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APA Panel Glossary Handbook

APA Panel Glossary Handbook

GDE,X505,PH&GG.0 4/17/00 3:51 PM Page 1

APA The Engineered Association

GLOSSARY

PANEL HANDBOOK & GRADE GLOSSARY GDE,X505,PH&GG.0 4/17/00 3:51 PM Page 2

APA The Association

DO THE RIGHT THING RIGHT™

Wood is good. It is the earth’s natural, energy efficient and renewable . Engineered wood is a better use of wood. It uses less wood to make more wood products. ORIZED BY APA IS PROHIBITED BY THE U.S. COPYRIGHT LAWS. THE U.S. IS PROHIBITED BY APA ORIZED BY That’s why using APA trademarked , and APA EWS glued laminated timbers is the right thing to do.

A few facts about wood. We’re not running out of . One-third of the United States land base – 731 million acres – is covered by . 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 . Most of that harvestable acreage also is open to other uses, such as camping, hiking, hunting, etc.

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 products , 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.

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

Good 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. Wood. It’s the right product for the environment.

NOTICE: • ALL RIGHTS RESERVED. • ANY COPYING, MODIFICATION, DISTRIBUTION OR OTHER USE OF THIS PUBLICATION OTHER THAN AS EXPRESSLY AUTH THAN AS EXPRESSLY OTHER USE OF THIS PUBLICATION DISTRIBUTION OR OTHER MODIFICATION, • ANY COPYING, • ALL RIGHTS RESERVED. The recommendations in this guide apply only to panels that bear the APA APA trademark. Only panels THE ENGINEERED WOOD ASSOCIATION bearing the APA trademark are subject to the Association’s quality RATED SHEATHING15/32 INCH 32/16 auditing program. SIZED FOR SPACING EXPOSURE 1 000 PS 1-95 C-D PRP-108 APA – THE ENGINEERED WOOD ASSOCIATION APA ©1997 GDE,X505,PH&GG.0 4/17/00 3:51 PM Page 3

his glossary from APA – The Engineered Wood Association is designed as a T handy reference guide to wood structural panel products and common con- struction terminology. It contains up-to-date information about APA Performance Rated Panels, plywood , sanded grades, panel systems, grading terminology, fasteners, finishing, and much more.

For more detailed information about APA panel products and construction sys- tems, write for a free copy of the Publications Index, Form B300, P.O. Box 11700, Tacoma, Washington 98411-0700.

The Association maintains a comprehensive inventory of publications for archi- tects, builders, dealers, do-it-yourselfers and others who use and specify wood structural panel products. GDE,X505,PH&GG.0 4/17/00 3:51 PM Page 4

A A-C Exterior AFG-01 A sanded plywood panel with A-grade A performance specification developed A-A face, C-grade back and C-grade inner by APA – The Engineered Wood plies. Bonded with exterior glue. Association for glues recommended for A sanded plywood panel with A-grade Commonly used for soffits, fences, use in the APA Glued System. face and back plies and D-grade inner boxcar and truck linings, farm buildings, AFG-01 requires that glues applied at plies. Bonded with interior or exterior tanks, commercial the job site be sunlight resistant, strong glue. Commonly used for cabinets, refrigerators and other under many moisture and temperature built-ins, , partitions and other APA high-moisture applica- THE ENGINEERED conditions, and able to fill gaps. interior or protected applications where WOOD ASSOCIATION tions where the a smooth surface or appearance quality Aggregate-Coated Panel appearance or A-C GROUP 1 on both sides is important. A panel coated with stone chips smoothness of only EXTERIOR A-A • G-1 • EXPOSURE 1-APA • 000 • PS1-95 000 imbedded in a coating. one side is important. PS 1-95

A-A Exterior Air-Dried A sanded plywood panel with A-grade Acrylic Resin See SEASONING. face and back plies and C-grade inner An ingredient of water-base () APA – The Engineered plies. Bonded with exterior glue. and stains. Synthetic resin with Wood Association Commonly used for fences, built-ins, excellent weathering characteristics. The trade organization representing signs, boats, cabinets, commercial refrig- Acrylics can be colorless and transpar- most of the nation’s wood structural erators, shipping containers, tanks, tote ent, or pigmented. panel manufacturers. The Association boxes, ducts and other exterior or high has three main functions: 1) research to moisture applications where a smooth improve plywood and other engineered See GLUE. surface or appearance quality on both wood products and systems, 2) quality sides is important. A-D inspection and testing to assure the A-A • G-1 • EXT-APA • 000 • PS1-95 A sanded plywood panel with A-grade manufacture of high quality panel face, D-grade back and D-grade inner products, and 3) promotion of panel A-B plies. Bonded with interior or exterior products and building systems. A sanded plywood panel with A-grade glue. Commonly used Anchor Bolt face, B-grade back and D-grade inner for paneling, built-ins, Bolts that the and thus the plies. Bonded with interior or exterior shelving, partitions APA THE ENGINEERED frame of a structure to its foundation. glue. Commonly used as a substitute for and other interior or WOOD ASSOCIATION A-A where the appearance of one side is protected applications APA Glued Floor System A-D GROUP 1 less important. where the appearance A floor system developed by APA in EXPOSURE 1 A-B • G-1 • EXPOSURE 1-APA • 000 • PS1-95 or smoothness of only 000 which a single layer of APA RATED PS 1-95 one side is important. STURD-I-FLOOR panels (or subflooring A-B Exterior in the case of double-layer construction) A sanded plywood panel with A-grade is glue-nailed to wood . The bond face, B-grade back and C-grade inner is so strong that floor and joists behave plies. Bonded with exterior glue. like an integral unit, increasing floor Commonly used as a substitute for stiffness and greatly reducing floor A-A Exterior where the appearance of squeaks and popping. Only con- one side is less important. struction conforming to APA specification AFG-01 are recommended A-B • G-1 • EXT-APA • 000 • PS1-95 for use with the system. See T-.

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APA Performance Rated Panels® APA Rated® Siding Panel products developed by APA – The A grade designation covering APA Engineered Wood Association, such as proprietary siding products. Commonly APA RATED SHEATHING, APA RATED used, in addition to siding, for fencing, STURD-I-FLOOR and APA RATED soffits, wind screens and other exterior SIDING, designed and manufactured to applications. Can be used for interior Brushed meet performance criteria for specific paneling. Can be manufactured as end-use applications. APA Performance conventional veneered plywood, as a Rated Panels can be manufactured as composite or as oriented strand board conventional veneered plywood, as siding. Both panel and lap siding are composites (veneer faces bonded to available. Special surface treatment such reconstituted wood cores), or as mat- as V-, channel groove, deep formed panels (including groove (such as APA Texture 1-11), Rough sawn and oriented strand board.) The trade- brushed, rough sawn and texture- marks on APA Performance Rated Panels embossed (MDO). Span Rating (stud include a Span Rating denoting the spacing for siding qualified for APA maximum recommended spacing of Sturd-I-Wall applications) and face grade supports over which the panel should classification (for veneer-faced siding) be placed for the designated end indicated in trademark.

use, and the exposure durability APA Texture One-Eleven® classification of the panel. APA APA THE ENGINEERED THE ENGINEERED APA Rated® Sheathing WOOD ASSOCIATION WOOD ASSOCIATION An APA Performance Rated Panel RATED SIDING RATED SIDING 15/32 INCH 303-18-S/W 24 oc 11/32 INCH designed and manufactured specifically SIZED FOR SPACING 16 oc GROUP 1 EXTERIOR SIZED FOR SPACING EXTERIOR for residential and other light frame wall 000 PRP-108 000 sheathing, roof sheathing and subfloor- PS 1-95 PRP-108 FHA-UM-64 Kerfed ing applications. APA RATED SHEATH- ING can be manufactured with Span Ratings of 12/0, 16/0, 20/0, 24/0, 24/16, 32/16, 40/20 and 48/24, in thick- nesses ranging from APA 5/16 to 3/4 inches, THE ENGINEERED WOOD ASSOCIATION Reverse board & and in three exposure RATED SHEATHING durability classifica- 24/16 7/16 INCH SIZED FOR SPACING tions – Exterior, EXPOSURE 1 000 Exposure 1 and PRP-108 Exposure 2.

