GDE,G210,Transport.0 4/21/00 9:58 AM Page 1

APA The Engineered Association

INDUSTRIAL USE GUIDE

TRANSPORT EQUIPMENT GDE,G210,Transport.0 4/21/00 9:58 AM Page 2

APA The Association

DO THE RIGHT THING RIGHT™

Wood is good. 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. 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 I-joists, glued laminated timbers, laminated veneer , and is the right thing to do.

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, 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 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.

Manufacturing wood is energy Percent of Percent of efficient. Wood products made up Material Production Energy Use 47 percent of all industrial raw materials Wood 47 4 manufactured in the United States, yet consumed only 4 percent of the energy Steel 23 48 needed to manufacture all industrial raw Aluminum 2 8 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,G210,Transport.0 4/21/00 9:59 AM Page 3

CONTENTS

PANEL TYPES AND PROPERTIES . . .4 Conventional Plywood ...... 4 APA Performance- Rated Panels ...... 4 PA trademarked plywood has been FRP Plywood ...... 7 indispensable to transport equipment Metal Overlaid Plywood ...... 8 Foam Core Insulated Panels . . . .8 manufacture for nearly 50 years. It A TRUCK, TRAILER has earned a sterling reputation as a AND INTERMODAL CONTAINER BODIES ...... 9 lightweight, reliable and cost-efficient structural Panel Selection ...... 9 material. In trucks, trailers, intermodal contain- ...... 9 ers, rail cars, pickup trucks and recreational Joints ...... 10 Walls ...... 14 vehicles of all kinds, plywood and other wood ...... 17 structural panels represent the logical choice for Floors ...... 17 bodies, linings, interior and numerous Roofs ...... 18 other applications. Cargo Restraint Devices ...... 18 FRP Plywood Fabrication and Repair ...... 18 This manual is for transport equipment design- Metal Overlaid ers, engineers and manufacturers. It covers APA Plywood Fabrication ...... 20 TRUCK, TRAILER AND trademarked wood structural panel grades and RAIL CAR LININGS ...... 21 properties, structurally overlaid panels, design Panel Selection ...... 21 criteria, fastener data and other key topics. Truck and Trailer Front-End Structures ...... 21 Panel Installation ...... 22 Since the design of transport equipment is an Cargo Restraint Devices ...... 22

intricate and evolving science, this publication RECREATIONAL VEHICLES AND BUSES ...... 26 does not present complete unit designs. It does, Panel Selection ...... 26 however, provide the most recent and accurate Floors ...... 27 criteria available on appropriate wood structural Walls ...... 28 panel design aspects. Final decision on suitable Roofs ...... 28 Framing ...... 29 performance level is left to the design engineer. Fasteners ...... 29 Adhesives ...... 31

FASTENERS ...... 31 Estimating Allowable Design Loads ...... 31

ADDITIONAL INFORMATION . . .35 GDE,G210,Transport.0 4/21/00 9:59 AM Page 4

PANEL TYPES AND PROPERTIES

Conventional Plywood Strength And Stiffness. Plywood manufactured under U.S. Product Standard PS 1 for Construction and Industrial Plywood may be made from over 70 species of wood. These species are divided by strength and stiffness into five groups. Group 1 species are the strongest and stiffest, Group 2 the next strongest and stiffest, and so on. The group number in the APA trademark is part of the correct grade designation for the sanded panels commonly recommended and specified for transport lining and recreational vehicle applications. The strength of wood along the grain is many times greater than across the grain. By cross-laminating layers of veneer, plywood provides along-the- Table 2 provides concentrated load Table 3 documents plywood resistance to grain strength in both directions. Yet strength information for Group 1 forklift tine penetration, a major cause of relative to its strength, plywood is a sanded plywood thicknesses. truck liner damage. According to tests of relatively lightweight material and can Span length within the limits normally different thicknesses, face grain direction thus help minimize tare – an important associated with a plywood thickness has of a panel only slightly influences total consideration in all transport applica- minimal influence on concentrated load tine penetration resistance. The impact tions. The relative strength of plywood capacity. Loads applied to a free unsup- resistance of a bare 1/4-inch plywood lining panels is given in Table 1. ported edge may be 50 to 90 percent of panel can be doubled by substituting a Plywood also exhibits excellent the load shown for center panel loca- special 1/4-inch plywood liner panel stiffness, or resistance both to deflection tions. If applied by a four-inch disc, with 0.050-inch-thick (1.5 oz/sq ft) under uniform and concentrated loads loads may be 20 to 50 percent greater fiberglass mat face. Thicker plywood and to racking forces. This stiffness than those charted. with more glass increases penetration often permits plywood to be used with resistance proportionately. Plywood also can withstand repeated less framing or bracing than other impact without cracking or crumbling materials may require. APA Performance-Rated Panels because of its cross-laminated construc- Wood structural panels of compositions Plywood withstands heavy concentrated tion. Since it has no of cleavage, and configurations other than conven- loads because the cross-lamination it’s extremely resistant to splitting. tional all-veneer plywood are also avail- distributes stress over a wide area. able from APA member mills. These

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TABLE 1 RELATIVE STRENGTH OF PLYWOOD LINING PANELS

Face grain ⊥ to supports

Face grain || to supports

660 390

530 230

360 110

100 20 160 30

1/4-inch 11/32-inch 15/32-inch 19/32-inch 23/32-inch Sanded Sanded Sanded Sanded Sanded

Group 1 species are most commonly used as lining. Group 2 and 3 plywood is 73% as strong and Group 4 is 67% as strong. The table above is valid for comparing panels within any one species Group.

panel products are manufactured according to APA performance standards TABLE 2 TABLE 3 that set strength, stiffness and durability CONCENTRATED-LOAD FORK TINE criteria for specific construction applica- STRENGTH – 2 INCH PENETRATION RESISTANCE LOADING DISC Round tip fork tine 1/2 in. x 5 in. tions. Panels include oriented strand Face Grain Across Supports penetrating Group 1 plywood on supports 16 in. o.c. board (OSB) and composites (reconsti- Ultimate tuted wood cores bonded between Load (lb) Energy to Penetrate 2800 veneer faces). (in.-lb) 2400 Abrasion Resistance. In truck lining 3200 2000 applications wood structural panels 2400 1600 provide a smooth surface with relatively 1600 1200 few joints, making it ideal for sliding and 800 Penetration 800 resistance skidding palletized and loose-loaded 0 400 freight. Snag-free panel surfaces reduce 1/4 3/8 1/2 5/8 3/4 0 Plywood Thickness (in.) costly damage to boxed and bagged 1/4 3/8 1/2 5/8 3/4 goods and possess high resistance to Plywood Thickness (in.) prolonged friction and abrasion. Group 1 Sanded For extra protection against fork tine 12 in. span 16 in. span damage, replaceable scuff panels are 16, 24 in. span often installed over the bottom two feet 24, 32 in. span

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of a liner. Table 4 rates the surface scuff The ability of a material to retard heat resistance of typical plywood panels flow is termed thermal resistance (R). TABLE 4 used in lining applications. To establish The R values of several panel SURFACE SCUFF* a comparative scale, bare APA trade- thicknesses are given in Table 5. RESISTANCE RATING Panel Rating marked A-C Group 1 plywood has been The burn resistance requirements for given a rating of 100. Remember that Common plywood linings materials used in the occupant compart- Bare Group 1 plywood (A-C) 100 scuff panel performance depends upon ments of motor vehicles are specified in High density overlay Group 1 solid wood structural panel backing. the Federal Motor Vehicle Safety Standard plywood (HDO A-A) 100 Without such backing, a scuffing load No. 302, Flammability of Interior Materials Coated liner panels will quickly penetrate a lining. in Passenger Cars, Multipurpose Passenger 0.050-inch-thick FRP bonded to plywood 189 Dimensional Stability. APA trademarked Vehicles, Trucks and Buses. Tests con- 0.030-inch-thick FRP plywood is an engineered product with ducted at the APA research laboratory bonded to plywood 167 known, predictable properties. Press- have shown that plywood of various Structural overlaid composites dried at the mill, it is never “green.” thicknesses and with face grain oriented 2.67 oz/sq ft (24 oz/yd) woven roving on plywood 211 And by restricting expansion and con- both parallel and perpendicular to the 2.00 oz/sq ft chopped traction within individual plies, its long dimension of the specimen easily roving SMC on plywood 178 cross-laminated construction helps meets the requirements of Motor Vehicle Scuff panel over plywood backing deliver exceptional dimensional stability Safety Standard No. 302. Results in all 0.120-inch-thick FRP scuff in the plane of the panel. From oven-dry tests showed a burn rate of zero as panel, plywood backing 400 to maximum saturation, plywood panels measured by the standard’s require- 0.100-inch-thick FRP scuff panel, plywood backing 267 swell an average of only 2/10 of one ments. In no instance did the flame Less used plywood linings percent in length or width. Plywood reach the 1-1/2-inch starting mark of Bare Group 2 plywood (A-C) 89 therefore remains intact and strong the specimen before self-extinguishing. Bare Group 4 plywood (A-C) 67 under extremes of temperature *Comparative resistance to face damage Compatibility. Wood structural panels from a load applied through a 3/4-inch- and moisture. diameter hemispherical steel loading head can be used in combination with other dragged across the surface. Workability. Wood structural panels wood products, metals or plastics. They are easily worked with ordinary . will not contribute to electrolytic action

They take and hold fasteners – even when used with metals. They won’t rust TABLE 5 near panel edges – without splitting. or corrode, even when exposed to harsh WOOD STRUCTURAL PANEL Wood structural panels’ workability and chemicals. They bond with many THERMAL RESISTANCE strength properties permit great latitude durable adhesives. And they accept a Panel Thermal Thickness (in.) Resistance (R) in placement of interior hardware, such wide variety of field-applied finishes, 1/4 0.31 as required for cargo restraint devices, including conventional , stains and 5/16 0.39 shelving, or dividers. , as well as vinyls, epoxies and 3/8 0.47 latex-based products. Thermal, Acoustical And Fire-Resistant 7/16 0.55 Properties. A wood structural panel is a Availability. APA trademarked panels 1/2 0.62 natural insulator, a good sound barrier are available throughout North America 5/8 0.78 and an effective fire resister. Large panel in a wide variety of thicknesses, types 3/4 0.94 size minimizes the number of joints that and grades. Besides the standard prod- 1 1.25 can lose heat or refrigeration, “leak” ucts, coated and overlaid plywood pan- 1-1/8 1.41 airborne noise or allow flame passage. els have gained wide acceptance in the transportation industry. High Density Overlay (HDO), for example, has a resin-impregnated fiber overlay that provides a smooth, highly chemical- resistant surface.

