Association, 1111 19th losses. Table 36 shows thermal resis- Plywood is an ideal material for concrete Street, NW, Suite 800, Washington, DC tance, R, for several panel thicknesses. forming. It produces smooth concrete 20036; or the Southern Pine Marketing surfaces and can be used repeatedly – Council, P.O. Box 641700, Kenner, some overlaid panels up to 200 times or Louisiana, 70064. TABLE 36 more. The thinner panels can be bent THERMAL RESISTANCE Plywood for Outdoor Decks easily for curved forms and liners. Panel Thermal Plywood’s excellent stiffness minimizes Thickness (in.) Resistance, R(a) Exterior-type plywood may be used in outdoor deck applications. Recom- deflection during pouring. Its natural 1/4 0.31 mended grades include APA RATED insulating qualities help provide more 5/16 0.39 STURD-I-FLOOR Exterior, C-C consistent curing conditions. The large 3/8 0.47 Plugged, Underlayment C-C Plugged, panel size and light weight reduce form or Marine. Where the deck may be construction and stripping time. And 7/16 0.55 exposed to long-term dampness, such various surface textures are available 15/32 0.59 as applications where the plywood is for imparting attractive and unusual 1/2 0.62 topped with outdoor carpet, the ply- concrete textures. wood should be pressure-treated with a 19/32 0.74 Although nearly any Exterior plywood waterborne ACA or CCA preservative in can be used for concrete forming, a 5/8 0.78 accordance with AWPA Standard C9 for special panel called PLYFORM® Class I 23/32 0.90 above-ground exposure. For optimum is manufactured specifically for the performance, slope the deck away from purpose. PLYFORM also can be manu- 3/4 0.94 the structure. A slope of 1/4 to 1/2 inch factured with a High Density Overlay 7/8 1.09 is suggested. (HDO) surface, and in Structural I 1 1.25 Space panels 1/8 inch at ends and edges panels. HDO PLYFORM has an to allow for expansion. Caulk the joints exceptionally hard surface for the 1-1/8 1.41 to prevent water leakage into areas smoothest possible concrete finishes

(a) Degree F-hr.-sq.ft./BTU underneath. To avoid fastener corrosion, and maximum number of pours.

69 BUILDING REQUIREMENTS AND RELATED PANEL SYSTEMS

Structural I PLYFORM is stronger and APA Panels Over Metal Framing adhesives. Since threads usually stiffer than PLYFORM Class I, particu- Modern fastening methods are rapidly extend only part way up the shank of larly in the cross-panel direction, and is expanding the use of APA panels over self-, self-tapping screws and sometimes used for high pressures metal framing. Self-drilling, self-tapping screw-shank nails, it is important to where long dimension is parallel to fasteners commonly are used to attach specify a length sufficient to engage the supports. Additional plywood grades panels up to 1-1/8 inch thick to steel metal framing. designed for concrete forming include flanges. Panels also can be fastened to Typical panel-to-metal framing systems special overlays and proprietary panels. lighter members, such as formed steel are illustrated in Figure 38. Load-span For complete design information, write joists, with special hardened screw- recommendations are the same as for APA’s Design/Construction Guide: shank nails. Construction adhesives are for wood-frame systems. For more Concrete Forming, Form V345. recommended with hardened screw- information, write for APA Design/ shank nails. Consult metal framing Construction Guide: Wood Structural Structural Insulated Panels manufacturers for recommended Panels Over Metal Framing, Form T625. The structural insulated panel, or sand- wich panel, offers the stiffness and load handling capability of a stressed-skin panel, plus light weight, high insulation FIGURE 38 values for relatively small thicknesses, TYPICAL PANEL-TO-METAL FRAMING SYSTEMS and fast panelized construction. Panels Panels Nailed to Nailable Steel Joists are prefabricated by sandwiching an insulating core material such as poly- Hardened screwshank nails required styrene or polyurethane foam, or a APA panel deck paper honeycomb, between wood struc- tural panel “skins.” A structural bond is 2x4 nailer formed between the core and the skins APA panel deck Nail to joist with full structural glues or, in the case Nailable steel joist of some foam materials, by direct Nailable steel joist adhesion of foam to the skins.

With APA panel siding for the outside Nailer Anchored Panels Attached skin, structural insulated panels make with Power Driven Fasteners Directly to Formed Steel Joist attractive, energy-conserving walls on APA panel deck APA panel deck both residential and commercial build- ings. A typical structural insulated floor 2x4 nailer panel might have 19/32-inch top skin Adhesive (optional)

and 3/8-inch bottom skin. Check local Drive pins (size Hardened screw- building requirements relating to ther- and spacing as shank nail or self- tapping fastener mal barrier protection of plastic foam. required) For additional information, write for Metal joist Steel wide (“C” or box Design and Fabrication of Plywood flange beam section) Sandwich Panels, Form U814.