Channel groove

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APA Rated Sturd-I-Floor® APA Sturd-I-Wall® An APA Performance Rated Panel A construction system in which APA APA STURD-I-WALL® designed and manufactured specifically Rated Siding panels or lap are attached VERTICAL APPLICATION for residential and other light frame directly to studs (single wall) or over Insulation Rated Siding single-floor (combined subfloor-under- nonstructural wall sheathing, such as as required layment) applications for use under , gypsumboard or rigid foam carpet. APA RATED STURD-I-FLOOR insulation. APA Siding bearing a Span can be manufactured with Span Ratings Rating of 24 oc in the trademark can be of 16, 20, 24, 32 and 48 oc, in thick- applied vertically direct to studs spaced nesses ranging from 19/32 to 24 inches on center. Siding with a Span 1-1/8 inch, and in three exposure dura- Rating of 16 oc can be used vertically bility classifications – Exterior, Expo- direct to studs 16 inches on center. sure 1 and Exposure 2. Panels are Panels with either Span Rating can be available with either edges or applied direct to studs 24 inches on tongue-and-groove center with face grain horizontal pro- edges as specified. APA vided horizontal joints are blocked. THE ENGINEERED APA RATED STURD-I- WOOD ASSOCIATION

FLOOR 48 oc ply- RATED STURD-I-FLOOR 24 oc 23/32 INCH HORIZONTAL APPLICATION wood, commonly SIZED FOR SPACING T&G NET WIDTH 47-1/2 called 2-4-1, is also EXPOSURE 1 Building 000 behind vertical joints of used in heavy timber PS 1-95 UNDERLAYMENT grooved panel siding PRP-108 Insulation roof construction. as required

Blocking at horizontal joints APA STURD-I-FLOOR®

Carpet STURD-I-FLOOR 16, 20, 24, 32, or 48 oc

Rated ...... Strength axis Vertical Siding ...... at panel butt joints ......

APA Trademark APA – The Engineered Wood Association is an approved quality supervision and testing agency for plywood and wood structural panels. Typical trademarks of APA member-manufac- edges or tured products are shown throughout blocking between supports this brochure. See QUALITY INSPECTION AND TESTING.

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B B-B B-C Exterior A sanded plywood panel with B-grade A plywood panel with sanded B-grade Back-Out face and back and D-grade inner plies. face, C-grade back and C-grade inner Bonded with interior or exterior glue. plies. Bonded with exterior glue. Utility See NAIL POPPING. Utility panel for interior or panel for farm service Back-Priming protected applications. and work buildings, APA Application of a coat of primer to the boxcar and truck THE ENGINEERED B-B • G-2 • EXPOSURE 1-APA • 000 • PS1-95 WOOD ASSOCIATION back of a panel. Cabinet should linings, containers,

be back-primed to prevent warping. B-B Exterior tanks, agricultural B-C GROUP 2 A sanded plywood panel with B-grade equipment, as a EXTERIOR Backstamp 000 face and back and C-grade inner plies. base for exterior PS 1-95 The approved agency mark on the back Bonded with exterior glue. Utility panel coatings, etc. of a panel. All unsanded and touch- with solid paintable surface both sides. sanded panels, and B-D panels with A or B B-B • G-2 • EXT-APA • 000 • PS1-95 A plywood panel with sanded B-grade faces on one side only, APA face, D-grade back and D-grade inner THE ENGINEERED WOOD ASSOCIATION ® carry the APA trade- B-B Plyform plies. Bonded with mark on the panel Concrete form grades with high interior or exterior A-C GROUP 1 APA back. See also reuse factor. Sanded both sides and mill- glue. Utility panel for THE ENGINEERED EXTERIOR WOOD ASSOCIATION APA TRADEMARK 000 oiled unless otherwise specified. Special backing, sides of built- PS 1-95 and EDGEMARK. restrictions on species. Also available in ins, industry shelving, B-D GROUP 2 HDO for very smooth concrete finish, slip sheets, separator EXPOSURE 1 Batten 000 in STRUCTURAL I (all boards, bins, etc. PS 1-95 A thin, narrow strip of plywood or plies limited to Group used to conceal or protect a I species), and with APA THE ENGINEERED joint between adjoining pieces of special overlays. WOOD ASSOCIATION lumber or plywood. EXPOSURE PLYFORM To cut panel edges or ends at an angle B-B CLASS 1 to make smooth mating joints DURABILITY EXTERIOR CLASSIFICATION: 000 between panels. BATTEN PS 1-95 Insulation Exterior. as required

Bevel joint

Batten Rated Siding

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Blocking Box Beam Bundle Light lumber strips nailed between major A beam built of lumber and wood A unit or stack of wood panels held members to support edges of structural panels in the form of a long together for shipment with bands. Stack structural panels where they meet. hollow box which will support more size varies throughout the industry, with load across an opening than will its the average stack running about 30 to Full depth bridging individual members alone. Lumber 33 inches high. A bundle 30 inches acts as blocking members form the top and bottom high, for example, contains 120 sheets (flanges) of the beam, while the sides of 1/4-inch panels, 80 sheets of 3/8-inch (webs) are panels. panels, or 60 sheets of 1/2-inch panels.

BOX BEAM The joint formed when two parts are Lumber flanges fastened together without overlapping. For end-to-end joints, use a nailing Blocking strip. For corner joints, nail directly into Panel webs Bridging both sides panel if it is at least 3/4-inch thick. If panel is thinner than 3/4 inch, use a Lumber reinforcing block. Blow stiffeners A localized delamination caused by

steam pressure buildup during the hot BUTT JOINT pressing operation. The steam may Bridging Short wood or metal braces or struts result from high moisture content of the CORNER JOINT placed crosswise between joists to help veneer, excessive glue spread, or high Nails into press temperatures. keep them in alignment. Bridging may reinforcing be solid or crossed struts. Most building block Boat Patch codes no longer require bridging of See REPAIRS. floor joists. See illustration under BLOCKING. Bond Reinforcing To glue together, as veneers are Brushed blocks “bonded” to form a sheet of plywood. An APA 303 Siding surface treatment. Pressure is applied to keep mating parts Brushed or relief-grain surfaces accent in proper alignment. Most glues used in the natural grain pattern to create strik- panel manufacture require both heat ing textures. Difficult to or stain. and pressure to cure properly. See APA RATED SIDING.

Bow Distortion of a wood structural panel so END-TO-END JOINT that it is not flat lengthwise. See also CUP. Nails Nail strip BOW

Butt joint

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C Clear Span The flat surface created by slicing off the Distance between inside faces Caulk square edge or corner of a piece of of supports. wood or panel. Waterproof sealant used to fill joints or seams. Caulks are available as putties, CLEAR SPAN ropes, or compounds extruded CHAMFER 16" center-to-center from cartridges. mitered C-C Plugged Exterior A touch-sanded plywood panel with Framing C-Plugged-grade face, C-grade back and 14-1/2" clear span inner plies. Bonded with exterior glue. Commonly used for severe moisture condi- Chamfer Code tions, exterior bal- APA See MODEL CODE. THE ENGINEERED conies and decks, WOOD ASSOCIATION Channel Groove COM-PLY® refrigerated or con- C-C PLUGGED An APA 303 Siding texture consisting trolled atmosphere GROUP 1 APA – The Engineered Wood Association EXTERIOR of shallow grooves cut into panel faces proprietary trade name for APA rooms, and boxcar 000 PS 1-95 during manufacture. See APA and truck . member-produced composite panels. RATED SIDING. See APA PERFORMANCE RATED C-D Plugged PANELS and COMPOSITE PANEL. Checking A touch-sanded plywood panel with Wood exposed to alternating moist and C-Plugged-grade face, Component dry conditions eventually develops open D-grade back and A glued and/or nailed structural assem- APA cracks or “checks.” Reduce checking by bly of wood structural panels and lum- inner plies. Bonded THE ENGINEERED WOOD ASSOCIATION sealing panel edges before installation to with interior or exte- ber, such as a stressed-skin panel. Also C-D PLUGGED minimize moisture absorption, and by describes prefabricated building rior glue. Used for GROUP 2 using a priming coat or resin sealer on sections in panelized construction. built-ins, cable reels EXPOSURE 1 000 the surfaces. and walkways. PS 1-95 Composite Panel Chord A veneer-faced panel with a reconstituted Center (Centers) Any of the outside members of a wood core. See APA PERFORMANCE connected by web members. Also, may Inner ply or plies of a plywood panel RATED PANELS and COM-PLY. refer to perimeter members of a panel whose grain runs parallel with that of diaphragm. See illustration under TRUSS. @@@@@@€€€€€€ÀÀÀÀÀÀ the face and back plies. COMPOSITE PANEL

Circular Plug @@@@@@€€€€€€ÀÀÀÀÀÀ Center Gap See REPAIRS.