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10 x 45 feet and larger, requiring only perimeter framing. That’s like adding 3 feet of length in a 40-foot trailer. FRP plywood vans and containers also are easier to load and unload because there are no projections or framing along the walls or ceiling to snag cargo or forklift masts and tines. Easy Repair. FRP plywood vans and containers not only require less mainte- nance than all-metal equipment, but also simplify repairs. When traffic acci- dents or gross mishandling causes severe damage, repair requires only ordinary tools, skills and materials. Even a puncture can be repaired by simply cutting out the damaged section, insert- ing an FRP plywood plug, and resurfac- ing the area with fiberglass and resin – a technique much like auto body repair. Since no heat is required, temporary repairs can be made even while vans or containers are loaded. FRP Plywood urban areas where narrow loading docks Plywood panels overlaid with structural and streets literally nick, gouge, dent Cargo Damage Reduction. In ordinary faces of fiberglass-reinforced plastic and scrape most vans into unservice- metal vans, the major sources of (FRP plywood) combine the proven ability. FRP plywood also has high both maintenance and cargo damage qualities of conventional plywood resilience – it resumes its original reported by fleet owners are corrosion, and several advantages of particular shape after being subjected to excep- rust and subsequent moisture leakage. relevance to transport applications. tionally severe bulging loads, such Since FRP plywood is unaffected by salt and calcium chloride, corrosion and Durability. The chief advantage of as from rolls of carpeting. rust are eliminated. Large FRP plywood FRP plywood panels for truck, trailer Increased Cubage. FRP plywood truck, sheet size means fewer joints, and thus and intermodal container bodies is trailer and intermodal container bodies less damage to equipment and cargo exceptional durability. Users report the provide more usable cubage than similar from water leakage. In addition, ply- smooth, hard-surfaced panels minimize metal units (4 to 7 percent more, wood’s favorable thermal insulation operating costs, resist damage and wear, depending on design) because no space- properties help prevent moisture con- and deliver superior long-term perfor- consuming stiffeners or intermediate densation on interior surfaces, which mance. FRP plywood is nearly twice framing members are required for as strong as ordinary plywood. Field strength. Thin-sectioned FRP panels can experience proves that it has excellent be produced in sizes from 4 x 8 feet to characteristics for the most rigorous applications, including vans operated in

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reduces the chances of water-damaged Cost Advantage. The overriding reason Depending on composite thickness cargos and rotting or moldy interiors. for the proliferation of FRP plywood in and the type of overlay, metal overlaid Design Flexibility. The properties and the transport industry is its long-term plywood may be 10 times as strong as characteristics of FRP plywood yield cost advantage to equipment owners. conventional plywood. Special panels design freedom for equipment manufac- While manufacturers report that can also be designed for demanding turers and more flexible equipment for FRP plywood usually costs more than engineered assemblies, such as metal purchasers. Scuff resistance can be sheet metal, it also reduces manufactur- over fire-retardant-treated plywood core increased in vulnerable areas with ing labor costs. The cost of finished for maximum fire resistance, or lead double fiberglass overlays. FRP and metal units, therefore, is overlays for radiation and acoustical shielding. New combinations of ply- Special panels are available for usually comparable. wood and various metal overlays are drop-frame trailers. Integral flush sky- Savings accrue to the user/owner in the constantly being investigated to increase lights or side doors can be located form of greater durability, reduced main- cost/performance efficiency. almost anywhere since openings are not tenance requirements and improved major structural considerations. Framing cargo protection. When calculated on a Foam Core Insulated Panels section variety also provides many cost-per-ton mile basis, therefore, FRP Sandwich panels of fiberglass, plywood options in exterior appearance and trailers and containers compare very and foam have been developed for electrical wire routing. favorably with other types of units. refrigerated trailer usage. While insula- Since interior modification of FRP Moreover, wind tunnel resistance tion is the prime requirement, foam core plywood is simple, owners have a wide tests have shown that smooth-sided insulated panels must also possess high choice in installing or modifying cargo- trailers “pull” as much as 12 percent strength and unusual impact and restraint hardware, wiring, compartmen- more efficiently than trailers with abuse resistance. talization, racks, shelving or other exposed posts. Tests that a layer of plywood accessories. Hardware and fasteners can In short, FRP units offer competitive under the FRP skin prevents premature be installed anywhere on wall or ceiling initial cost and substantial breakdown of the foam core. Assuring surfaces. And FRP panels accept and long-term savings. composite action between panel firmly retain a wide range of elements is essential to maximize mechanical fasteners. Metal Overlaid Plywood stiffness and strength. Metal overlaid plywood panels offer Aesthetic Appeal. FRP plywood vans The lightweight foam core keeps the tare advantages similar to those of FRP ply- and intermodal containers constitute weight low and provides good insula- wood, but their special characteristics moving billboards for their owners. tion, but is sensitive to crushing from make them particularly valuable for many When colored, fiberglass-reinforced modest surface pressure. The plywood transportation applications where maxi- plastic provides long-lasting visibility and layers sandwiching the foam core help mum strength and durability are clean lines. Corporate logos or slogans distribute blows and concentrated pres- required. Their main use has been roll-up apply easily and retain their fresh appeal sure. Even when panels are cut or punc- or swinging doors for vans. But metal for years so that equipment advertises tured, the ability of plywood to spread overlaid plywood is also used extensively the operating firm around the clock. impact forces localizes damage. as floor and interior panels for rapid transit, passenger and baggage cars, for escalator balustrades and for slave pallets.

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TRUCK, TRAILER Framing FIGURE 1 AND INTERMODAL Perimeter framing for trucks and CONTAINER BODIES containers must connect the self- supporting structural FRP plywood Mastic bed panels and still meet other requirements Panel Selection Bolts with peculiar to each vehicle. Framing is Wood structural panels can be used for silicone seal often shaped to perform several func- floors, walls, roofs, doors or any combi- FRP plywood Light wire tions for design simplicity. Adequate nation of these applications in trans- Mastic strength is basic; ease of assembly and portation equipment. In some cases a repair, moisture resistance and appear- conventional panel may be the best ance are also important considerations. choice; in others, a plywood panel overlaid with resin-impregnated fiber, or Figures 1-6 illustrate available frame a panel of plywood overlaid with metal section design options that provide or fiberglass-reinforced plastic (FRP) durable, watertight joints. Aluminum may perform more satisfactorily. and steel frames – and designs combin- FIGURE 2 ing both metals – are widely used. The basic considerations influencing Shapes are frequently developed for design include vehicle usage (e.g., inner- individual manufacturers, but some Roof sheet city delivery vs. long-haul); climate (cor- Wiring recess adapt traditional extrusion designs. rosion resistance of framing materials, reflective roof coloring in warm climate, The top side rails in trailers not only Rub rail etc.); physical environment (rental units, connect roofs and sides, but also form Bolt bearing strip fleet operation, type of loading, etc.); a protective conduit for electrical wiring. production facilities; and government Wiring is usually routed outside the regulations for safety and cleanliness. body for easy service and modification. Strength and stiffness of wood structural Corner uprights may be designed to panels or structural overlaid panels are streamline, to improve appearance, or also important design considerations. to efficiently integrate rear hinges. This manual details the comparative Rear vertical framing and doors are often FIGURE 3 strength and stiffness of bare plywood combined for unit assembly. Standard and a number of different overlays as well extrusions for truck body front corners as approaches to applying them. While are compatible with most overlaid ply- Rivets this design section presents examples of wood panels. Slots permit bolt or rivet truck and trailer applications to illustrate fastening with acceptable edge distances. design recommendations, most of (See Figure 3.) Trailer-body builders Corner post standard the information also applies to extrusion intermodal containers. Mastic

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frequently use a formed metal front Moisture Resistance. The face and back corner with two 45-degree angles. (See of FRP plywood are impervious to mois- FIGURE 4 Figure 4.) This reduces wind resis- ture, but panel edges are not. Manufac- tance and provides maximum inside turers may seal edges with resin to T-nut, hex head pronged or similar cubage with adequate tractor clearance. protect against moisture absorption Hex head Bottom horizontal framing may be during assembly and handling, but alternate designed to connect with floor joists and even sealed edges require additional function as a rub rail. Or the rub rail may consideration for permanent protection. be separate. (See Figures 5 and 6.) Unsealed panel edges must be protected from moisture absorption during assem- Framing stiffness is discussed in detail Formed bly and handling. Final assembly design Mastic aluminum corner in the section on “Fasteners,” page 31. should also prevent direct moisture With 1/4-inch fasteners torqued to pickup along panel edges. Test values 125 in.-lb, 6 inches o.c., steel framing show a dry joint can be from 20 to should be 1/8 inch thick to prevent 45 percent stronger than a water-soaked dimpling, subsequent damage to side FIGURE 5 joint. Eliminating moisture demands panels, and bowing between fasteners careful design and early damage repair. which can destroy the moisture seal between frame and panel. Since alu- Both the frame and rub rail should be minum framing members are usually stiff enough to resist fastener dimpling, extrusions, thickness must be adequate which can cause excessive cracking of or ribs added to prevent dimpling of the gel coat (if not protected by mastic) Floor fasteners into the framing. Framing and and allow moisture penetration. Dimpling can be avoided with adequate Shaped fasteners should be compatible to pre- framing Beam vent corrosion between dissimilar mate- framing, by using fasteners with large rials. Rust-preventative coating for all enough heads or washers, or by using steel and welds is highly recommended. more fasteners to reduce clamping force per fastener. Joints Years of field experience with various FIGURE 6 Design of joints between metal framing panel-to-frame connections have proven and overlaid plywood panels requires that the double seal illustrated in three major considerations: first, water- Figure 7a is the best watertight joint. tightness, including frame stiffness, A panel is typically bedded in mastic caulking, gasketing and fastener spac- Extended against the frame. An external of rub rail ing; second, strength, which depends high-performance, exposure-resistant largely on fastener design; and third, Floor sealant like silicon, urethane, or Thiokol stiffness, which influences durability is then applied along the joint between and depends on fasteners and mastic. the framing edge and panel surface. This Beam second seal precludes standing water on the edge of the framing.

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used in FRP plywood equipment. FIGURE 7 Self-locking fasteners counter expansion and contraction of materials as well Silicone seal Broken Seal as fastener vibration. Pilfer-proof fasteners with smooth heads may be required, particularly in contain- ers designed for international use. One of the most rigid fasteners of this type

Not over 12 times framing thickness Short overlap Mastic tested by APA is a bolt fluted to engage in joint the metal frame. Impacted into a force- Framing fit hole in the frame, it forms a solid At least 1" or 4 bolt diameters connection held in place with a T-nut driven from the inside. This fastener also aballows one-man tightening. Even though fasteners are mechanically The interior mastic seal may be more prevent excessive flexing between them, tightened, gasketing the head and nut of precise and reliable if applied in tape and an elastic sealant helps maintain each one is recommended. Fasteners are form. The mastic or foam is coiled on the watertight seal. available with a small recess around the paper in a ribbon of consistent thick- Moisture drains should be provided in underside of the head to receive a flexi- ness and width, and can be applied a fastening and sealing system so that ble washer-type gasket. All fasteners manually to assure an unbroken . moisture penetrating a joint has an should be corrosion resistant to guard The mastic should compress evenly and escape route. On rare occasions, trapped against moisture and electrolytic action fill the joint as fasteners are tightened. moisture in a joint forms an electrolytic between dissimilar metals. This use of mastic between surfaces is connection between dissimilar metals. Joint designs vary, but Figure 8 dictated by watertight requirements A close fit between bolt and bolthole illustrates single shear with bolts extend- but it may reduce joint stiffness. See increases joint stiffness. A common ing through rub rail, FRP plywood and section on “Fasteners” page 31. practice is to panel holes after the steel frame. The bolts are in single shear An alternative to the two-seal caulking panel is in place using the predrilled because the rub rail is separate from the system shown here is a sealant-adhesive frame holes as guides. frame, and the bolt-to-frame load is system throughout the joint. The advan- carried through the joint between frame Fasteners. Test results on fastener tages of bonding the framing to the and panel only. With single-shear strength appear at the end of this panel (and the possibility of using fewer attachment, the panels may be drawn section with a discussion on their mechanical fasteners) must be weighed progressively tighter against the frame- use in joint design. against the drawback of a material work. Alignment is assured by requiring mixing and gun applications. Common bolts, special threaded the holes after the panel is in place. fasteners, welded-stud bolts, non- The joint fasteners should hold the threaded fasteners such as rivets, and framing and the panel firmly together so pin and swaged-collar bolts are widely panel flexing will not break the seal (Figure 7b). Lapping the panel over the framing three or more inches will help

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Double-shear joints (Figure 9) contribute A suggestion for determining bolt significantly greater strength but assem- spacing involves dividing the shear load FIGURE 8 bly requirements are more complicated. applied to that part of the connection by Accurate alignment of the panel and rail the allowable load per bolt. The result FRP plywood

is necessary before fastening, and work- gives the number of fasteners required. Silicone seal Floor ing tolerance is reduced. Panel insertion Determination of this shear load is a may be more complicated in double- matter of structural design and follows Bolts staggered in two rows shear designs, and adequate mastic standard engineering practice. coverage can be very difficult. In addition to affecting strength,