70 ROOF CONSTRUCTION

APA Panel Systems ADDITIONAL Always insist on panels bearing the mark Over Concrete Slabs INFORMATION of quality – the APA trademark. Your APA A system of APA panels over panel purchase is not only your highest sleepers embedded in mastic has About APA – The Engineered possible assurance of product quality, but an been successfully installed over Wood Association and Engineered investment in the many trade services that Wood Systems concrete slabs. Tongue-and-groove APA provides on your behalf. panels eliminate blocking between APA – The Engineered Wood Association is The APA EWS trademark appears only on sleepers at panel edges and allow a nonprofit trade association whose member engineered wood products manufactured by air circulation beneath the floor. mills produce approximately 75 percent of members of Engineered Wood Systems, a Use only panels marked Exterior the structural wood panel products manu- related corporation of APA. The mark or Exposure 1. A vapor barrier is factured in North America. signifies that the manufacturer is committed essential directly above or below The Association’s trademark appears only to a rigorous program of quality verification the slab. Preservative treatment of on products manufactured by member mills and testing and that products are manufac- the sleepers is recommended when and is the manufacturer’s assurance that tured in conformance with an APA or the slab is on or below grade, the product conforms to the standard shown national standard such as ANSI Standard although panels normally will not on the trademark. That standard may be an A190.1, American National Standard for require treatment. APA performance standard, the Voluntary Structural Glued Laminated Timber. Tongue-and-groove plywood can be Product Standard PS 1-95 for Construction For additional information on wood installed over polystyrene or and Industrial Plywood or Voluntary construction systems, contact APA – The polyurethane foam. The foam, Product Standard PS 2-92, Performance Engineered Wood Association, P.O. Box bonded to both the plywood and Standards for Wood-Based Structural-Use 11700, Tacoma, Washington 98411-0700, concrete slab with mastic, provides Panels. Panel quality of all APA or the nearest APA regional field office high insulating value and resistance trademarked products is subject to listed on the back cover. Visit us on the to termites, rot and fungus. verification through APA audit. World Wide Web at www.apawood.org. For Exterior plywood at least 15/32 APA’s services go far beyond quality testing a list of additional APA and Engineered inch thick is recommended. A and inspection. Research and promotion Wood Systems publications, request the: vapor barrier such as polyethylene programs play important roles in developing APA Publications Index, Form B300 is required either directly above or and improving plywood and other panel EWS Publications Index, Form S400 below the concrete slab. construction systems, and in helping users and specifiers to better understand and Special Floor Surfacing apply panel products. Hardboard overlaid plywood (APA PLYRON®) is sometimes used as a finish floor, especially for industrial installation. (Check your local dealer for availability.) High Density Overlay (HDO) panels with a spe- cial heavy-duty screen-grid surface provide skid-resistant, long-wearing surfaces under foot traffic. And a number of liquid coatings – some suitable for balconies, porches, patio decks and other exterior applications – are also available.

71 ENGINEERED WOOD CONSTRUCTION GUIDE We have field representatives in most major U.S. cities and in Canada who can help answer questions involving APA trademarked products. For additional assistance in specifying APA engineered wood products, contact us:

APA – THE ENGINEERED WOOD ASSOCIATION HEADQUARTERS 7011 So. 19th St. P.O. Box 11700 Tacoma, Washington 98411-0700 (253) 565-6600 Fax: (253) 565-7265

Addre eb ss W@ : www.apawood.org

PRODUCT SUPPORT HELP DESK (253) 620-7400 E-mail Address: [email protected]

(Offices: Bournemouth, United Kingdom; Hamburg, Germany; Mexico City, Mexico; Tokyo, Japan.)

The product use recommendations in this publica- tion are based on APA – The Engineered Wood Association’s continuing programs of laboratory testing, product research, and comprehensive field experience. However, because the Association has no control over quality of workmanship or the con- ditions under which engineered wood products are used, it cannot accept responsibility for product performance or designs as actually constructed. Because engineered wood product performance requirements vary geographically, consult your local architect, engineer or design professional to assure compliance with code, construction, and performance requirements.

Form No. E30R/Revised January 2001/0800

APA THE ENGINEERED WOOD ASSOCIATION

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