See CORE GAP. @@@@@@€€€€€€ÀÀÀÀÀÀ Class I Center-To-Center See B-B PLYFORM. @@@@@@€€€€€€ÀÀÀÀÀÀ See ON-CENTER and CLEAR SPAN.

@@@@@@€€€€€€ÀÀÀÀÀÀ

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Concentrated Load Core Gap (Center Gap) Cross Cutting See LOADS. An open veneer joint extending Sawing wood across the grain. Because through, or partially through, a plywood the wood in wood structural panels is Concrete Form panel. Product Standard PS 1 specifies either cross-laminated or randomly Mold into which fresh concrete is that the average of all gaps shall not oriented, any cut made in a wood struc- placed to set. Plywood provides tough, exceed 1/2 inch, and that every effort tural panel is a cross cut. Always use a durable, easy-to-handle, split-resistant be made to produce closely butted cross-cut when hand- or power- and lightweight concrete forms. It can core joints. sawing wood structural panels. be bent for curved forms and liners, and its natural insulating properties help Crawl Space Cup moderate temperature variations for A space often about two feet high Crosswise distortion of a wood more consistent curing. Almost any APA beneath a floor allowing access to structural panel from its flat . trademarked plywood can be used in plumbing or wiring. See also PIRF. See also BOW. concrete applications, but PLYFORM is specifically manufactured Cripple CUP for that purpose. See also B-B Any vertical framing member cut less PLYFORM. than full length, as in cripple studs Distortion under a window opening. across panel Core (Cores) In conventional plywood, inner plies Crossband (Cores) whose grain runs perpendicular to that In plywood, the veneer layers with grain of the outer plies. In composite panels, direction perpendicular to that of the a layer of reconstituted wood. face plies. See CORE. See also PLY. Curved Panel Stressed-skin or sandwich panels curved

CORE to various degrees of arc. Used in roof construction. 3-PLY PANEL

CURVED PANEL

Plywood upper skin

Insulation

Core Plywood lower skin

Plywood or lumber ribs

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D DIAPHRAGM Roof (horizontal diaphragm) carries load to end walls. Joint Joint formed by intersection of two boards, one of which is notched with a rectangular groove.

DADO JOINT

Wind load Side wall (vertical diaphragm) carries load to roof End wall (vertical diaphragm at top and to diaphragm) carries foundation at bottom. load to foundation.

Diaphragm Double Wall Elements of a building that provide A light frame wall construction system consisting of exterior finish siding, such Dead Load (D.L.) shear strength to withstand wind and as APA RATED SIDING, applied over See LOADS. earthquake loads. structural wall sheathing – typically Decorative Panel Dogbone Plug APA RATED SHEATHING. See A plywood panel grade with rough- See REPAIRS. APA STURD-I-WALL. sawn, brushed, grooved or striated faces. May be any exposure durability. Common uses include paneling, built- DOUBLE WALL ins, accent walls, counter facings and SIDING OVER APA RATED SHEATHING displays. Exterior uses include siding, gable ends and fences. Check with manufac- APA turer for specific THE ENGINEERED WOOD ASSOCIATION Exterior application DECORATIVE recommendations, GROUP 2 which vary with par- EXPOSURE 1 000 ticular products. PS 1-95

Deflection Bending of a wood structural panel or framing member between supports under an applied load.

Delamination Separation between plies or within reconstituted wood due to adhesive

bond failure. Separation in area immedi- Sheathing ately over or around a permitted defect (applied horizontally) does not constitute delamination. Sheathing Rated Siding (applied vertically)

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E Edge Treatment End Spacing Edge finishing method, such as banding See PANEL SPACING. Eave with wood or plastic, or filling with putty or spackle. Engineered 24" Framing The edge of a roof that extends beyond A building system using wood structural or overhangs a wall. The underside of an panels over lumber framing spaced EDGE TREATMENTS eave may form an “open soffit.” Textured 24 inches on center in walls, floors panels, applied face down to eave and roof. The system’s series of in-line as roof sheathing, give open soffits a frames – , studs and joists – decorative finished surface. See SOFFIT. provide cost-effective materials utiliza- Butt edging. Keep edges square; Edgemark use matching strip of . tion and simpler, faster construction. It is recognized by major model APA trademark stamped on the panel codes and the FHA. edge. Appears on sanded grades with B-grade or better veneer faces, PLYRON, Expansion MARINE, and panels with overlaid Butt edging. Keep edges square; Moisture absorption causes wood to surfaces on both sides. use matching strip of solid wood. expand. Spacing between panel edges A-B • G-1 • EXT-APA • 000 • PS1-95 and ends is recommended to allow for any possible panel swelling. See Edge Sealing PANEL SPACING.

Application of a coating (e.g., sealant, “Mitered” butt edging. Use glue paint) to the edges of a wood structural and brads to fasten strips. Exposure Durability Classification panel to reduce its water absorption. Exposure ratings for APA wood Edge seal before painting the panel structural panels designated in APA Edge Void surface if panel edges will be exposed trademarks as Exterior, Exposure 1, A panel defect in which the edge or end to repeated wetting and drying. Exposure 2, or Interior. of an inner ply has split or broken away Exterior panels have a fully waterproof during manufacture, leaving a gap in the Edge Spacing bond and are designed for applications edge of the plywood panel. See PANEL SPACING. subject to permanent exposure to the Edge Support Embossed weather or to moisture. Support, such as panel clips or lumber A panel surface treatment. Heat and Exposure 1 panels have a fully water- blocking, installed between framing pressure against a master pattern proof bond and are designed for appli- members at wood structural panel edges impress a variety of textured effects cations where long construction delays to transfer loads from one panel to the into panel surfaces, which remain may be expected prior to providing other across the joint. Panels with smooth and paintable. protection, or where high moisture tongue-and-groove edges can be used in conditions may be encountered in End Grain many applications without additional service. Exposure 1 panels are made The end of a piece of wood exposed edge support. with the same exterior adhesives used in when the wood are cut across Exterior panels. However, because other the grain. All wood structural panel compositional factors may affect bond edges are end grain, and should be performance, only Exterior panels finished accordingly. should be used for permanent exposure to the weather.

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Exposure 2 panels (identified as F Fascia Interior with intermediate glue under Wood or plywood trim used along the PS 1) are intended for protected con- Face eave or the gable end of a structure. struction applications where only mod- The highest-grade side of any veneer- erate delays in providing protection faced panel that has outer plies of differ- from moisture may be expected. ent veneer grades. Also, either side of a Interior panels or panels which lack panel where grading rules draw no further glueline information in their distinction between faces. For example, trademarks are manufactured with inte- the face of an A-C panel is the side with rior glue and are intended for interior the A-grade outer ply. Both sides of an applications only. A-A or B-B panel are referred to as faces.

Exposure 1 Face-Checking See EXPOSURE DURABILITY Partial separation of wood fibers parallel Fascia CLASSIFICATION. to grain in the wood or veneer surfaces of panels caused chiefly by the strains Exposure 2 of weathering and seasoning. See EXPOSURE DURABILITY See CHECKING. CLASSIFICATION. Fiberglass-Reinforced Plastic (FRP) Face Grain A tough, nonscuff plywood coating Exterior Direction of the grain of the outer ply made of glass fibers combined with PS 1 exposure durability term for (face) of a veneer-faced panel in relation . These coated panels (composite) plywood manufactured for permanent to its supports. A panel’s greatest stiff- are used in truck and trailer bodies, outdoor or marine use and bonded with ness and strength is parallel to the face containers and concrete forms. Seamless 100 percent waterproof adhesives. grain. Therefore, in construction, run panels 40 feet long and longer can be See INTERIOR and EXPOSURE the face grain or long dimension of the produced as trailer sidewalls or roofs. DURABILITY CLASSIFICATION. panel across supports for greatest stiff- Filler Exterior Glue ness and strength. A material for filling nail holes, checks, A 100 percent waterproof adhesive cracks or other blemishes in surfaces bonding all Exterior, Exposure 1 and of wood before application of paint, most Interior panels. For applications or other finishes. subject to temporary exposure to mois- ture during construction, specify Exposure 1 or Exposure 2. For permanent exposure to weather or moisture, use only Exterior panels. See also INTERIOR GLUE, INTER- MEDIATE GLUE and EXPOSURE DURABILITY CLASSIFICATION.