Rub rail Floor beam Tests with both static and dynamic bolt fastener spacing also influences the loading prove that fastener clamping quality of the water seal, overall stiff- Silicone seal action significantly influences joint suc- ness, and appearance of the unit. (See Lower rail Mastic cess. Clamping can be increased with Figure 10.) Fewer fasteners at wider greater bolt torque up to the limits of spacings increase the possibility of bow- thread strength and the resistance of the ing in the frame between fasteners, and frame and panel to dimpling. In some of resulting weak points in the moisture FIGURE 9 cases it may be desirable to use hard- seal. Moreover, larger bolts usually ened steel bolts with higher tensile load require heavier side rails to reduce dim- Silicone allowances and greater shear strength. pling. Successful designs have used bolt seal FRP plywood Any framing that inhibits tight clamping spacings from 2 to 8 inches o.c. with Bolt Lower rail will reduce long-term performance diameters 1/4 inch and greater. Six-inch double of the bolted connection. spacing of 5/16-inch diameter bolts is shear Joint slip due to cyclic loading should common, but number of bolts may be Ribs Floor also be considered. There is still some doubled in high shear areas. Bolts are protect bolt heads question whether mastic in the joint usually arranged in a single straight Mastic Clip Floor increases such slip. Although APA static row or staggered in two rows. angle beam load tests showed no increase in slip with Tests with varying edge distances the addition of mastic, tests with cyclic (centerline of bolthole to panel edge) loads did show significant reduction, show that ultimate strength of the joint both in ultimate load and in stiffness. But increases with increased edge distance. a survey of manufacturers showed no However, joint strength under dynamic FIGURE 10 significant slip problems with the mastic. loading is affected to a lesser degree in Fillet of resilient 2 bolt diameters In fact, connection designs like those the practical range of edge distance of weatherproof nimimum, 12 times illustrated in Figures 1-10 have performed four bolt diameters and greater. As a rule sealant framing thickness maximum satisfactorily in service with bolt spacings of thumb, edge distance should be at up to 6 inches o.c. Although mastic in least one inch or four bolt diameters, the joint may reduce the capacity of a whichever is greater. bolted connection to resist maximum- Static Bolt Loads. Table 6 lists intensity cyclic load, mastic contributes APA-tested bolt loads at two slip levels to watertightness, and actual in-service

and at ultimate load. It includes three Overlaps as much as possible up to 6" loads do not seem to develop this maxi- different plywood core thicknesses, and Mastic mum intensity. 4 bolt diameters mini- a number of overlay constructions. To in joint mum to panel edge develop allowable design values from these test loads the designer must

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TABLE 6 STATIC BOLT LOADS (bolts and nuts finger-tight)(a)(b) Bolt Single Shear Double Shear Overlay Description Bolt Edge 0.015" 0.030" 0.015" 0.030" Face and Back Diameter Distance Deformation Deformation Ultimate Deformation Deformation Ultimate 1/2" PLYWOOD CORE (APA C-D PLUGGED EXPOSURE 1 GROUP 1) 2 oz/sq ft, 1/4" 1" 494 685 2137 943 1349 2325 chopped roving 5/16" 1-1/4" 350 630 2549 1310 1912 2818 SMC(c) 3/8" 1-1/2" 304 590 3158 1448 2172 3227 2.55 oz/sq ft, 1/4" 1" 437 700 2086 814 1362 2234 chopped roving 5/16" 1-1/4" 580 863 2571 1240 1996 3368 SMC(c) 3/8" 1-1/2" 586 958 3265 743 1652 3996 2 oz/sq ft, woven 1/4" 1" 430 756 1907 970 1362 1912 roving, wet layup 5/16" 1-1/4" 492 922 2469 840 1532 2249 (18 oz per yd) 3/8" 1-1/2" 536 995 3151 936 1935 3310 2.67 oz/sq ft, woven 1/4" 1" 460 753 2042 968 1418 2106 roving, wet layup 5/16" 1-1/4" 438 823 2435 1096 1796 2650 (24 oz per yd) 3/8" 1-1/2" 474 818 3008 1050 2014 3129 None (bare plywood) 1/4" 1" 304 491 1177 508 742 967 5/16" 1-1/4" 292 528 1490 722 1002 1427 3/8" 1-1/2" 492 865 1729 738 1043 1514 5/8" PLYWOOD CORE (APA C-D PLUGGED EXPOSURE 1 GROUP 1) 2 oz/sq ft, 1/4" 1" 403 612 2112 760 1432 2391 chopped roving 5/16" 1-1/4" 473 730 2491 1273 1912 2912 SMC(c) 3/8" 1-1/2" 278 574 3099 1086 1988 3475 2.55 oz/sq ft, 1/4" 1" 327 608 2040 1270 1674 2286 chopped roving 5/16" 1-1/4" 566 842 2391 826 1579 2536 SMC(c) 3/8" 1-1/2” 312 692 3112 1410 2222 3274 2 oz/sq ft, woven 1/4" 1" 421 634 2025 974 1416 2194 roving, wet layup 5/16" 1-1/4" 518 829 2430 1271 1750 2379 (18 oz per yd) 3/8" 1-1/2" 419 654 2760 1075 1828 3045 2.67 oz/sq ft, woven 1/4" 1" 502 812 2048 915 1494 2316 roving, wet layup 5/16" 1-1/4" 400 766 2581 1030 1812 3029 (24 oz per yd) 3/8" 1-1/2" 560 956 3234 1170 1999 3108 None (bare plywood) 1/4" 1" 342 500 1195 634 926 1128 5/16" 1-1/4" 259 426 1369 802 1044 1258 3/8" 1-1/2" 271 594 1676 770 1196 1646 3/4" PLYWOOD CORE (APA C-D PLUGGED EXPOSURE 1 GROUP 1) 2 oz/sq ft, 1/4" 1" 388 657 1923 883 1491 2668 chopped roving 5/16" 1-1/4" 404 688 2585 898 1603 2762 SMC(c) 3/8" 1-1/2" 362 825 3606 1138 2252 3765 2.55 oz/sq ft, 1/4" 1" 370 590 2258 892 1535 2516 chopped roving 5/16" 1-1/4" 600 897 2874 1224 1809 3101 SMC(c) 3/8" 1-1/2" 344 662 3441 1021 2074 3750 2 oz/sq ft, woven 1/4" 1" 386 731 2022 612 1396 2193 roving, wet layup 5/16" 1-1/4" 578 1004 2556 752 1438 2508 (18 oz per yd) 3/8" 1-1/2" 486 910 3150 818 1836 3150 2.67 oz/sq ft, woven 1/4" 1" 398 583 1883 796 1273 2011 roving, wet layup 5/16" 1-1/4" 437 640 2391 934 1546 2539 (24 oz per yd) 3/8" 1-1/2" 368 771 3018 1114 1984 2741 None (bare plywood) 1/4" 1" 346 528 1504 848 1151 1377 5/16" 1-1/4" 296 560 2040 710 1220 1772 3/8" 1-1/2" 344 715 2120 1033 1638 2328 (a) Because deformation levels in this table are small in relation to bolt-hole size tolerance of 1/32", loads at these deformation levels show some inconsistency. (b) Bolt test load data for metal overlaid plywood is available from metal overlay fabricators. (c) Sheet Moulding Compound (preformed glass-resin sheet cured and self-adhered to plywood core in a hot press).

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anticipate use conditions. These include Compare the design value from important consideration. While tests required unit stiffness, expected life and the formula to the chart value for the and experience prove that conventional service severity. selected deformation. This step is espe- plywood has adequate strength, the Slip Designing. Since connections affect cially critical for single-shear connec- demand for abuse resistance, longevity unit stiffness, designers must select the tions. Sealant and mastic must be and low down-time dictates the use of suitable value of slip, or relative move- able to tolerate the movement while FRP or metal overlaid panels. ment, between panels and framing. maintaining water-tightness. Stiffness and Strength. These are the Bolts will carry higher allowable loads if Torque. For best joint performance, bolts first properties considered in evaluating somewhat greater slip can be tolerated. should be torqued to recommended any material. They indicate lateral load The reasons for the slip levels listed in levels. Properly torquing a common resistance for side panel use. The EI Table 6 are: Grade-2 NC bolt will improve its static value in Table 7 is a measure of panel 1. A 0.015" slip is a traditional measure- load capacity about 20 percent above stiffness, or deflection resistance. The ment for mechanically fastened wood the finger-tight values in Table 6. (The “Max M” is the maximum moment, a joints. test values in the chart are for finger-tight measure of resistance to breaking under bolts because this condition was easiest load. Stiffness is critical if the panel 2. A 0.030" slip is necessary to bring to duplicate for many laboratory replica- material is to replace both skin and into bearing a bolt off-centered as far as tions.) Clamping a correctly torqued posts. Comparative strength values are possible in a 1/32-inch oversized hole. Grade-5 NC bolt will increase static load less critical for these applications since 3. Ultimate load is the maximum capacity about 30 percent above finger in practice no panel adequate for stiff- load recorded as the bolt and simulated tight. Clamping action with single-shear ness has actually failed in bending framing were forced toward the nearest bolt connections may be limited by the strength. As discussed earlier, other edge of the panel. Tests showed that slip size and strength of the nut bearing properties such as fastener-bearing at ultimate load was much greater against the panel surface. Wetting and strength must also be considered. than the listed values. subsequent drying must be avoided to Table 7 reports results of tests on Bolt Design Values. The following for- maintain the desirable clamping action specimens large enough to accurately mula develops numerical values for of a correctly torqued bolt. (Values for represent sidewall panel behavior. bolted joint design from the ultimate joints subject to moisture absorption are Specimens include panels overlaid with load values in Table 6. about 60 percent of those for dry bolts.) steel, aluminum and reinforced fiber- The formula includes expected Service Condition. The service condition glass by several manufacturers. The test bolt service conditions and effects of a bolted connection influences the method did not include effects of shear of torquing. load level. Service condition comprises deflection, which in actual service may 1) load duration of cycle, 2) ability of reduce effective stiffness by as much as DV = UL t s design to tolerate isolated bolt distress 10 percent. Maximum moment tests where DV = Design Value per bolt and 3) hazard from distress. The service conducted over 5- to 15-minute periods UL = Ultimate Load value from condition factor for use in the equation yielded numerical values which would Table 6 for appropriate panel may vary from 0.50 for a routine design have to be reduced for longer load dura- thickness, overlay type, bolt size, to 0.20 for a highly conservative design. tions. The test values indicate the range single or double shear (The factor used for structural design of of properties available among the variety t = increase for torquing a joint in a building is 0.20.) of overlaid panels. But because of the number of variables involved, these bolt as recommended by bolt Walls manufacturer values cannot be used for exact The choice of wall panels depends on numerical comparison. s = service condition factor adequate strength, stiffness and durabil- Panels used for trailer sides are for equipment design ity. Since they have to do the job for the frequently 3/4-inch all-veneer APA life of the unit, abuse resistance is an C-D Plugged Exposure 1 overlaid on

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TABLE 7 TEST DATA ON STIFFNESS AND STRENGTH OF PLYWOOD OVERLAID WITH FRP, ALUMINUM AND STEEL. Plywood Core Thickness Product Test 1/2 inch 5/8 inch 3/4 inch Description Dates Property Tests Average Range Tests Average Range Tests Average Range SHEET MOULDING COMPOUND OVERLAY 538,800 744,100 EI, lb-in2/ft — — — 4 579,600 to 4 824,300 to 2.00 oz per sq ft Mar 1974 625,500 890,600 chopped roving 8,280 8,320 Max M, lb-in/ft — — — 4 10,040 to 4 9,610 to 12,280 10,750

654,000 831,700 EI, lb-in2/ft — — — 4 710,500 to 4 988,400 to 2.55 oz per sq ft Mar 1974 754,700 1,131,900 chopped roving Max M, lb-in/ft 9,750 10,080 — — — 4 11,400 to 4 11,080 to 12,470 11,840 WOVEN ROVING OVERLAY (WET LAYUP) 2 oz per sq ft glass 258,500 490,300 831,700 (18 oz per sq yd) Jan 1969 EI, lb-in2/ft 2 262,600 to 2 497,600 to 3 950,000 to PS 1 Group 1 thru 266,600 505,500 1,013,300 plywood May 1970 6,070 8,360 12,440 Max M, lb-in/ft 2 6,730 to 2 8,960 to 3 13,160 to 7,390 9,560 13,900

2.67 oz per sq ft glass 563,100 768,000 (24 oz per sq yd) May 1966 EI, lb-in2/ft — — — 3 587,460 to 20 916,500 to PS 1 Group 1 thru 608,300 1,100,400 plywood Mar 1971 10,350 10,100 Max M, lb-in/ft — — — 3 11,240 to 20 12,800 to 12,830 18,350

2.67 oz per sq ft glass 787,000 (24 oz per sq yd) Apr 1969 EI, lb-in2/ft — — — 1 352,000 — 10 913,100 to PS 1 plywood, thru 1,053,300 group undetermined Feb 1971 10,330 Max M, lb-in/ft — — — 1 6,170 — 10 12,160 to 13,250 ALUMINUM SHEET OVERLAY 1,542,800 25-mil aluminum EI, lb-in2/ft 1 713,600 — — — — 2 1,577,800 to PS 1 Group 1 Jan 1970 1,612,700 plywood 11,340 Max M, lb-in/ft 1 5,980 — — — — 2 11,670 to 12,000