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Finishes one-hour rating, for example, means Foam Core Stains, paints or sealers which protect, that an assembly similar to that tested Center of a structural wood panel-faced color or enhance the natural beauty of will collapse nor transmit flame “sandwich” panel. Liquid plastic wood structural panels. or high temperature for at least one foamed into all spaces between the Exterior finishes primarily protect hour after a fire starts. Structural wood panels serves to both insulate and sup- siding and maintain its appearance. panels are an approved material in a port the component skins. Or structural They minimize the weathering action number of fire-rated designs. wood panel skins are pressure-glued to which roughens and erodes the surface See FLAME SPREAD. both sides of rigid plastic foam boards or billets. See SANDWICH PANEL. of unfinished wood. Different finishes Fire-Retardant-Treated (FRT) give varying degrees of protection so the Chemical treatment of wood and ply- Footing type, quality, quantity and application wood to retard combustion. Plywood is The base for foundation walls, posts, must be considered to achieve the pressure-impregnated with fire retardant chimneys, etc. The footing is wider than desired performance. All exterior panel chemicals mixed in water in accordance the member it supports, and distributes edges should be sealed if the panels will with American Wood Preservers the weight of the structure to the be painted or stained. Sealing while Association Standard AWPA C27. ground over a larger area to prevent panels are stacked is easiest. Exterior NOTE: Span Ratings and load capacities settling. finishes recommended for wood struc- are based on untreated panels, and may tural panels include semi-transparent not apply following fire-retardant treat- Frame Construction stain, solid-color stain and acrylic ment. Obtain structural performance Construction in which the structural latex paint. characteristics of FRT panels from the parts are wood or dependent on a wood Interior finishes: Preparation is providing the treatment and framework for support. Typically, lumber minimal. Overlaid (MDO and HDO) redrying service. framing is sheathed with wood struc- plywood needs no preparation; sanded tural panels for roofs, walls and floor. and textured grades require only touch- Flame Spread The classification of frame construction sanding. Recommended interior finishes The spread of fire along the surface of remains the same in building codes include oil base paint, latex paint, a material. Flame spread ratings are even when masonry covering is applied stain and sealer. expressed in numbers or letters and on exterior walls. are used in building code interior Fire-Rated Systems finish requirements. FRP Wall, floor and roof construction of See FIBERGLASS-REINFORCED specific materials and designs that has Flange PLASTIC. Top and bottom longitudinal members been tested and rated according to fire FRT safety criteria (e.g., flame spread rate of a beam. Box beams are fabricated See FIRE-RETARDANT-TREATED. and fire resistance). Testing and approval with lumber flanges (top and bottom) are performed by agencies such as and structural wood panel webs (sides). Furring Underwriters Laboratories, Inc. A See BOX BEAM. Process of leveling parts of a ceiling, wall Flashing or floor by means of wood strips, called See Z FLASHING. furring strips, before adding panel cover.

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FRAME CONSTRUCTION Ridge board Outrigger Cripples Plywood or lumber splice Fascia

Collar beam Top plate (doubled) Roof rafter Header Ceiling

Stud walls

Header joist

Bottom plate

Corner (usually 3 posts) Anchor bolts Sill plate

FRAME CONSTRUCTION Partition wall Center bearing wall (non-load bearing) APA panel Outside bearing wall roof sheathing

APA panel subflooring or Fascia APA STURD-I-FLOOR

Floor joists

APA panel wall sheathing or APA Rated Siding

Foundation (concrete block shown) Glulam girder Lumber post Post footing Footing

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G Other available glues include: Hot pieces should meet continuously along melt glues – for relatively small parts. their joint. Apply glue to one or both Remember they cool and set quickly. surfaces according to manufacturer’s Girder Epoxy glues – limited use; most are directions, then press surfaces together A large horizontal beam which supports not formulated for wood. Expensive. and nail in place. For work such as cabi- interior walls or joists. Most wood frame Contact Cements – useful for applying nets or drawers, or whenever possible, have a lengthwise center girder laminates and edge stripping to ply- joint should be clamped as well as nailed that supports the joists and floor panels. wood. Not recommended for structural to maintain pressure until glue sets. See FRAME CONSTRUCTION. joints. Wall panel adhesives – handy Glued Floor System Glue for applying decorative paneling or See APA GLUED FLOOR SYSTEM. Many adhesives, preferably in facing. May require a few nails per panel conjunction with nails or other fasten- to position panels while glue sets. Glueline ers, produce strong joints in structural Casein glues – slow setting, permitting The adhesive joint formed between wood panel construction. Type depends easier construction of difficult veneers in a plywood panel or between on purpose and exposure of finished assemblies. face veneers and core in a composite product. The most common glues are Glue-Nailed (Nail-Glued) panel (primary glueline), or between listed in the chart below. lumber and wood structural panel parts Gluing wood structural panel joints and in an assembly such as a component connections with pressure provided by (secondary glueline). nailing. For most effective fastening,

GLUES Type of Glue Description Recommended Use Precautions How to Use Urea Comes as powder to be Good for general wood Needs well-fitted joints, Make sure joint fits tightly. Resin mixed with water and used gluing. For work that must tight clamping, and room Mix glue and apply thin coat. Glue within 4 hours. Light colored. stand some exposure to temperature 70° or warmer. Allow 16 hours drying time. Very strong if joint fits well. dampness, but is not Some require heat to cure. completely waterproof. Liquid Comes ready to use at any Good for indoor furniture Not sufficiently resistant to Use at any temperature Resin temperature. Clean-working, and cabinetwork. First moisture for outdoor but preferably above 60°. (White) quick-setting. Strong choice for small jobs where furniture or outdoor Spread on both surfaces, Glue enough for most work, tight clamping or good fit storage units. at once. though not quite as tough may be difficult. Sets in 1-1/2 hours. as urea resin glue. Resorcinol Comes as powder plus This is the glue to use with Expense, mixing difficulty Use within 8 hours after (Waterproof) liquid, must be mixed each Exterior-type plywood for and dark color make it mixing. Work at temperature Glue time used. Dark colored, work to be exposed to unsuited to jobs where above 70°. Apply thin coat very strong, completely extreme dampness. Good waterproof glue is not to both surfaces; allow waterproof. for farm buildings, boats. required. Needs good fit, 16 hours drying time. tight clamping.

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Glulam Grade Grooving is available in a variety of Short for glued-laminated structural Refers to the letter-graded quality of widths and spacings on several surface timber – large beams fabricated by veneers used in plywood manufacture (N, textures. See also APA RATED SIDING bonding layers of specially selected A, B, C-Plugged, C and D), or to particu- and TONGUE-AND-GROOVE JOINT. lumber with strong, durable adhesives. lar panels, e.g., A-A, Underlayment, etc. Group Number End and edge permit produc- See also VENEER GRADE. Plywood is manufactured from over tion of longer and wider structural wood 70 species of softwood. These species are members than are normally available. Grain The natural growth pattern in wood. classified according to strength and stiff- Glulam timbers are used with wood The grain runs lengthwise in the ness under manufacturing standard PS 1 structural panels for many types and is strongest in that direction. into Groups 1 through 5. Group 1 of residential and commercial Similarly, grain usually runs the long are the strongest. The group number of a construction. dimension in the face and back veneers particular panel is determined by the of a plywood panel, making it stronger weakest (highest numbered) species used GLULAM in that direction. Wood structural pan- in face and back (except for some thin els should therefore usually be applied panels where strength parallel to face with the long dimension perpendicular grain is unimportant). to or across supports. Growth Ring Grain Raise A tree’s annual cross-sectional growth The condition on the surface of a layer, including springwood and plywood panel resulting from harder or summerwood. denser wood fibers swelling and rising Gusset Plate above softer surrounding wood. A piece of plywood connecting lumber Groove members of a truss or other frame struc- One of the surface treatments frequently ture. Gussets may be applied to one or given to textured siding in which a both sides of the joint. Plywood is used series of narrow, parallel channels are because of its great strength and cut into the surface of the panel. split-resistance.

GUSSET PLATES

Gussets

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H High Density Overlay (HDO) Impact Insulation Class Plywood finished with a resin- Values which rate the capacity of floor impregnated overlay to provide assemblies to control impact noise such extremely smooth hard surfaces that as . FHA requirements (and Wood of the deciduous or broadleaved need no additional finishing and have some local building codes) specify trees – , , ash, walnut – as high resistance to chemicals and abra- minimum acceptable ratings. distinct from the softwood of the conif- sion. The overlay material is bonded to erous or needleleaved trees – , , both sides of the plywood as an integral Impact Noise Rating , hemlock. The term has only a Values for floor assembly impact part of the panel faces. Used for con- general reference to actual wood hard- sound transmission, now replaced crete forms, cabinets, highway signs, ness. Construction and industrial ply- by IIC classification. counter-tops and other punishing wood may use either variety. See applications. See also MEDIUM SOFTWOOD. Inner Plies DENSITY OVERLAY (MDO). All plies of a plywood panel except HDO face and back. See HIGH DENSITY OVERLAY. I INR Header See IMPACT NOISE RATING. A cross member placed between studs or joints to support loads over openings I-Beam Interior Glue for stairways, chimneys, doors, etc. See See I-Joist. A moisture-resistant, but not also FRAME CONSTRUCTION. waterproof, adhesive used in the Identification Index manufacture of some plywood panels. Former term for Span Rating. Heartwood See also EXTERIOR GLUE, INTER- See SPAN RATING. The nonactive core of a tree distinguish- MEDIATE GLUE and EXPOSURE able from the growing sapwood by its IIC DURABILITY CLASSIFICATION. usually darker color and greater resis- See IMPACT INSULATION CLASS. tance to rot and decay. Interior I-Joist PS 1 exposure durability term for Heavy Timber Joist whose cross section resembles plywood manufactured for indoor A building code designation for a partic- the letter “I”. The flanges of an I-joist are use or construction subjected to only ular type of construction with good fire composed of lumber or laminated temporary moisture. See EXTERIOR endurance. Heavy Timber is widely veneer lumber (LVL), and the web is and EXPOSURE DURABILITY recognized as comparable to one-hour composed of plywood or oriented CLASSIFICATION. construction. A panel roof of strand board. 1-1/8-inch tongue-and-grooved ply- Intermediate Glue wood with exterior glue over 4-inch- An adhesive bonding some PS 1 panels wide supports meets the Heavy Timber I-JOIST which has a moisture resistance midway requirements and provides the same fire between interior and exterior glues. performance as nominal 2-inch tongue- Panels bonded with intermediate glue and-groove lumber decking. are comparable with those designated under APA performance standards as Exposure 2. See EXPOSURE DURABILITY CLASSIFICATION.

Web

Flanges

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J L Lay-Up The step in wood structural panel Jointed Core Lap manufacture in which veneers or reconstituted wood layers are “stacked” Core veneer that has had edges To position adjacent objects so that in complete panel “press loads” after machined square. Gaps between pieces one surface extends over the other. Term gluing and before pressing. Also the of core shall not exceed 3/8 inch, and may designate a lap siding technique, construction of the panel. the average of all gaps in the panel in which each panel or piece overlaps shall not exceed 3/16 inch. the edge of the next lower panel. A Live Loads (L.L.) joint unites two panels when See LOADS. Joist half the thickness of each is cut away Horizontal framing member of a floor, so that the two pieces fit together Loads ceiling or flat roof. Wood structural with outer faces flush. The weight or pressure a structure panels are commonly used for subfloor- carries or sustains, which must be con- ing and underlayment or single-layer sidered in planning a building. Uniform (APA RATED STURD-I-FLOOR) LAP loads are evenly distributed over a large HORIZONTAL JOINTS over floor joists. APA RATED SHEATH- area, usually the entire surface of a panel. ING is typically used over roof joists. Concentrated loads are applied over a very small area (for example, by a leg). Dead loads are stationary, perma- K nent loads; that is, the weight of all the material used in construction of the Kerf building (or section). Live loads are A slot made by a saw; the width planned loads the structure must carry Full lap of a saw cut. under normal conditions, such as people or furniture and equipment, that would Shiplap Kiln-Dried be moved across the structure’s surface. Wood dried in ovens (kilns) by These loads are generally assigned by the controlled heat and to speci- building code for the type of structure; fied limits of moisture content. Veneers for example, a heavy-equipment storage are kiln dried before lay-up. warehouse, a house or an office building. See also SEASONING. Live loads are generally considered to be uniform loads. Knot Natural growth characteristic of wood Lumber Core Layer caused by a branch base imbedded in Plywood manufactured with a core In plywood a layer consists of the tree trunk. composed of lumber strips. The face one or more adjacent plies having and back (outer) plies are veneer. Knothole the in the same direction. Void produced when a knot drops For instance, four ply panels always have out of veneer. three layers with both core plies at right angles to the faces. These two plies are one layer and each face is another. In composite panels, the reconstituted wood portion is one layer and each face is another. See PLY.

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M Model Code Scaffold nails: 8d and 10d most A building code developed by a regional common, for scaffolds, bracing and any temporary fastening that must Marine Grade federation of building officials. These are continually reviewed and updated by later be removed. Plywood panels manufactured with the committees of building officials. Model same glueline durability requirements as codes in the United States are the other Exterior panels but with more Uniform Building Code (UBC), pub- restrictive veneer quality and manufac- lished by the International Conference turing requirements. The grade is partic- of Building Officials; the Standard ularly suitable for marine applications Siding nails: Nonstaining nails of size Building Code (SBC), published by where bending is required, specified for siding thickness. the Southern Building Code Congress as in boat hulls. International; and the National Building MARINE • A-A • EXT-APA • 000 • PS 1-95 Code (NBC), published by the Building Officials and Code Administrators MDO International. Members of these three See MEDIUM DENSITY OVERLAY. Casing and finish nails: 4d, 6d and 8d code organizations comprise the most common, for exterior and interior National Evaluation Service. See Medium Density Overlay trim and installation of siding and NATIONAL EVALUATION SERVICE. Plywood finished with an opaque paneling where large nailheads resin-treated fiber overlay to provide a Moisture Retarder should not show. smooth surface ideal as a paint base. See VAPOR RETARDER. Recommended for siding and other outdoor applications, and for built-ins, Casing signs and displays, furniture, etc. N Available without grooving, with Finishing V-grooves, or in T 1-11 or reverse board-and-batten grooving. See also Nails Roofing nails: A special type, HIGH DENSITY OVERLAY (HDO) Nails commonly used for residential commonly available. Size depends on and APA RATED SIDING. construction include: thickness of roofing and deck material. Common and box nails: 16 penny (d) common and box, for general framing. A joint formed by fitting together two 8d and 10d common and box nails, for pieces of lumber or panels that have . 6d and 8d common and box been cut off at a 45° angle. nails, for subfloor, wall and roof sheath- ing. Size depends on thickness of wood structural panel sheathing. Mitered joint Drywall nails: 4d to 6d size depends on drywall thickness; for 1/2-inch dry- wall use 4d drywall nails. Common

Box

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For underlayment and finish floor: Nail-Glued National Evaluation Service (NES) Special nail types with greater holding See GLUE-NAILED. An arm of the Council of American power than ordinary varieties are also Building Officials sponsored jointly by available. For hardwood strip flooring, Nail Popping the three major American model code Flooring nails occasionally appear to use either 8d hardwood nails or organizations – the International “pop” up so that nail head impressions 2-1/2-inch hardened, spiral-threaded Conference of Building Officials (ICBO); are visible on the surface of the finished (screw-shank) nails. For 1/2-inch and the Southern Building Code Congress floor covering. Shrinkage of floor joist thinner Underlayment grade plywood International (SBCCI); and the Building away from the nail shank after installa- (over subflooring), use 3d ring-shanks. Officials and Code Administrators Inter- tion exposes the head. When floor For 19/32 through 3/4-inch Sturd-I- national (BOCA). NES studies applica- members are dry, make sure fasteners Floor panels, use any of the 4d tions for new products, and publishes are flush with or below floor surface just deformed-shank nails illustrated below. evaluation reports recommending prior to installation of thin floor cover- For 1/4-inch panels use 3/4-inch or approval by its three constituent ing such as tile, linoleum or vinyl. 1-inch brads, 3d finish nails, or (if no members. See MODEL CODE. Fasteners should be set if green framing objection to heads showing) 1-inch blue will present nail popping problems NES nails. For exterior application, use upon drying. Do not fill nail holes. See NATIONAL EVALUATION SERVICE. galvanized or coated nonstaining nails or fasteners. Noise-Rated Systems “Popped” nail Construction designed to reduce sound transmission. Various plywood Screw-shank construction systems tested both in laboratories and buildings meet or Ring-shank exceed requirements.