2,281,100 40-mil aluminum EI, lb-in2/ft 1 1,004,500 — — — — 2 2,325,800 to PS 1 Group 1 Jan 1970 2,370,600 plywood 15,660 Max M, lb-in/ft 1 9,870 — — — — 2 15,810 to 15,960 GALVANIZED SHEET STEEL OVERLAY 985,200 1,502,100 28- steel Apr 1969 EI, lb-in2/ft 6 1,054,500 to 2 1,539,600 to — — — PS 1 Group 1 thru 1,106,800 1,577,000 plywood Apr 1970 6,990 10,520 Max M, lb-in/ft 6 8,400 to 2 10,990 to — — — 9,720 11,460

1,179,300 1,673,700 26-gauge steel Apr 1970 EI, lb-in2/ft 2 1,180,700 to 2 1,712,800 to — — — PS 1 Group 1 thru 1,182,100 1,752,000 plywood July 1970 7,270 11,950 Max M, lb-in/ft 4 8,760 to 2 12,100 to — — — 9,310 12,240

1,664,100 22-gauge steel EI, lb-in2/ft 4 1,963,900 to — — — — — — PS 1 Group 1 Apr 1969 2,200,800 plywood 11,190 Max M, lb-in/ft 4 12,520 to — — — — — — 13,450

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TABLE 8 FORK-TINE DAMAGE RESISTANCE OF SELECTED FRP PLYWOOD CONSTRUCTIONS Plywood Core Resistance of Composite Thickness Overlay Description – face and back (% of 3/4" bare plywood)

2 oz per sq ft chopped roving SMC 280 2.55 oz per sq ft chopped roving SMC 330 1/2" 2 oz per sq ft (18 oz per yd) woven roving 340 2.67 oz per sq ft (24 oz per yd) woven roving 400 None (bare plywood) 70 2 oz per sq ft chopped roving SMC 340 2.55 oz per sq ft chopped roving SMC 420 5/8" 2 oz per sq ft (18 oz per yd) woven roving 440 2.67 oz per sq ft (24 oz per yd) woven roving 560 None (bare plywood) 80 2 oz per sq ft chopped roving SMC 430 2.55 oz per sq ft chopped roving SMC 500 3/4" 2 oz per sq ft (18 oz per yd) woven roving 540 2.67 oz per sq ft (24 oz per yd) woven roving 670 None (bare plywood) 100 18 gauge U.S. Army Conex Container 300 corrugated steel

both surfaces with 2.67 or 2.55 ounces Tree limb impact resistance can be The tested load level was unusually of glass per foot. Truck sides are measured by the same table because severe – higher than that currently often 5/8-inch-core panels. Varying loads relate to those imposed in the tine required by any state highway combinations of plywood core thick- impact test. The values also indirectly department. Well-manufactured, care- nesses, core species, and glass content measure resistance of various structural fully detailed panels are required for provide panels with the strength, overlaid panels to scuffing during van such severe loadings. For lighter cargos stiffness and abuse resistance essential loading and unloading. Laminators offer and correspondingly reduced front-end for specific design and usage. Manufac- panels with integral scuff strips (a dou- loads, thinner-cored panels are turers can provide information on ble glass application on the lower por- more than adequate. engineering properties and costs of tion of a panel’s inside surface) for van U.S. Department of Transportation available structural overlays. interiors expected to sustain high wear. BMCS Regulation MC-12 requires that Fork-Tine Resistance. Table 8 not only Front-End Strength and Penetration truck and trailer front-end structures illustrates panel resistance to direct fork- Resistance. Testing has confirmed that over six feet high withstand 4/10 of the tine puncture, but also roughly charts all common structural overlaid panels cargo weight, uniformly distributed. For general abuse resistance. Case histories used for truck and trailer front ends a trailer rated at 60,000-pound capacity, have confirmed these laboratory find- easily meet the strength and penetration this force totals 24,000 pounds. ings: structural overlaid plywood panels resistance requirements established by The regulation also stipulates that the survive severe accidents and require the U.S. Bureau of Motor Carrier Safety structure must resist penetration by any only cosmetic surface repairs. in Regulation MC-12. adjacent cargo item when decelerated Since the typical 3/4-inch panels used at 20 feet per second per second. This for trailer front ends survived the test regulation and truck loading practice loading without visible damage, they suggested checking two critical condi- also fulfill the requirements for tions: first, panel resistance to penetra- piggy-back service. tion by a 1-inch bar 40 feet long, decelerated according to MC-12 specifi-

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cation. Thirty-seven-pound resistance bodies because the underframe carries ommended. This edge mechanically satisfies this requirement. Second, a the load. In either case the door may be locks the metal faces together for a 289-pound penetration resistance has made of material cut from the opening. smooth gasket surface. The joint is not been determined to adequately restrain Conventional side-door hinges and waterproof, but it sheds water well a bundle of seven 1-inch pipes locking bars work well with overlaid enough to use for vertical edges. A 40 feet long. plywood. Watertight seals around whole spectrum of rubber and plastic All tested panels were routinely pro- door openings are critical. (See gaskets offers options to locked metal duced by FRP plywood manufacturers. illustrations and comments edges. Gasket detail and door blank size They had either 2.55 oz. per square foot on joints on pages 10-11.) should be carefully considered in designing a good seal. of chopped-roving sheet- com- Rear doors may be any common design, pound, or 2.67 oz. per square foot (24 either hinged or roll-up. These doors are The bottom edge is the most vulnerable oz. per square yard) of woven roving, on usually metal-overlaid plywood panels section of most doors. It’s exposed to plywood core panels of 3/4-inch, 5/8- or Medium Density Overlaid plywood severe wear, and may trap moisture inch, or 1/2-inch thickness. They were with a finish. which can corrode the backs of metal tested in a trailer nose 7 feet wide and 9 surfaces. A high-quality, factory-installed Most rear-door corner posts are tubular feet high (panel size 82 x 100 inches). bottom seal is the best insurance against metal. Door headers are welded to these All withstood 24,000 pounds of uni- this kind of water damage. uprights, occasionally gusseted at each formly distributed load. The 1/2-inch corner with fillet plates for extra rigidity. and 5/8-inch panels, in some cases, Floors Side panels fit into lips on the posts. showed surface resin cracking and Tables 9 and 10 aid selection of required minor cosmetic repair. The 3/4- Door Construction. Designs for correct plywood for floors which must inch panels sustained no visible dam- metal-overlaid plywood doors vary support wheel loads – fork lifts, for age. All displayed ultimate puncture from structural assemblies in intermodal instance. Wheel loadings are normally resistance in excess of 1700 pounds containers (where door tests include much more critical than uniform loads in (load factor equals 46) for a 3/4-inch- direct loadings as high as 25,000 pounds plywood floor design. For example, a diameter rod, and over 5,000 pounds and racking loads of 35,000 pounds) to grain truck has a uniformly loaded floor. (load factor equals 17) for a bundle of relatively light curbside truck doors If the 50 pcf grain were piled 5 feet high, seven 1-inch pipes. which need contribute little to the unit’s the uniform load would equal 250 psf. In structural capabilities. But even for the Table 9 with framing spaced 24 inches o.c., Doors lightest applications, overlaid plywood a Rated Sturd-I-Floor 48 oc (2-4-1) ply- Door Framing. Since most truck, panels are generally specified because of wood floor is recommended. APA 2-4-1 trailer and container side doors are their weather durability and resistance to EXPOSURE 1 (1-1/8 inches thick) has shorter than unit height, part of the damage under punishing use. been used in many truck bodies and overlaid panel remains to span the trailers where forklift wheel loadings were Manufacturers offer several edge opening and carry the load. Trailer not anticipated or were relatively light. treatments for different hardware and bodies may require additional support gasket attachment systems. Where over the opening – usually a bolted edges are exposed to abrasion or metal header plate extending about a impact, a rolled or locked edge is rec- foot beyond the opening. This extra plate isn’t necessary in most truck

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TABLE 9 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-width 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) 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 40/20, 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(d), 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 blocking at panel edges, or install a separate underlayment. (b) A-C Group 1 sanded plywood panels may be substituted for Span Rated Sturd-I-Floor panels (1/2-inch for 16 oc; 5/8-inch for 20 oc; 3/4-inch for 24 oc). (c) Nominal 4-inch wide supports. (d) Group 1 face and back, any species inner plies, sanded or unsanded single layer. (e) All Group 1 or Structural I plywood, sanded or unsanded, single layer.

TABLE 10 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 Load Center-to-Center Support Spacing (in.) Tread per (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 blocking with framing anchors of adequate capacity or similar devices. (b) Provide a wearing surface such as Plyron, polyethylene or a separate layer of plywood, or other hard surface when loads are due to casters, or small, hard wheels. A wearing surface should also be considered for areas where fork-truck traffic is stopping, starting or turning in a tight radius. (c) Use ring- or screw-shank nails with length sufficient to penetrate framing 1-1/2" or panel thickness, whichever is greater. Space nails maximum 4" o.c. at panel edges and 8" o.c. at interior supports.

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Table 10 recommends plywood floor Cargo Restraint Devices Recessed D-rings. According to APA systems for moderate concentrated Logistic Track. With spaced fasteners, tests, a combination of adhesive and loads from forklift traffic. It lists ply- ultimate track attachment strength mechanical fasteners works best with wood thicknesses for various wheel depends largely on the stiffness of the recessed D-rings. Two screws usually loads and spans based on APA tests. track itself. The track must be rigid were not sufficient to develop satisfac- The table shows loads at 65 percent or enough to transmit loads to many tory withdrawal resistance. Adhesives less of the lowest tested distress load. fasteners over a wide area. increase strength, seal panel surfaces Sheet Metal Screws. Sheet metal screws and help hold rings in place. As with Roofs track hardware, the best adhesive results Panel requirements for truck or trailer are the most popular fasteners for logis- tic track because they are easily driven, are obtained with the largest contact roofs vary slightly from side walls since area between hardware and panel. loadings differ. The most severe roof relatively inexpensive and perform well. Fastener Strength. Table 11 illustrates loadings are snow, ice and standing Long sheet metal screws driven at a ultimate loads developed from labora- workmen. Most roofs have been made of 45-degree angle yield significantly better tory test data for several fasteners with APA C-D PLUGGED Exposure 1 Group results than shorter screws driven four load-restraint devices. The tested 1 plywood, 1/2 inch thick, with 2 oz. straight. Most track provides a corner or number of fasteners may not have been per square foot (18 oz. per square yard) angled area through which 45-degree identical to that suggested in the table. glass content FRP on both faces. Users angle holes can be easily drilled. One- The number of fasteners per foot is a report that this roof will permit workmen and-one-quarter-inch-long screws are practical optimum. Reducing the num- on the roof to maintain upper corner easy to handle and develop few ber may be possible where anticipated lighting, shrugs off blows and scrapes stripping problems. loads are less. Increasing the number from tree limbs and sustains less damage Bolts. Bolts are strong, simple and will increase the load, but not from forklift masts. If the roof is struck positive, but outside heads or capped necessarily in proportion to the by a mast raised too high, it’s resilient T-nuts are unsightly and a source of number of added fasteners. enough to spring back to normal. potential leaks. Sealants and noncorro- Note that withdrawal loads over Plywood roof panels require no roof sive heads are essential. An extra rub rail 4,000 pounds and vertical loads over bows. Roof panels are bedded in mastic outside, under bolt heads, increases 8,000 pounds on the belt rails are along the upper side rails, then fastened allowable track loading. beyond the practical load range of the with mechanical connections, usually Gasketing of Fasteners. Gaskets, devices applying the load to the track. bolts. Take care to achieve a secure, neoprene washers, or any other effective These values are only included watertight seal between panel and frame method of achieving a watertight seal at for comparison. and at bolt connections – either with fastener penetrations, both inside and gaskets or neoprene washers under outside of the container, are FRP Plywood boltheads and nuts, or with a high- strongly recommended. Fabrication and Repair performance sealant such as silicone Adhesives. Adhesives supplement, Cutting. Use a sabre for cutting over each bolthead and nut. but do not replace, mechanical fasten- small holes and oddly shaped openings. Sheet aluminum roofs on bows also ings for logistic track. Cleanliness of Use a medium-fine-toothed, hardened- are compatible with vans sided with unpainted track, paint adhesion, ade- steel blade, and, to lengthen blade life, structural overlaid plywood. Such roofs quate contact, proper curing and proper avoid forcing the rate of cut. For longer decrease overall weight slightly, but lack surface preparation must be considered cuts (24 inches or more) use a hand- the superior strength and puncture resis- in designs incorporating adhesives. held power saw with an industrial qual- tance that overlaid plywood roofs deliver. While even a good bond may separate ity, carbide-tipped blade. Expose only as surface resin from fiberglass in a coated much blade as required for teeth gullets panel, flexible-bond adhesives com- to clear the panel and release . bined with proven fastener patterns yield superior performance.