Nominal Dimension Predrilling is occasionally necessary in Full “designated” dimension. For careful work where nails must be very example, a nominal 2 inch by 4 inch close to panel edges. Select a bit of stud may measure 1-1/2 inch x slightly smaller diameter than the 3-1/2 inch when surfaced. It is a nail to be used. commercial size designation, subject Space nails about 6 inches apart for to acceptable tolerances. See also most work. Closer spacing is necessary SIZED FOR SPACING. only with thin panels which might otherwise buckle slightly between nails. Noncertified Structural panels not included in Product Standard PS 1, or covered under various Performance Standards, and which may bear the mark of the manufacturer rather than a recognized testing agency, such as APA.

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O Oriented Strand Board (OSB) P Wood structural panels manufactured O & ES from reconstituted, mechanically P & TS oriented wood strands bonded with Oiled and edge-sealed. Surfaces of Plugged and touch-sanded face of a resins under heat and pressure. concrete form panels are lightly coated plywood or composite panel. Oriented strand material may be pro- with oil and the edges sealed duced as the center layer of composite if specified. Paints panels, or may be cross-laminated See FINISHES. On-Center (O.C.) in layered panels. See also APA On-center spacing, meaning the PERFORMANCE RATED PANELS. Panel Clip distance from the center of one struc- Specially shaped metal device for sup- Overlaid Plywood tural member to the center of the adja- porting panel edges to reduce differ- Plywood panels with factory-applied, cent member, as in the spacing of ential deflection in roof construction. resin-treated fiber faces on one or both studding, joists, rafters, nails, etc. sides. Term may also apply to metal and See also CLEAR SPAN. PANEL CLIP other overlaid panels. See HIGH DEN- Open Defects SITY OVERLAY (HDO) and MEDIUM Irregularities such as splits, open joints DENSITY OVERLAY (MDO). and knotholes that interrupt the smooth continuity of veneer.

ORIENTED STRAND BOARD (OSB)

Panel Spacing The gap left between installed panels in a structure. Panels in floor, wall or roof deck construction should be spaced to allow for any possible expansion due to changing moisture absorption levels. Proper spacing helps prevent buckling and warping. APA spacing recommendations are:

Panel Type Edge End APA Rated Sheathing 1/8 1/8 APA Rated Siding 1/8 1/8 APA Rated Sturd-I-Floor 1/8 1/8 Underlayment 1/32 1/32

See also SIZED FOR SPACING.

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Paneling Performance Rated Panels® Plugged Core Wood panels joined in a continuous See APA PERFORMANCE Inner ply construction of solid surface, especially decorative panels for RATED PANELS. C-Plugged veneer pieces. Gaps interior wall finish. Textured plywood in between pieces of core should not many varieties is often used as interior Performance Standard exceed 1/2-inch per Product paneling either in full wall sections or A standard applying to panels such as Standard PS 1. See JOINTED CORE. accent walls. See APA RATED SIDING APA RATED SHEATHING, APA RATED for textured plywood used as paneling. STURD-I-FLOOR and APA RATED Plugged Crossbands SIDING. Panels manufactured to meet Under Face (PCUF) Panelized Construction APA performance standards must satisfy A designation denoting a Building components fabricated in wall, rigorous, exacting performance criteria. SANDED PANEL of special floor, or roof sections, etc., to be assem- See also PRODUCT STANDARD and construction, making it suitable bled into a completed structure at the APA PERFORMANCE RATED PANELS. for use as an UNDERLAYMENT, building site. Panelized construction for example A-C (PCUF). speeds erection and cuts on-site labor Permanent Wood Foundation Ply costs. It offers the high quality available See WOOD FOUNDATION. A single veneer in a panel. through controlled factory production PIRF (Perimeter-Insulated and inspection procedures. Raised Floor System) Crawl space foundation-floor system PLIES Patch where insulation is applied only to the See REPAIRS. 3 ply inside of the perimeter foundation stem 3 layer panel PCUF wall. The resulting system saves con- See PLUGGED CROSSBAND struction costs and gives superior UNDER FACE. energy performance.

Peeler Log Streak 4 ply 3 layer panel A specially selected softwood log used A localized accumulation of pitch in to produce veneer. Peelers are debarked, wood cells in a more or less regular streak. then -turned against a long knife Plastic Overlaid blade which slices off a thin, continu- See MEDIUM DENSITY OVERLAY and ously unwinding sheet of veneer then 5 ply HIGH DENSITY OVERLAY. 5 layer panel clipped to size, dried, graded, repaired and laminated into plywood panels. Plate In wood frame construction, the

Peeler log horizontal lumber member on top Pressure bar and/or bottom of the wall studs which ties them together and supports Plyform the studs or rafters. See B-B PLYFORM. Veneer Plug See REPAIRS.

Knife Lathe chuck

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Plyron® Preservatives PRP® A plywood panel manufactured with a Products which prevent wood See APA PERFORMANCE face for an extra-smooth deterioration due to weather exposure, RATED PANELS. painting and tough wearing surface. excessive moisture or insect attack. May be Exposure 1 or Exterior. Treatments range from chemical pres- Exposure 1 PLYRON is available with a sure-impregnation, as for wood Subframing which supports roof standard, tempered or treated hard- foundations, to application decking where larger beams are board surface and is manufactured of of paints or sealers. main structural supports. D-grade veneer except the ply directly Pressure-Preservative Treated under the hardboard surface, which PURLIN Wood treated with preservative by must be C-grade. Exterior PLYRON is pressure-injecting treating solutions available with a tempered or treated into wood cells. See WOOD surface and is manufactured with FOUNDATION. C-grade plies throughout. PLYRON is ideal for work surfaces, fixtures, built- Primer ins, cabinets and doors, underlayment An undercoat applied to bare wood as a and industrial uses. sealer and base for paint. See FINISHES. Roof PLYRON • EXT • APA • 000 Product Standard PLYRON • EXPOSURE 1 • APA • 000 An industry product manufacturing or PWF performance specification. APA trade- Popping Abbreviation for Permanent Wood marks carrying the PS 1 or PS 2 mark are See NAIL POPPING. Foundation. See WOOD identification by the manufacturer that FOUNDATION. Prefabricated the panel has been produced in confor- In housing, all parts constructed or mance with U.S. Product Standard PS 1 fabricated at the factory so that final for Construction and Industrial Plywood Q construction only involves assembling or Voluntary Product Standard PS 2, and uniting standard parts at the job Performance Standard for Wood-based site. Commonly abbreviated as “prefab.” Structural-Use Panels. PS 1 is a detailed Quality Inspection And Testing See PANELIZED CONSTRUCTION. manufacturing specification and alternate Testing program administered by APA to performance standard developed ensure quality levels in member mills Prefinished cooperatively by the softwood plywood equal to or exceeding those prescribed A ready-to-use panel with industry and the U.S. Department of by U.S. Product Standard PS 1, PS 2 or factory-applied finish – paint, Commerce. PS 1 requirements and a APA’s own performance standards. The overlays or coatings. supplementary set of APA specifications program is based on scientific random sampling. If quality levels are not main- Preframed help ensure that plywood manufactured by APA member mills maintains its con- tained, APA trademark privileges may be Panelized building in which wall, floor sistently high quality. PS 2 is a similar withdrawn until compliance is restored. or roof sections are framed and standard, without the detailed manufac- sheathed at the factory. turing specification, that relies on perfor- Preprimed mance testing to assure that the A panel with a factory-applied primer or structural panels meet realistic, undercoat needing only final finish rigorous standards. after installation.

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R oval shaped with sides tapering to Resawn points or small rounded ends. “” See ROUGH SAWN. patches have parallel sides and rounded R Value Resilient Floor Covering ends. “Sled” patches are rectangular A measurement of thermal resistance, or Any of the vinyl or asphalt-base floor with feathered ends. ability to retard heat transmission. Used coverings (tile or sheet) with enough to compute insulating effectiveness. A plug may be a circular or dogbone “give” to resist deformation or denting shaped wood patch, or a synthetic filler Joint from dropped objects. Resilient floor of fiber and resin to fill openings and coverings installed over APA STURD-I- A joint formed by cutting a groove in provide a smooth, level, durable surface. FLOOR or UNDERLAYMENT panels the surface or along the edge of a board, A shim is a long narrow wood or syn- with “sanded face” provide smooth, stiff or panel to receive another piece. thetic repair not more than 3/16 inch floors for comfortable walking. wide. Various other shapes of plugs RABBET JOINT or patches may be encountered. Reverse Board And Batten PS 1 specifies sizes, shapes and An APA 303 Siding surface treatment. numbers of allowable patches Deep, wide grooves cut into textured in given veneer grades. siding surfaces during manufacture create striking, sharp shadow lines. See APA RATED SIDING. REPAIRS Ridge Beam The top horizontal member of a sloping roof, against which the ends of the Boat patch rafters are fixed or supported.