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TABLE 11 LOAD RESTRAINT FASTENING STRENGTH Logistic Track (Belt rail) Recessed Rope Fasteners* Aeroquip Evans Slimline Evans Ring Series E or S-Type Special S-Type Eberhard No. 170

SCREWS 3,300 lbs 2,450 lbs 2,900 lbs 400 lbs 3/4" x No. 14 Sheet metal withdrawal withdrawal withdrawal withdrawal (12 per ft of track 2 per rope ring) 14,000 lbs 10,500 lbs 12,300 lbs — vertical vertical vertical BOLTS – 1/4"-20 with capped T-nut 7,300 lbs 5,500 lbs 6,400 lbs 1,600 lbs (4 per ft of track 2 per rope ring) withdrawal withdrawal withdrawal withdrawal 6,900 lbs 5,200 lbs 6,100 lbs — vertical vertical vertical BLIND INSERTS 5,200 lbs 3,900 lbs 5,100 lbs 620 lbs Helicoil–1/4"-20 5/8" long 2885-4AQ withdrawal withdrawal withdrawal withdrawal or Rosan 1/4"-20 1/2" long RNS 106 SB-8 19,000 lbs 14,000 lbs 16,500 lbs — (12 per ft of track 2 per rope ring) vertical vertical vertical ADHESIVES 1,300 lbs 750 lbs 1,950 lbs 1,060 lbs Flexible 2-part epoxy or withdrawal withdrawal withdrawal withdrawal Flexible 2-part urethane or 10,000 lbs 3,200 lbs 9,000 lbs — Polysulfide rubber-epoxy–2-part vertical vertical vertical Full contact coverage Plus 2 screws per ft for assembly *Panel is 23/32-inch APA C-D Plugged Exposure 1, all plies Group 1, with 18 oz/yd woven roving FRP.

For full-panel cuts, laminators use Repair. In service, FRP plywood resists Metal Overlaid Plywood Fabrication special mounted on heavy steel both abrasion and impact damage. Cutting. Manufacturers of plywood/ frames to assure clean, true cutlines. Experience has shown it to be simple to metal panel products report best results The blades, which have high-quality repair, even after severe accidents. with a hard-edge, 10-tooth, 5/8-inch by carbide tips, may be 14 inches or more Appearance and unit life determine 20 gauge, wavy set, metal-cutting band- in diameter. Where possible, major whether a simple cosmetic patch or saw blade operating at from 300 to panel cutting and trimming should be restoration of strength (as well as sur- 3000 feet per minute. Fair results are done by the panel manufacturer to face) is required. Re-sealing the surface reported with standard assure accurate cuts. is primary, but strength loss always tools on soft metal overlays such as Drilling. Sharp bits operated at high must be evaluated. If glass fibers are cut aluminum, lead and copper. Panels with speed (1500 rpm or more) with moder- or fractured, fiber patches should be metal on one side only should be cut ate feed assure clean holes with maxi- used. Less severe damage can usually with the metal side up. mum bolt bearing. Since a significant be repaired with body putty or resin Drilling. Use carbon-steel twist . amount of bolt strength comes from the and glass cloth. High-speed bits wear longer and cut FRP overlay, a clean-cut hole with a For additional information on repair cleaner. Extension cutters or metal- minimum of torn or chipped glass procedures, consult panel suppliers cutting hole saws can be used for larger- and resin is essential. or write for APA’s Data File: FRP Plywood, diameter cuts. Form G215. Note: Workers cutting or drilling FRP plywood Note: Where practical, cutting, shaping and should wear dust masks. Persons allergic to fine routing of plywood/metal overlays should be done glass dust should protect arms, necks and hands. by the panel manufacturer. Most manufacturers provide cut-to-size service and instructions for working their products with welding, routing, soldering and shaping equipment.

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TRUCK, TRAILER & Truck And Trailer TYPICAL APA TRADEMARKS RAIL CAR LININGS Front-End Structures The Department of Transportation Because of their inherent strength, dura- has established front-end-structure bility and smoothness, conventional requirements as “Protection Against wood structural panels and structural APA Shifting or Falling Cargo” for all THE ENGINEERED overlaid plywood panels provide excel- new cargo-carrying vehicles. WOOD ASSOCIATION lent lining materials for trucks, trailers, DOT Requirements. If the front-end vans and rail cars. Since linings are A-D GROUP 1 structure is less than 6 feet high, the ordinarily subjected to extremely rough DOT says it must withstand a forward EXPOSURE 1 usage, many factors govern material 000 static load equal to 0.5 cargo weight selection. The following recommenda- PS 1-95 distributed over the lower 4 feet of the tions are based on both laboratory test- end wall. If the end wall is higher than ing and broad field experience. 6 feet, it must withstand a forward static They may be used as presented for load equal to 0.4 cargo weight distrib- design development, or regarded APA uted over the entire end structure. The THE ENGINEERED as a basis for comparison with WOOD ASSOCIATION structure must also resist penetration at other lining materials. a deceleration rate of 20 feet per second A-C GROUP 1 Panel Selection per second. EXTERIOR Unless specific or unusual use These requirements are not substantially 000 requirements are anticipated, specify different from industry standards. The PS 1-95 1/4-inch plywood or 3/8-inch APA trade- Truck Trailer Manufacturers Association marked wood structural panels for truck (TTMA) Recommended Practice No. 17 side linings. The most popular thickness suggests for trailers on flat cars (piggy- is 1/4 inch. For front-end linings that back) a load equal to 0.32 to 0.36 cargo APA THE ENGINEERED meet DOT requirements (discussed in weight depending on the number of WOOD ASSOCIATION the following section), specify 1/2-inch axles for the trailer, but has a permanent APA trademarked Group 1 plywood. residual deformation that could inhibit C-D PLUGGED GROUP 1 Heavier bulkheads are usually recom- the function of the unit (assumed to mended in intermodal or piggyback van be 1/2 inch or less). EXPOSURE 1 000 front wall construction, usually 5/8- or Since the DOT Motor Carrier Safety PS 1-95 3/4-inch plywood. For railroad car lin- Regulations apply to all vehicles – not ings use 1/2-inch or 5/8-inch plywood just the van type – the use of plywood for sides, 1 or 1-1/4 inch for ends. as a front bulkhead on other types of strength requirements without structural For smooth interior surfaces, specify trailers and trucks helps meet the change to the trailer, if the boundary APA A-C EXTERIOR plywood. This requirements. Many states have individ- framework is adequate and the plywood panel is intended for use in the most ual requirements for bulkheads or front- well fastened to the framework. severe exposure conditions. For less end structures in trucks. One state, for Recognizing that trailer owners might exacting applications, APA A-D EXPO- example, specifically mentions 3/4-inch wish to strengthen the front ends of SURE 1 or C-D PLUGGED EXPOSURE plywood as a front bulkhead material. their existing trailers to the same level 1 may be used. The trademarks shown Compliance. Experience and tests show required for new equipment, APA tested here are those stamped on plywood that truck or trailer front wall lining of several possible means of achieving this most commonly used as liner material. 1/2-inch APA trademarked plywood of end. These tests demonstrated that Group 1 can meet the front-end equipment built prior to January 1,

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1974 can be retrofitted to meet the Retrofitting: The second stage of loading achieved strength and penetration requirements 1. Applying 1/2-inch plywood over the either a failure condition or a condition by (1) applying 1/2-inch plywood existing nose lining of 1/4-inch plywood in which failure of a portion of the nose over the existing 1/4-inch lining, or will strengthen it adequately to fulfill not readily reparable was imminent. (2) removing the 1/4-inch lining if the DOT requirements. Deflection of the front-end structure was damaged and replacing with measured at six points, stress in the 2. Replacing the nose lining with 1/2-inch plywood lining. aluminum structure at ten points, and 1/2-inch plywood as previously men- movement at joints at eight points. The 1/2-inch plywood, used instead of tioned in New Design (1) can enable it 1/4 inch, may not suffice for all designs to meet the requirements. Results. Table 12 shows the stiffening since not all designs were tested. effect of thicker plywood lining, evi- Test Unit Description. The trailer tested However, the tests show that thicker denced by the higher load capability was a 40-foot-long dry van trailer, linings are beneficial regardless of the at a uniform deflection of 2 inches. 13 feet 4 inches high, as normally structural design of the trailer. Although not shown, the stress of the produced by Timpte, Incorporated. aluminum structure decreased in corre- APA Front-End Testing. A joint test by Although trailers from various manufac- spondence with the increase in load at APA – The Engineered Wood Association turers vary considerably, this one was the 2-inch deflection. All of the and Timpte, Incorporated, Denver, typical of better construction in the maximum loads shown exceed the Colorado, demonstrated clearly that industry. The nose structure had criterion of 0.4 of an assumed cargo plywood truck trailer linings thicker 10-inch radius corners. Nose skin was weight of 55,000 pounds. Thus, either than the 1/4-inch lining normally used 0.050-inch aluminum applied over the use of 1/2-inch APA trademarked contributed substantially to the stiffness 1-3/4-inch Z posts. Six Z posts were A-C plywood over the Z posts, or the of the front-end structure and the unit’s used in the nose structure. Both the addition of 1/2-inch plywood over an ability to meet DOT strength require- skin and posts bear against the inside existing 1/4-inch lining meets the DOT ments. The test program used the nor- surface of the upper nose rail and the requirements for the test trailer. For vans mal nose structure of the dry van trailer, coupler assembly. modifying only the inside nose lining with greater cargo capacity rating, Test Procedure. Load was applied to the and its fastenings. thicker plywood can be used or the inside of the nose assembly through 16 adhesive bonding of the plywood to the General conclusions are: uniformly spaced hydraulic jacks bear- posts can achieve higher loadings. New Designs: ing against 1-foot-square plywood Extending the nose lining plywood into 1. The DOT strength requirement was load-distributing pads to simulate the curved corner and using aluminum fulfilled in the tests with 1/2-inch cargo bearing uniformly against flashing helps hold the curved shape. plywood as the nose lining. the front structure. (See details page 23.) The first stage of loading achieved 2. Thicker and stiffer plywood linings Panel Installation approximately 2 inches of deflection at reduce the stress in the aluminum struc- Orientation and Framing. Wood the midpoint of the center post of the ture and skin for a given load pressing structural panels are strongest, and front-end structure. This condition against the inside. possess the greatest deflection resis- would cause little, if any, permanent set 3. Increasing the nose lining thickness tance, when installed with the in the front-end structure when to 1/2 inch substantially stiffens the long dimension or strength axis unloaded. Previous tests with the front end so that the full perimeter of perpendicular to framing. Z posts had established this point as the nose restrains the load. closely approximating the yield point Depending on panel orientation and for the framework. use, edge blocking may be necessary. Panels installed horizontally (strong axis perpendicular to wall posts) should be