Rigid Frame Racking Resistance Structural member functioning like an The ability of a panel to resist forces in arch, comprised of studs and rafters the panel’s plane tending to distort it Router patch fastened with plywood gussets. Rigid from its rectangular shape. frame construction eliminates the need Rafter for ceiling or tie members. Sloping supporting member of a roof Ripping immediately beneath the sheathing. Circular plug Sawing wood in the direction of the Raised Grain grain. See CROSS CUTTING. See GRAIN RAISE. Rotary Peel Rated Sheathing See PEELER LOG. See APA RATED SHEATHING. Sled patch Rough Sawn Rated Siding A decorative APA Siding treatment See APA RATED SIDING. imparting a rough, rustic appearance by saw-scoring the surface of a panel Repairs during manufacture. Same as resawn. Any patch, plug or shim in a veneer. A Dogbone plug See APA RATED SIDING. patch is a sound wood insert to replace a defect in veneer. “Boat” patches are Router Patch See REPAIRS. Shim

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S Screws SCREWS Use flat head wood screws for attaching Sanded Panels wood structural panels where nails will not provide sufficient holding power. Interior, Exposure 1 or Exterior Sizes shown below are minimum; use Shank plywood panels factory-sanded for longer screws where work permits. applications where smoothness and Lubricate screws with soap if they are Thread root appearance are important. These panels hard to drive. If used for sheathing, use – with N, A or B-grade faces – are ideal same spacing as recommended for nails. for furniture, cabinets, doors, fences, signs, etc. Sanded panels save time

because they may be finished SCREW SIZES with little or no preparation. Plywood Screw Screw Drill Size Drill Size for Thickness Length Size for Shank Root of Thread Sandwich Panel (in.) (in.) (in.) (in.) See Structural Insulated Panel. 23/32 1-1/2 #8 11/64 1/8 19/32 1-1/4 Sapwood 15/32 1-1/4 #6 9/64 3/32 Living wood of pale color near the 3/8 1 outside of a log. Under most conditions, 1/4 1 #4 7/64 1/16 sapwood is more susceptible to decay than heartwood. Seasoning Shim Removal of moisture from wood to See REPAIRS. An angled or beveled joint in plywood improve its serviceability, usually by air splicing pieces together. The length of drying – drying by air exposure without Shiplap the scarf is 5 to 12 times the thickness. artificial heat – or kiln drying – drying Jointing in which ends or edges are in a kiln with artificial heat. Plywood notch-milled to overlap and veneers are seasoned before lay-up and form a rabbet joint. SCARF JOINT gluing into panels.

Shear Wall SHIPLAP See DIAPHRAGM. Shiplap joint Stud Sheathing Length The structural covering, usually of Siding wood panels or boards, on the outside Panel Thickness surfaces of framing. It provides support for construction, snow and wind loads and backing for attaching exterior facing materials such as wall siding, roof shingles or underlayment in double- layer floors. APA RATED SHEATHING is recommended for conventional applications. See APA RATED SHEATHING.

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Shop Cutting Panel Soffit wood and other panel products may use Panel rejected as not conforming to The underside of the roof overhang. either variety, but are more commonly grade requirements defined in the Wood structural panels are often used manufactured of . Product Standard. Panel identification, as finishing materials for soffits. See HARDWOOD. a separate mark that does not mention Solid Core the Standard, reads: “Shop Cutting Softwood Wood of the coniferous or needleleaved See PLUGGED CORE. Panel – All Other Marks Void.” trees – pine, fir, spruce, hemlock – as Normally a “shop” panel’s defect may Sound Transmission Class distinct from the hardwood of the be eliminated by cutting the panel into See STC. deciduous or broadleaved trees – oak, smaller pieces for applications not ash, maple, walnut. The term has only a governed by building codes. Spacing general reference to actual wood hard- See PANEL SPACING. Siding ness. Construction and industrial ply- See APA RATED SIDING.

Sill Plate SOFFITS The lowest framing member of a struc- ture, resting on the foundation and supporting the floor system and the uprights of the frame.

Single Floor A single-layer wood structural panel flooring system combining subflooring Closed soffit and underlayment. See APA RATED

STURD-I-FLOOR. Strength axis Single Wall See APA STURD-I-WALL.

Sized For Spacing A notation in APA RATED SHEATHING and RATED STURD-I-FLOOR trade-

marks indicating panels may be Strength axis trimmed during manufacture to length Open soffit and width tolerances of +0, –1/8 inch. This trimming is designed to encourage proper panel spacing. See PANEL SPACING.

Sled Patch See REPAIRS.

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Span Rating applied horizontally direct to studs testing. Manufactured with Exterior or The number that appears in the trade- spaced 16 or 24 inches on center, pro- Exposure 1 durability classifications. See mark on APA RATED STURD-I-FLOOR, vided horizontal joints are blocked. also APA RATED SHEATHING. APA RATED SHEATHING and APA When RATED SIDING is used over APA RATED SIDING panels. Two numbers RATED SHEATHING or lumber, the separated by a slash (e.g., 24/0, 32/16, Span Rating refers to the maximum APA APA THE ENGINEERED THE ENGINEERED 48/24) appear on APA RATED recommended spacing of vertical rows WOOD ASSOCIATION WOOD ASSOCIATION SHEATHING. The left-hand number is of nails rather than studs. RATED SHEATHING RATED SHEATHING 32/16 15/32 INCH STRUCTURAL I the maximum recommended center-to- 15/32 INCH Panels with a given Span Rating may be SIZED FOR SPACING 32/16 EXPOSURE 1 SIZED FOR SPACING center spacing of supports in inches manufactured in more than one thick- 000 EXPOSURE 1 STRUCTURAL I RATED 000 when the panel is used for roof sheath- DIAPHRAGMS-SHEAR WALLS PS 1-95 C-D PRP-108 ness, and vice versa, because of varying PANELIZED ROOFS PRP-108 HUD-UM-40C ing with long dimension across supports panel compositions and configurations. (unless the strength axis is otherwise identified). The right-hand number is Species Group Structural Insulated Panel the maximum center-to-center spacing See GROUP NUMBER. A section of layered construction of supports in inches when the panel is made up of high-strength structural Stains used for subflooring with long dimen- wood panel faces, or “skins,” attached See FINISHES. sion across supports. When a panel is to both sides of low-density core materi- applied as wall sheathing, a rating of STC als such as plastic foam or honeycomb 24 or more means the panel can be Sound Transmission Class. A measure of paper fillers. Sometimes referred to as applied to studs spaced 24 inches on the ability of a wall or floor assembly to sandwich panel or stress-skin panel. center. A rating less than 24 means the reduce noise transmission. panel can be applied to studs spaced 16 inches on center. APA RATED Stressed-Skin Panel STRUCTURAL INSULATED PANEL SHEATHING panels may be applied as An engineered structural panel assembly wall sheathing either vertically or hori- for roof deck or floor applications built zontally. In all cases the panel should be of plywood sheets glued to framing applied continuous over three or more members. The quick-covering assembly supports. has greater load carrying capacity than would its individual members if The single-number Span Ratings on APA installed separately. RATED STURD-I-FLOOR panels (16, 20, 24, 32 or 48 oc) denote maximum Stringer recommended center-to-center spacing A lumber member supporting a series between floor joists with panels laid of cross members. Frequently applied with long dimension across three or to stair supports. Stud more supports. The basic vertical framing members of Structural I Similarly, the single-number Span walls, usually 2x4s. Studs are tradition- Unsanded grade for use where shear Ratings on APA RATED SIDING panels ally spaced 16 inches on center, and cross-panel strength properties are are the maximum recommended center- sometimes 24 inches as in the of maximum importance, such as panel- to-center spacings of studs (16 or Engineered 24" Framing System. ized roofs and diaphragms. All plies in 24 o.c.) when the panel is applied verti- See SPAN RATING. Structural I plywood panels are special cally direct to studs (or over nonstruc- improved grades and panels marked Sturd-I-Floor tural wall sheathing such as fiberboard, PS 1 are limited to Group 1 species. See APA RATED STURD-I-FLOOR. gypsum or rigid foam insulation sheath- Other panels marked Structural I Rated ing). All RATED SIDING panels may be Sturd-I-Wall qualify through special performance See APA STURD-I-WALL.