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TABLE 12 TEST RESULTS Test for 2-in. DETAILS A, B & C AS NOTED Trailer Deflection Test for Maximum Loading Lining Detail Load Load Why Deflection No lining, Detail A (lb) (lb) Terminated (in.) 1-3/4" Z-post in nose 1/4" lining, Detail B None A 7,000 —— — 1/2" plywood over 1/4-in. A-C plywood 1/4" lining Detail C 1/4-in. nylon B 7,767* —— — Alum. flashing normally fasteners 12 in. oc in corner was omitted in Details A, B & C. 1/2-in. A-C plywood 10" radius corner over the construction C 11,765* 22,200 skin corner tore 3.70 1/4" plywood side linings above 1/4-in. deck screws 6 in. oc 1/2-in. A-C plywood stopped to DETAILS D, E, & F 1/4-in. deck D 11,082* 27,973 preserve upper 3.35 AS NOTED screws 10 in. oc nose rail 3/4" A-C plywood 3/4-in. A-C plywood stopped to Details E & F. Adhesive 1/4-in. deck E 12,503* 31,225 preserve upper 3.50 added Detail F only. screws 10 in. oc nose rail 1/2" A-C plywood lining, Detail D 3/4-in. A-C plywood stopped to Screws 10 in. oc 0.050 in. alum. flashing F 15,385* 31,524 preserve upper 3.51 and adhesive 1/4" plywood lining; nose rail bonded to posts 1/4" nylon fasteners *Interpolated from readings for deflections ranging from 2.04 in. to 2.08 in. Trailer side skin

blocked to ensure a smooth joint and nontoxic sealers are permitted in equip- other loads are imposed on the lining. permit tight sealing of insulated walls. ment used to haul foodstuffs.) A large fastener shank will sustain the Panels installed vertically (strong axis Overlaid or coated plywood products highest shear load. Front-end strength- parallel to wall posts) should be blocked such as High Density Overlay minimize ening sometimes requires more fasteners along lower edges to reduce wear due to joints and provide a positive vapor bar- than simple attachment. handling-equipment scuffing. Metal or rier. Fiberglass-reinforced-plastic ply- Contour – the heads of fasteners should plywood scuff plates that can be wood panels are available in sizes large be flush – or nearly flush – with the easily replaced as wear occurs enough to cover the entire wall of a lining to minimize snagging and cargo are also recommended. 45-foot van. Such panels are particularly damage. A large-diameter, low-profile Panels should be spaced 1/8 inch at all useful where frequent cleaning is head fulfills this requirement. joints to allow for possible expansion. required and where a complete Removal – fasteners should be easily Joint Treatment and Sealing. In moisture seal is mandatory. removable for repair or panel replace- refrigerated equipment, moisture exclu- Fastener Selection. Many kinds of ment. Some fasteners must be sheared sion is essential to preserve materials fasteners are suitable for securing panel or ground down for removal at substan- and promote thermal efficiency linings to trailers or rail cars. Fastener tial cost in labor and materials. of insulation. selection depends upon these Compatibility – fasteners should be Joint moldings and sealers are always basic factors: compatible with intended loads and use recommended for refrigerated vans with Strength – strength sufficient to resist conditions. For example, plastic or plywood linings. Plywood linings should withdrawal and lateral loads is required. stainless steel fasteners may be required also be sealed to prevent moisture Such loads are not usually severe, but for certain kinds of food cargo. Fasteners migration through panels. Dip-sealing can increase dramatically if cargo that resist moisture may be required ensures that both panel sides and edges restraint devices, hooks, shelving or where high environmental moisture are thoroughly sealed. (Only approved will be encountered.

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TABLE 13 SHEET METAL SCREWS: PLYWOOD-TO-METAL CONNECTIONS(a) Ultimate Lateral Load (lb)(b) Plywood Framing Thickness Screw Size 1/4"-20 Self (in.) #8 #10 #12 #14 Tapping Screw

1/4 330 360 390 410 590 0.080" 1/2 630 850* 860 920 970 Aluminum 3/4 910* 930* 1250 1330 1440

0.078" 1/4 360 380 400 410 650 Galvanized Steel 1/2 700* 890* 900 920 970 (14 gauge) 3/4 700* 950* 1300* 1390* 1500 (a) Plywood was A-C EXT grade (all plies Group 1), face grain parallel to load. (b) Loads denoted by an asterisk (*) were limited by screw-to-framing strength; others were limited by plywood strength.

TABLE 14 SHEET METAL SCREWS: PLYWOOD-TO-METAL CONNECTIONS(a) Ultimate Withdrawal Load (lb)(b) Plywood Framing Thickness Screw Size 1/4"-20 Self (in.) #8 #10 #12 #14 Tapping Screw

1/4 130 150 170 180 220 0.080" Aluminum 1/2 350 470 500 520 500 3/4 660 680 790 850* 790*

0.078" 1/4 130 150 170 180 220 Galvanized Steel 1/2 350 470 500 520 500 (14 gauge) 3/4 660 680 800 900 850 (a) Plywood was A-C EXT grade (all plies Group 1). (b) Loads denoted by an asterisk (*) were limited by screw-to-framing strength; others were limited by plywood strength.

TABLE 15 FASTENER EQUIVALENCY 1/4-in. A-C Plywood Lining

Body Diameter Head Diameter Equivalent Sheet Metal Screw Fastener (in.) (in.) Withdrawal Shear

Blind rivet 3/16 3/8 #12 #8 Blind rivet 3/16 5/8 #14 #8 Pin drive rivet 3/16 3/8 #12 #10 Nylon spread rivet 1/4 1/2 #8 #8 Self drill screw #10-32 1/2" wafer #14 #10

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TABLE 16 WOOD AND SHEET METAL SCREWS: METAL-TO-PLYWOOD CONNECTIONS(a)(b)

Depth of Average Ultimate Withdrawal Load (lb) Threaded Screw Size Penetration (in.) #6 #8 #10 #12 #14 #16

3/8 150 180 205 — — — 1/2 200 240 275 315 350 — 0.25" 5/8 250 295 345 390 440 — 3/4 300 355 415 470 525 — 1 — — — 625 700 775 1-1/8 — — — 705 790 875 2-1/4 ————1580 — (a) Plywood APA RATED SHEATHING Exposure 1 marked “PS 1” (all plies Group 1). (b) Average ultimate withdrawal loads from oriented strand board are 60% of the values shown for all-Group 1 plywood. NOTE: Table 16 presents ultimate withdrawal loads for wood and sheet metal screws in wood structural panel-and-metal joints, based on analysis of test results. Wood screws have a tapered shank and are threaded for only two-thirds of their length. Sheet metal screws typically have higher ultimate loads than wood screws in the smaller gauges because of their uniform shank diameter and full-length thread. The difference is not as apparent in the larger gauges and lengths because the taper is not as significant. For wood screws, values shown in Table 16 are based on 1/4-inch protrusion of the wood screw from the back of the panel. This was to assure measurable length of thread embedment in the wood since the tip of the tapered wood screw may be smaller than the pilot hole. This was not a factor for sheet metal screws due to their uniform shanks.

Fastener Use. Tables 13 and 14 provide without loosening; (2) insulation – Cargo Restraint Devices ultimate shear and withdrawal loads for nonmetallic fasteners perform best; Cargo must be restrained within a sheet metal screws for recommended (3) corrosion – stainless, nonmetallic, or truck or rail car to prevent damage to plywood thicknesses fastened to framing. well-plated fasteners are recommended; the cargo itself and the transport unit. Similar information on nails, staples and and (4) ease of use – simple one-step Attaching restraints directly to the bolts may be found under “Fasteners,” and easy-to-remove. For most linings, framework is most desirable, especially page 31. The ultimate test loads repre- the fastener strength is not a limiting with thin liner panels, but fastening to sent maximum loads carried by the fas- factor. Linings seldom apply a critical the wall and lining may be necessary in tener under test at actual failure. Each load to fasteners. Table 15 presents some cases. Table 16 lists ultimate with- load must be reduced by a factor fastener equivalency. drawal loads for wood and sheet metal appropriate to the intended use. A load Fastener spacing of 6 inches o.c. at screws in plywood-and-metal joints. factor of 2 is appropriate for some appli- edges and 12 inches o.c. at intermediate See Table 11 for ultimate loads for cations in transportation; whereas load supports should be a minimum, even if cargo restraint devices. Since these factors of around 4 or 5 are often used for the loading is not critical. These spac- values are based upon the strength permanent applications. Load factors ings aid in holding panels flat and solid. characteristics of FRP plywood, some- should take into account duration of Rail car linings may be fastened to wood what lower values will be achieved with stress, moisture content, variability sleepers or direct to metal frame. Most conventional 3/4-inch plywood. For among panels and between species. frequently, linings are nailed to wood detailed discussion of ultimate loads (Values shown are based on physical sleepers with pneumatically-driven nails. for cargo restraint device fasteners, see properties of Douglas-.) Scarf-jointed 10' x 30' panels are avail- page 19 of this manual. In addition to the strength of fasteners able to line half a rail car side with shown, consideration may be required one piece. This minimizes joints for: (1) vibration and the ability to flex and simplifies installation.

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RECREATIONAL cations subject to severe moisture. panels among the most useful of glued VEHICLES AND BUSES These single-floor panels possess high plywood components. Stressed-skin concentrated- and impact-load resis- panels typically consist of one or two RV manufacturers use APA trademarked tance. UNDERLAYMENT is recom- plywood skins glued parallel to lumber structural panels in motorhomes and mended for application over structural stringers with rigid structural adhesives. mini-homes, in travel trailers, fifth-wheel subflooring – EXPOSURE 1 for normal The panel functions as a single struc- trailers and tent trailers, in vans, pickup service, C-C PLUGGED EXTERIOR for tural unit with greater load-carrying campers and all kinds of special-order, applications where severe moisture may capacity than its individual members custom-made and converted units. be present. These touch-sanded panels would have if installed separately. The Typical applications include floors, cabi- provide a smooth surface for application plywood skins take most of the bending nets, bed boards, wall linings, counter of finish flooring. “Sanded face” is a stress while the lumber stringers con- tops, seats, shelving, roof decking, doors special notation for panels intended for tribute shear strength. With both top and miscellaneous bracing and mount- use under thin resilient flooring. and bottom skins and insulative filling, ing. Panel strength, stiffness and impact C-D PLUGGED EXPOSURE 1 panels the stressed-skin panel also provides resistance contribute to safety while the are used for bed bottoms and other excellent thermal values. light weight cuts fuel consumption. structural applications where appear- Like stressed-skin panels, plywood Recreational vehicle design, of course, ance is not important. This grade is sandwich panels offer stiffness, high varies widely throughout the industry. particularly popular for RV flooring, but load-handling capability, light weight This section, therefore, does not suggest lacks the puncture resistance of STURD- and fast, panelized construction. specific designs, but presents useful I-FLOOR and Underlayment grades. Sandwich panels are prefabricated by information for designing and working C-C PLUGGED EXTERIOR panels are sandwiching an insulating core material with structural panels. It includes data ideal for tile backing and other severe such as polystyrene or polyurethane about panel properties of special rele- moisture applications. foam, or a paper honeycomb, between vance to RV and bus manufacturers, A-D EXPOSURE 1 and A-C EXTERIOR skins of plywood. Cores and skins are and about framing and fastening are sanded grades for applications where bonded with rigid structural adhesives structural panels. the appearance of only one side is or direct adhesion of foam to the faces. Panel Selection important – built-ins, cabinets, shelving, For complete information on plywood Conventional Structural Panels. countertops, paneling, and front-end stressed-skin and sandwich panels, write Several grades of structural panels are and sidewall linings. B-D EXPOSURE 1 APA for the following publications: recommended for specific RV applica- and B-C EXTERIOR are utility sanded • Plywood Design Specification, tions. APA RATED SHEATHING EXPO- panels with one smooth side used for Form Y510 SURE 1 is particularly well suited for backing, built-ins and bed bottoms. • Plywood Design Specification, subflooring and wall and roof sheathing. MEDIUM DENSITY OVERLAY (MDO) Supplement 3 – Design and Fabrication of APA RATED SHEATHING EXTERIOR panels provide an ideal base for paint Plywood Stressed-Skin Panels, Form U813 fulfills the same function under high and exhibit excellent abrasion resistance moisture conditions. APA STRUC- in such applications as cabinets • Plywood Design Specification, TURAL I RATED SHEATHING EXPO- and built-ins. Supplement 4 – Design and Fabrication of Plywood Sandwich Panels, Form U814 SURE 1 and EXTERIOR are unsanded These are the basic panels and structural grades for engineered applica- applications for RV fabrication, although Structural Overlays. Fiberglass- tions where strength is of maximum special panels and panel systems are reinforced-plastic (FRP) plywood and importance, such as bracing, gusset available for other purposes. plywood with aluminum or other metal plates and mountings. overlays can add great strength and Stressed-Skin And Sandwich Panels. impact resistance in applications where, APA RATED STURD-I-FLOOR is High strength-to-weight ratios and as in walls and roofs, structural integrity recommended for floors – EXPOSURE 1 efficient use of materials make PS 1 is especially critical. for normal service, EXTERIOR for appli- plywood stressed-skin floor and wall

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TABLE 17 RECREATIONAL VEHICLE SINGLE-FLOOR RECOMMENDATIONS Maximum Support Spacing (in.) 12 16 24 APA Panel Grade Long Long Long Long Long Long Dimension Dimension Dimension Dimension Dimension Dimension Across Along Across Along Across Along Supports Supports Supports Supports Supports Supports Span Rating(a) APA STURD-I-FLOOR EXP 1 16 oc 16 oc(b) 16 oc 20 oc(b) 20 oc 24 oc(b) APA STURD-I-FLOOR EXT (a) Sturd-I-Floor is manufactured 19/32" or thicker as required by Span Rating. See APA’s Product Guide: Grades & Specifications, Form J20. For 12" oc support spacing, 1/2" UNDERLAYMENT grade plywood may be substituted. (b) Specify 5-ply, 5-layer construction only. Note: The recommendations in Tables 17 and 18 for floors have been formulated specifically for recreational vehicle applications. The maximum spans pre- sented for other applications, however, are based on the use of structural panels in residential construction. Because the duration of loads, vehicle life expectancy and code requirements are less demanding in RV than in residential construction, thinner panels than those recommended in the tables are frequently and successfully used. For additional assistance in determining appropriate thickness and spans, contact the APA field representative in your area or the Association’s Technical Services Division.

These panels are discussed earlier APA RATED STURD-I-FLOOR panels specified by Span Rating. For even in this manual under Panel Types and may be used in combined subfloor- greater floor stiffness, gluing the panels Properties. For more extensive informa- underlayment construction. STURD-I- to framing is recommended. tion on FRP and metal overlaid FLOOR is available with either square Table 18 gives recommended panel and plywood, contact APA – The Engineered edges or precisely engineered tongue- support spacing combinations for panel Wood Association. and- joints that eliminate the subflooring beneath a separate underlay- Special Overlays. Some APA member need for blocking or other edge support. ment. Recommended subflooring grades mills produce high-performance lami- Panels can be ordered with either are APA RATED SHEATHING EXPO- nated panels with vinyl, polyester resin EXTERIOR or EXPOSURE 1 durability SURE 1, APA RATED SHEATHING or other abrasion-resistant woodgrain classification. For applications subject to EXTERIOR, APA STRUCTURAL I overlays that are ideal for cabinets, parti- continuous moisture or high humidity, RATED SHEATHING EXPOSURE 1 tions, and other interior finish specify only EXTERIOR panels. and APA STRUCTURAL I RATED applications. These panels combine the Although some RV manufacturers have SHEATHING EXTERIOR. successfully used APA A-D or C-D strength of a plywood substrate with an Some manufacturers also use sandwich PLUGGED panels, RATED STURD-I- attractive, durable, easy-to-clean surface. or stressed-skin panel assemblies. (See FLOOR panels are recommended Check with your supplier for available Stressed-Skin and Sandwich Panels, because of their greater puncture surface patterns and panel thicknesses. page 26, for additional information.) resistance. This may be less critical Floors under padded carpet. Vehicle floors sometimes can be exposed to a demanding environment. The leading application of structural Table 17 gives recommended support In these instances, excessive moisture panels in recreational vehicles and buses spacings for RATED STURD-I-FLOOR. may become a problem, especially at today is floors. Combined subfloor- Panels may be placed either across or panel edges and at fastener penetra- underlayment (single-floor) construction along supports. These recommenda- tions. Untreated wood structural panels, provides economy, ease of application, tions were developed specifically for including Marine Grade plywood, might stiffness and resilience. Appropriate recreational vehicle applications and decay if conditions are right for decay grades touch-sanded or sanded during vary somewhat from those normally organisms to flourish. One solution is to manufacture offer a smooth surface for allowed in residential construction. use preservative-treated plywood, expe- direct application of nonstructural Note that STURD-I-FLOOR panels are finish flooring. cially for floor repairs where decay of untreated panels has occurred.

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TABLE 18 RECREATIONAL VEHICLE SUBFLOORING RECOMMENDATIONS Maximum Support Spacing (in.) 12 16 24 APA Panel Grade Long Long Long Long Long Long Dimension Dimension Dimension Dimension Dimension Dimension Across Along Across Along Across Along Supports Supports Supports Supports Supports Supports Span Rating APA RATED SHEATHING EXP 1 APA RATED SHEATHING EXT APA STRUCTURAL I 32/16 32/16 32/16 40/20 40/20 48/24 RATED SHEATHING EXP 1 APA STRUCTURAL I RATED SHEATHING EXT Note: The recommendations in Tables 17 and 18 for floors have been formulated specifically for recreational vehicle applications. The maximum spans pre- sented for other applications, however, are based on the use of structural panels in residential construction. Because the duration of loads, vehicle life expectancy and code requirements are less demanding in RV than in residential construction, thinner panels than those recommended in the tables are frequently and successfully used. For additional assistance in determining appropriate thickness and spans, contact the APA field representative in your area or the Association’s Technical Services Division.

Preservative-treated plywood is weight, fuel economy need not be impregnated with preservatives by a sacrificed to satisfy structural criteria. TABLE 19 pressure process. The resulting deep Table 19 gives thickness and support RECREATIONAL VEHICLE penetration of preservative treatment WALL SHEATHING spacing recommendations for panel wall RECOMMENDATIONS provides protection against decay. The sheathing. Panels may be installed either Maximum plywood should be marked APA Series Panel Support vertically or horizontally, although verti- Span Rating Spacing (in.) V-600 for Exposure 1 panels, and APA cal application generally provides 12/0, 16/0, 20/0 16 series V-611 for Exterior panels, which greater racking resistance. 24/0, 24/16, 32/16 24 signify panels suitable for preservative A-C EXTERIOR and A-D EXPOSURE 1 treatment. The plywood should be are the most commonly used grades for treated in accordance with American Roofs front-end and sidewall linings. Wood Preservers Association Standard The frequent use of RV roofs as storage C9 (Plywood-Preservative Treatment by Some RV manufacturers have used spaces and sun and observation decks Pressure Process), and, for waterborne sandwich wall panels with painted, demands a stiff decking or reinforcing preservatives, redried to 18% moisture papered or vinyl-covered plywood as the material that will distribute loads with- content or less. For further information, interior “skin.” APA Decorative and 303 out bending, denting or cracking. APA refer to APA Product Guide: Preservative- Siding panels – both available in a vari- structural panels are the solution. Treated Plywood (Q220). ety of surface textures – provide unique Roof construction with APA panels also and attractive interior walls and parti- offers excellent impact resistance and Walls tions. Several special panels with vinyl diaphragm characteristics for improved Requirements of the Department of or grain-print overlays are also available. Transportation and other regulatory occupant safety. And for ceilings that For even greater strength and durability, agencies make the structural capabilities contribute strength, good looks and full wall panels overlaid with a structural of RV wall systems a major design con- improved sound control, APA Decora- material such as aluminum or fiberglass- sideration. Panel wall sheathing, corner tive and 303 Siding panels are reinforced plastic are available. These bracing and front-end and sidewall excellent choices. panels can reduce the framing required linings deliver shear strength, rigidity The thickness and span recommen- since the strength of the composite and impact resistance for improved dations for panel roof sheathing in panel is greater than that of the core safety and durability. Yet because struc- Table 20 apply to APA RATED alone. (See page 26.) tural panels are also relatively light

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TABLE 20 RECOMMENDED UNIFORM LIVE LOADS FOR APA PANEL ROOF SHEATHING WITH LONG DIMENSION PERPENDICULAR TO SUPPORTS(e) (APA RATED SHEATHING and APA STRUCTURAL I RATED SHEATHING) Minimum Maximum Span (in.) Allowable Live Loads (psf)(c) Panel 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 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 32 28 325 180 120 70 30 ——— 40/20 19/32 40 32 — 305 205 130 60 30 —— 48/24 23/32 48 36 — 410 280 175 95 45 35 — 48 oc(d) 1-3/32 60 48 — — — 290 160 100 65 40 (a) Tongue-and-groove edges, panel edge clips (one between each support, except two between supports 48 inches on center), lumber blocking, or other. (b) 24 inches for 15/32-inch and 1/2-inch panels. (c) 10 psf dead load assumed. (d) Span Rating applies to APA RATED STURD-I-FLOOR “2-4-1”. (e) Applies to panels 24 inches or wider.

SHEATHING EXPOSURE 1, APA UNDERLAYMENT panels spaced Normal-duration working loads are RATED SHEATHING EXTERIOR, APA 1/32 inch at edges and ends, to allow for appropriate in most designs. However, STRUCTURAL I RATED SHEATHING any possible expansion due to moisture. for certain connections it may also be EXPOSURE 1 and APA STRUCTURAL I necessary to check the ultimate strength RATED SHEATHING EXTERIOR. Fasteners during short-duration crash situations. The following fastener data for The floor-to-chassis connections restrict Framing plywood was developed specifically body movement which could possibly APA panels are generally strongest and for recreational vehicle design in con- puncture fuel tanks or sever fuel lines. have the greatest resistance to deflection formance with crash-resistant require- Table 21, which may be applied to when installed with the strong axis ments, as well as for applications not crash-related design, presents ultimate (panel long dimension) perpendicular to necessarily related to crash conditions. loads and joint slips for three floor-to- (across) framing members. Depending on The values presented are all ultimate chassis connections under four angles of orientation and use, it may be necessary loads and may be applied only to the applied load. The angles of loading to block panel edges. Refer to the span joint construction described. relate to the barrier crashes of the RVIA tables in the previous sections for panel Floor-To-Chassis Connections. Federal test vehicles. The largest ultimate load thickness and support spacing recom- Motor Vehicle Safety Standard 301 values occur in an all-shear (0°) loading mendations. Since the span tables for requires that motor homes under situation. Ultimate loads during uplift of sheathing grades, except subflooring, are 10,000 pounds in weight be capable of the floor connections (90°) may depend based on the use of structural panels in withstanding a 30 mph barrier crash upon design of lumber framing as residential construction, some variation – with a fuel leakage of not more than one well as fasteners. thinner panels or greater support spac- ounce per minute. The Recreational To develop normal-duration design ings – may be allowable in recreational Vehicle Industry Association (RVIA), in values from the ultimate loads presented vehicle applications. In multi-panel conjunction with chassis manufacturers, in Table 21, designers must consider construction, sheathing and STURD-I- has developed data on the direction anticipated end-use conditions. FLOOR panels should be spaced of the forces present during 1/8 inch at edges and ends, and numerous test crashes.

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The service condition of the bolt suitable for specific conditions. The FIGURE 11 connection will influence the level of load-slip relationships presented in LOAD-SLIP RELATIONSHIPS loading. Service condition considera- Table 21 may be assumed proportional FOR FLOOR-TO-CHASSIS tions include 1) load duration or cycle for lower loads. (See Figure 11.) Based CONNECTIONS, LOADED IN SHEAR of loading, 2) ability of design to tolerate upon design slip requirements, design- isolated bolt distress, 3) hazard from ers can therefore estimate a design load distress and 4) moisture content. The and the number of connectors service-condition load factor used by required for the floor units. the designer may vary from 2.0 for For example, if the designer were plan- routine design to 5.0 for a conservative ning to use a 3/8-inch-diameter carriage

Load (lbs) Load design. The latter value may be appro- bolt with a maximum joint slip of priate and is commonly used for (Example) 0.5 inch per fastener, what would be the

1000 2000 3000 4000 structural applications in buildings. maximum load per fastener? Referring to Suitable design values also involve Figure 11, the corresponding load at 0 0.25 0.50 0.75 1.00 estimating the ultimate stiffness 0.5-inch slip is 1,750 pounds. This load Joint Slip (in.) required of the flooring and any special also corresponds to a load factor of 3/8" diameter elevator bolt in-service requirements. Joint slip will 3700/1750, or 2.11. (See Table 21.). 3/8" diameter carriage bolt affect the stiffness of the floor unit. For best joint performance, bolts should with 1-1/4" diameter washer Designers are responsible for selecting be torqued to the levels recommended value of slip, or relative joint movement, 3/8" diameter carriage bolt

TABLE 21 ULTIMATE LOADS – FLOOR-TO-CHASSIS ANCHORAGE Bolts pass through 1/2-inch Group 1 APA plywood and 2x2 framing to 1/4-inch-thick steel. Bolt torque is 150 in-lbs. Bolt threads bear on steel. Angle of Applied Load 0° 15° 30° 90° 3/8-inch-diameter Ultimate 3700 3450 3500 3250 carriage bolt Load(b) (lbs) avg. tension yield Slip @ 1.1 1.0 1.1 1.0 strength = 4226 lbs(a) Ultimate Load (in.) 3/8-inch-diameter Ultimate 3950 3700 3750 Load carriage bolt with Load(b) depends 1-1/4-inch washer (lbs) upon span avg. tension yield Slip @ 0.9 0.8 0.9 length of lumber Angle of strength = 4226 lbs Ultimate applied load Load (in.) framing. 3/8-inch-diameter Ultimate 4150 3900 4000 elevator bolt with Load(b) Load 1-5/16-inch (lbs) depends head diameter upon span length of avg. tension yield Slip @ 0.8 0.8 0.7 lumber strength = 5067 lbs Ultimate framing. Load (in.) (a) Bolts were tested in tension in accordance with ASTM A-370 at a loading speed of 0.1 inches per minute. (b) Static ultimate bolt loads, recorded at a loading speed of 0.1 inches per minute, have been increased by 10% to reflect crash related design.