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Subflooring Testing Agency edge joint is particularly efficient in APA RATED SHEATHING panels See APA – The Engineered Wood transferring the load across the joint. applied directly over floor joists which Association and QUALITY INSPECTION Some APA RATED STURD-I-FLOOR will receive an additional underlayment AND TESTING. T&G panels measure 47-1/2 inches layer. Wood structural panels provide across the face. ® strength and stiffness. They also reduce Texture 1-11 APA trade name for a special RATED the number of floor joints as compared SIDING panel 19/32 inch or thicker with board sheathing. See also with 3/8-inch-wide vertical grooves UNDERLAYMENT. typically spaced 4 or 8 inches on center. Swelling Shiplapped edges maintain pattern See EXPANSION and PANEL SPACING. continuity when installed. See APA RATED SIDING. Synthetic Repairs Touch-Sanded Panels See REPAIRS. Textured Plywood Wood structural panels “sized” to uni- Panels with a variety of machined sur- form thickness by light surface sanding face textures. Available as Exterior with during manufacture. skips are fully waterproof glueline for siding and T admissible. Normally applied to C- other outdoor uses and for interior wall Plugged faces. paneling. See APA RATED SIDING. T-Beam Trademark Beam resembling a “T” in cross section. 303® Specialty Siding See APA TRADEMARK. Several side-by-side T-beams acting as a See APA RATED SIDING. unit may form a floor. This principle Truss Tongue-And-Groove Joint accounts for the increased stiffness A combination of members usually A system of jointing in which the rib or of glued floors. arranged in triangular units to form a tongue of one member fits exactly into rigid framework for supporting loads Telegraphing the groove of another. A specially over a span. Parallel chord trusses are Show-through on a smooth overlaid designed APA – The Engineered Wood also used for floor and roof supports. plywood panel surface of underlying Association tongue-and-groove panel grain or defects.

TRUSS Gusset Web members

Upper or compression chord

Gusset

Lower or tension chord Gusset

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2-4-1® Underlayment Grade combined with insulation to control Synonymous with APA RATED PS 1-designated, touch-sanded panels condensation. A vapor retarder should STURD-I-FLOOR 48 oc. 2-4-1 is a designed as a base for finish flooring be installed on the warm side of walls. 1-1/8-inch-thick all-veneer panel with such as carpeting (and tile or linoleum Veneer an Exposure 1 durability classification. when specified with a sanded face) and A thin sheet of wood laminated with It’s designed for single-floor applications installed over structural subflooring others under heat and pressure to form over 2x supports spaced 32 inches on such as APA RATED SHEATHING. plywood, or used for faces of composite center or over 4x supports 48 inches on These panels are manufactured with panels. Also called ply. center. 2-4-1 may also either interior or exte- be used in Heavy rior glue – the latter Veneer Grade Timber roof construc- APA designed for applica- APA The standard grade designations THE ENGINEERED tions subject to long THE ENGINEERED tion. Available WOOD ASSOCIATION WOOD ASSOCIATION of softwood veneer used in panel construction delays or as specified with RATED STURD-I-FLOOR UNDERLAYMENT manufacture. The six grades are: square edge or 1-1/8 INCH similar moisture expo- GROUP 1 48oc 2-4-1 N Special order “natural finish” SIZED FOR SPACING sure. Underlayment EXPOSURE 1 tongue-and-groove EXPOSURE 1 T&G 000 veneer. Select all heartwood or all joint. See APA RATED 000 panels are identified PS 1-95 PS 1-95 UNDERLAYMENT sapwood. Free of open defects. STURD-I-FLOOR. by Group number. Allows some repairs. Unsanded Panels A Smooth and paintable. Interior, Exposure 1 or Exterior Neatly made repairs permissible. U sheathing grade panels designed for Also used for natural finish in less utility applications and left unsanded for demanding applications. Underlayment greater stiffness, strength and economy. B Solid surface veneer. Router or sled A material applied over subflooring and repairs and tight knots permitted. directly beneath nonstructural finish flooring, such as tile or carpeting. Wood C Improved C veneer with splits V Plugged panel underlayment provides a smooth limited to 1/8 inch in width and surface for finish flooring and excellent knotholes and borer holes limited to Vapor Retarder puncture and indentation resistance. 1/4 inch by 1/2 inch. A material (such as plastic film) which See also SUBFLOORING, PLUGGED C Knotholes to 1 inch. Occasional controls moisture transmission through CROSSBAND UNDER FACE and knotholes 1/2 inch larger permitted walls and other building elements. Often UNDERLAYMENT GRADE. providing total width of all knots and knotholes within a specified section Underlayment C-C Plugged Exterior VAPOR RETARDER Gypsum does not exceed certain limits. Limited wallboard splits permitted. Minimum veneer grade An Exterior underlayment panel with a Insulation touch-sanded C-Plugged face ply. permitted in Exterior plywood. Common uses include underlayment in D Permits knots and knotholes to conditions of severe moisture or humid- 3 inches in width, and 1/2 inch larger ity (bathrooms, kitchens), refrigerator or under certain specified limits. controlled atmosphere Limited splits permitted. storage rooms, exterior APA Void balconies and decks, THE ENGINEERED WOOD ASSOCIATION bins, tanks, Plywood See CORE GAP. C-C PLUGGED siding boxcar and truck GROUP 1 floors and linings, and EXTERIOR 000 Warm-side open soffits. PS 1-95 vapor retarder

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W Warping Z Bending or twisting from a straight line. Waferboard An improperly seasoned piece of lumber Z Flashing may warp when exposed to heat or Panels manufactured from reconstituted A Z-shaped piece of galvanized steel, moisture. To reduce the possibility of wood wafers, as opposed to strands, aluminum or plastic installed at hori- warping, protect wood panels from bonded with resins under heat and zontal joints of panel siding to prevent dampness or moisture and follow APA pressure. See also ORIENTED water from entering wall cavity. spacing recommendations. Painting and STRAND BOARD. water-repellent dips will minimize mois- Wainscot ture absorption. Sealing all edges and FLASHED JOINT – HORIZONTAL The wooden lining of the lower part of back-priming also reduces the chances an interior wall. of warping in cabinet doors. Blocking See PANEL SPACING. between studs Waler Horizontal timbers used to brace Water Repellents concrete form sections. Wood preservatives with water-resistant properties.

WALER Web Plywood concrete form See BOX BEAM and TRUSS.

Waler Wicking The tendency of wood to draw moisture up through its cells by capillary action in the direction of the grain. Aluminum, plastic or galvanized steel flashing Wood Foundation Snap tie A residential and light frame foundation Vertical bracing system utilizing pressure-preservative- Snap tie shoe treated plywood panels and wood fram- ing in place of poured concrete footings and masonry or poured concrete walls. The system is commonly known as the Permanent Wood Foundation (PWF). The system can often be installed on a prepared site in less than half a day in nearly any weather, speeding construc- tion and reducing costs. The PWF is also applicable to crawl-space founda- tion construction. The product use recommendations in this publi- cation 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 conditions under which engineered wood prod- ucts are used, it cannot accept responsibility for product performance or designs as actually con- structed. 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.

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PANEL HANDBOOK & GRADE GLOSSARY GLOSSARY

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, get in touch with your nearest APA regional office. Call or write:

WESTERN REGION 7011 So. 19th St. P.O. Box 11700 Tacoma, Washington 98411-0700 (253) 565-6600 Fax: (253) 565-7265

EASTERN REGION 2130 Barrett Park Drive, Suite 102 Kennesaw, Georgia 30144-3681 (770) 427-9371 Fax: (770) 423-1703

U.S. HEADQUARTERS AND INTERNATIONAL MARKETING DIVISION 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 (253) 620-7400 E-mail Address: [email protected]

(Offices: Antwerp, Belgium; Bournemouth, United Kingdom; Hamburg, Germany; Mexico City, Mexico; Tokyo, Japan.) For Caribbean/Latin America, contact headquarters in Tacoma.

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. X505R/Revised April 1997/0300

APA The Engineered Wood Association

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