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by the manufacturer. The joints shown FASTENERS working load may be increased by in Table 21 are based on a torque level 10 percent. Normal load duration of 150 inch-pounds. The integrity of a structure is frequently contemplates fully stressing the connec- dependent upon the connections tion for approximately 10 years, either Adhesives between its component elements. For continuously or cumulatively. A wide variety of adhesives are available maximum strength and stability, each For laterally loaded screws, a working for use in conjunction with nails or joint requires design adapted to fastener load of normal duration may be approxi- staples in the fabrication of wood struc- type and to the strength properties of mated by dividing the tabulated tural panel-and-lumber components and individual structural members. Included ultimate load by 5 or 6. For practically assemblies. These include rigid struc- in the following tables are ultimate all laterally loaded screw connections tural, semi-structural, modified poly- lateral and withdrawal loads for shown, the normal-duration working vinylacetate (PVA) and hot-melt various plywood joints. load will correspond to a joint slip of adhesives. The best choice will depend These values are based upon tests less than 0.01 inch. on both the end-use application and conducted by APA – The Engineered For nails and staples in withdrawal, a production needs. Room-temperature- Wood Association. setting adhesives are usually best for working load of about one-sixth of the fabricating components and assemblies Estimating Allowable Design Loads ultimate load has traditionally been used for recreational vehicle applications. To It is the responsibility of the designer for long-duration loads. For normal load ensure best performance, specify an to select a working load suitable for each duration, the long-term working load adhesive that conforms to a performance particular application. For screws in may be increased 10 percent. standard fitting the end use. withdrawal, a working load of about one- For laterally loaded nails and staples, a sixth of the ultimate load has traditionally working load of normal duration may be been used for long-duration loads. For approximated by dividing the tabulated normal load duration, the long-term ultimate load by 5.

TABLE 22 WOOD SCREWS: METAL-TO-PLYWOOD CONNECTIONS Depth of Screw Average Ultimate Penetration Size Lateral Load 8 ga. 950 lbs 1-1/4" thread penetration* 1-1/4" 12 ga. 1310 lbs *Penetration is into underlying spruce framing.

TABLE 23 SCREWS: METAL-TO-PLYWOOD CONNECTIONS(a) Depth of Ultimate Lateral Load (lb)(b) Threaded Penetration Wood Screws Sheet Metal Screws (in.) #8 #10 #12 #8 #10 #12 1/2 415 (500) 590 465 (565) 670 1" typical 5/8 — — — 500 (600) 705 3/4 — — — 590 (655) 715 (a) Plywood was APA RATED SHEATHING (all plies Group 1), face grain parallel to load. Side plate was 3/16"-thick steel. (b) Values in parentheses are estimates based on other tests. Wood Screw Sheet Metal Screw

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TABLE 24 NAILS: ULTIMATE LATERAL LOADS IN LUMBER (lb per ) Plywood Thickness Common Nail Size (in.) 6d 8d 10d 16d 3/8" 5/16 275 305 — — 3/8 275 340 — — 1/2 — 350 425 — 5/8 — 350 425 445 3/4 — — 410 445

TABLE 25 NAILS: DIRECT WITHDRAWAL FROM LUMBER FRAMING (lb per inch penetration into side grain of member holding point) Framing Species and Common Nail Size Specific Gravity 6d 8d 10d 16d Douglas-fir 160 185 205 230 SG – 0.51 W. Hemlock 135 160 180 195 SG – 0.48 E. Hemlock 115 135 155 165 SG – 0.45 Spruce – – Fir 100 135 155 165 SG – 0.42 E. White Pine 55 60 70 70 G – 0.34

TABLE 26 STAPLES: ULTIMATE LOADS(a)(b) (lb per ) Penetration into Lumber Lateral Withdrawal (in.) Load Load 3/4 160 100 1 180 150 1-1/4 200 200 1-1/2 220 — (a) Values are for 3/8-in. and thicker plywood, 16 gauge galvanized staples with 7/16-in. crown, driven into Douglas-fir lumber. (b) Some plastic-coated staples may provide higher values.

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TABLE 27 FASTENERS INTO PLYWOOD PANEL EDGE (Fasteners through 1/4" Group 1 plywood into edge of 3/4" plywood with Group 2 inner plies.) Average Ultimate Load (lb per fastener) Fastener Description Withdrawal Lateral Loading Loading Staple 1-1/8" long, 7/16" crown, 90 110 16 gauge (0.0625") 1-1/4" long, 7/16" crown, 105 110 16 gauge (0.0625") 105 110 1-1/2" long, 7/16" crown, 105 110 16 gauge (0.0625") Nail 1-1/4" ring shank, 13 gauge 110 90 (0.086"), 0.205" head – clipped T-Nail 1-1/2" smooth, 12-1/2 gauge 130 80 (0.097") T head – 5/16" wide NOTE: Fastening into plywood panel edges will not provide nearly the withdrawal or lateral loading capabilities of fastening into panel faces and is not normally recommended. For some purposes, however, edge fastening may be both necessary and workable.

TABLE 28 WOOD SCREWS: PLYWOOD-TO-PLYWOOD EDGE CONNECTIONS(a)

Depth of (b) (b) Threaded Ultimate Lateral Load (lb) Ultimate Withdrawal Load (lb) Penetration (in.) #8 #10 #12 #8 #10 #12 1 180 (185) 195 360 (405) 450 1-1/2 180 (185) 195 410 (455) 500 (a) Plywood receiving screw thread was 3/4"-thick APA RATED SHEATHING Exposure 1 marked “PS 1” (Group 2 inner plies). (b) Values in parentheses are estimates based on other tests.

For bolts, a normal-duration working tional 20 percent, a corresponding joint of the wood (i.e., not the strength of the load may be approximated by dividing slip of less than 0.015 inch can be metal fastener) determines the load the tabulated ultimate load by a factor of expected in most cases. Loads at this capacity. Adjustment of design values 5. For practically all bolted connections latter slip value have traditionally been for varying duration and combinations shown, this working load will corre- used as the maximum allowable lateral of load, as well as for wet conditions, spond to a joint slip of less than load for nailed joint design. should be in accordance with the 0.030 inch. The slip value of 0.030 inch Adjustments for shorter or longer current AF&PA National Design brings the bolt into maximum bearing duration of load and for high moisture Specification for Wood Construction. when placed in a hole drilled 1/32-inch conditions apply to design values for oversize. By reducing this load an addi- mechanical fasteners when the strength

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TABLE 29 CARRIAGE BOLTS: PLYWOOD AND METAL CONNECTIONS(a) Ultimate Lateral Load (lb)(b) Plywood Plywood Bolt Plywood End Edge Finger Tight 200-in.-lb Torque Diameter Thickness Distance Distance Without With Without With (in.) (in.) (in.) (in.) Washer Washer Washer Washer 1/2 1-1/2 3 1200 1480 1640 1830 3/8 5/8 1-1/2 3 (1430) (1710) (1860) (2230) 3/4 1-1/2 3 1710 2520 2160 2700 1/2 2 3 1280 — 1560 — 1/2 5/8 2 3 (1790) — (2320) — 3/4 2 3 1940 — 2710 — (a) Plywood was APA RATED SHEATHING Exposure 1 marked “PS 1” (all plies Group 1), face grain parallel to load. Side plate was 3/16"-thick steel. Bolts were No. 2 N.C. mild steel. (b) Values in parentheses are estimates based on other tests. Single shear with carriage bolt

TABLE 30 MACHINE BOLTS: PLYWOOD AND METAL CONNECTIONS(a) Ultimate Lateral Load (lb)(b) Plywood Plywood Bolt Plywood End Edge Single Shear Double Shear Diameter Thickness Distance Distance Finger 200 in.-lb Finger 200 in.-lb (in.) (in.) (in.) (in.) Tight Torque(c) Tight Torque(c) 1/2 1 3 1180 (1410) 970 (1160) 1/4 5/8 1 3 1200 (1430) 1130 (1350) 3/4 1 3 1500 (1810) 1380 (1650) 1/2 1-1/4 3 1490 (1790) 1430 (1710) 5/16 5/8 1-1/4 3 1370 (1640) 1260 (1510) 3/4 1-1/4 3 2040 (2450) 1770 (2130) 1/2 1-1/2 3 1730 2080 1510 1820 3/8 5/8 1-1/2 3 1680 (2010) 1650 (1980) 3/4 1-1/2 3 2120 2560 2330 2790 Double shear with machine bolt 1/2 2 3 1870 2240 — — 1/2 5/8 2 3 (2090) (2510) — — 3/4 2 3 2240 2960 — — (a) Plywood was APA RATED SHEATHING Exposure 1 marked “PS 1” (all plies Group 1), face grain parallel to load. Side plate was 3/16"-thick steel. Bolts were No. 2 N.C. mild steel, with washer. (b) Values in parentheses are estimates based on other tests. (c) Estimated values for 1/4" and 5/16" diameter bolts apply to torque level recommended by the bolt manufacturer.

NOTE: Tables 29 and 30 present ultimate lateral loads for single-shear and double- shear plywood-and-metal joints. The loaded plywood end distance was four times the diameter of the bolt. All speci- mens were tested with a 3/16-inch-thick steel side plate, and values should not be applied when steel is thinner.

Single shear with machine bolt

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ABOUT APA — THE ENGINEERED WOOD ASSOCIATION

APA – The Engineered Wood Association is a nonprofit trade association whose member mills produce approximately 70 percent of the structural wood panel products manufactured in North America. The Association’s trademark appears only on products manufactured by member mills and is the manufacturer’s assurance that the product conforms to the standard shown on the trademark. That standard may be an APA performance standard, the Voluntary Product Standard PS 1-95 for Construction and Industrial Plywood or Voluntary Product Standard PS 2-92, Performance Standards for Wood-Based Structural-Use Panels. Panel quality of all APA trademarked products is subject to verification through APA audit. APA’s services go far beyond quality testing and inspection. Research and promotion programs play important roles in developing and improving plywood and other panel construction systems, and in helping users and specifiers to better understand and apply panel products. Always insist on panels bearing the mark of quality – the APA trademark. Your APA panel purchase is not only your highest possible assurance of product quality, but an investment in the many trade services that APA provides on your behalf. For more information about APA functions and services, write APA – The Engineered Wood Association, P.O. Box 11700, Tacoma, Washington 98411-0700 or visit APA on the World Wide Web: http://www.apawood.org

OTHER PUBLICATIONS

The following industrial use publications are available from APA – The Engineered Wood Association: APA Product Guide: Grades and Specifications, Form J20. $2 Industrial Panel Selection Guide, Form T200. $5 Materials Handling Guide, Form M200. $3 APA Product Guide: Performance-Rated Panels, Form F405. $2 APA Product Guide: HDO/MDO Plywood, Form B360. $1 U.S. Product Standard PS 1-95 for Construction and Industrial Plywood, Form V995. $3

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TRANSPORT EQUIPMENT INDUSTRIAL USE 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, 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 DESK (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. G210B/Revised December 1997/0300

APA The Engineered Wood Association