Answers to common questions about I engineered wood panels

By Merritt Kline APA Product Support Specialist

Ir.lHANCES ARE, if you're involved with engineered \-rwood. vou've had an occasion to call the manufacturer about some aspect of installation or design. As more designers specify, more builders use and more dealers stock engineered wood products, more questions arise, from proper installation details to selecting the right product for the right application.

At the APA Product Support Help Center in Tacoma, Wa., specialists handle hundreds of inquiries a week from dealers, builders, framers and designers who are using or planning to use engineered wood products. Here are some of the most frequently-asked questions:

Q wni"r, is stronger, plywood or oSB?

A A The two products are virtually interchangeable. That's because both products, although different in composition and appearance, are manufactured according to the same performance standards. These standards apply the same performance criteria to both products for their designated end uses-sheathing, single-layer flooring, and exterior siding. The performance standards under which plywood and OSB are qualified were developed to ensure reliable performance in service, to address a changing wood fiber supply, and to remove obstacles to innovative manufacturins technology.

Q tf rrr" gradestamp reads "Sized For Spacing" must the panels still be spaced 1/8" at panel edges?

Yes. Since wood is a biolosical material and can expand when it absorbs moisture, panels should be spaced at ends and edges. The "Sized For Spacing" notification is intended to facilitate proper installation and specifies that the panels may be cut less than nominal dimensions from the mill to account for any expansion that may occur. The size tolerance of a 4'x8' "Sized For Spacing" panel, therefore, may be 1/8" less than the specified length and width, e.g.,47-718"x95-718". However, since the size tolerance given in the performance standard allows up to 1/8" less than the specified length and width, a 47J/8"x 95-7/8" panel may or may not be stamped "Sized For Spacing."

How do I know if a particular panel meets the live and dead load requirements?

A A

The fastest way to determine live and dead load capacities is to check the APA load span tables for roof and floor applications in the APA Residential and Commercial Design Guide. The tables provide allowable live loads for panels installed over common support (oist, truss or rafter) spacing configurations. The guide is available from our publications department or online at www.apawood.org.

Q no., structural panel siding have shear values? be sanded smooth. Wall and vertical surfaces allow water to "shed" quickly. Later, after the roof framing, sheathing and roofing are installed, roof overhangs (if provided) will further protect the sheathing from exposure, although the panels may get wet from exposure to rain especially on the lower parts of walls or if wind-driven rain occurs.

Plywood (all-veneer) APA Rated Siding is often used for shear wall sheathing. The thickness of the panel at the point of nailing on the panel edges governs shear values. Other APA Rated Siding panel types may also qualify for shear values on a proprietary basis. To check for specific shear values, refer to the APA Residential and Commercial Design Guide.

Q Wrr"t is the difference between Exposure 1 and Exterior panels?

A n pe trademarked panels may be produced in four exposure durability classifications: Exterior, Exposure 1, Exposure 2, and Interior. The epposure durability classification relates to glue bond, and thus to structural integrity.

Exterior panels have a fully waterproof bond and are designed for applications subject to exposure to the weather or to moisture for its entire service life. Exposure 1 panels have a fully waterproof bond and are designed for applications where construction delays may be expected prior to providing protection.

Exposure 1 panels are made with the same exterior 'adhesives used in Exterior panels. However, because other compositional factors may affect bond performance, only Exterior panels should be used for permanent exposure to the weather.

Exposure I panels may also be used when exposure to the outdoors is on the underside only, such as roof overhangs.

How long can structural wood panels be exposed to the weather?

Before installing the exterior and interior finish, wall sheathing should be allowed to dry so that moisture absorbed during construction will not be trapped within the wall cavity. For roofs, APA recommends covering the sheathing as soon as possible after installation. This will allow the interior of the building to start the drying process. If this is not possible, and the roof sheathing has been exposed for a period oftime, allow the roof sheathing to dry (from the underside) before closing in the roof cavity or attic.

Q Ar. the specification and use recommendations developed by APA applicable to products certified by other agencies?

ASince the APA trademark appears only on products manufactured by member mills of APA, it signifies that the products are subject to the association's audit-arguably the toughest and most comprehensive quality auditing program in the industry. The technical information and product use recommendations developed by APA are based on research and testing of APA trademarked products only and therefore does not apply to panels certified by other agencies.

Q Wft"t should be ustd when the architect specifies underlayment?

A Several iranel grades and lay-ups are suitable for use as underlayment, however, the appropriate choice depends upon the type of finish flooring. For example, only fullysanded, veneer-faced underlayment panels meet APA recommendations for applications under resilient floor coverings such as tile or sheet flooring or fully-adhered carpet.

A

A There are many factors that affect the durability of wood structural panels, and each situation is unique. Although subjective, one way to determine if floor panels are suitable for use after a period of exposure is to walk on them. If they feel solid compared to your previous experiences with similar panels, spans and supports, they are "OK." After bxposure to weather, panels often look rough but remain structurally serviceable. After the building is l'closed in" and protected from the weather, the floor should be allowed to dry to in-service moisture conditions.

Before installing any finish flooring, the floor deck should be inspected for flatness betweenjoists, and also for smoothness along end and edge joints between panels. Any ridges or thickness swelling at these locations should

One way to determine if floor panels are suitable for use after a period of exposure is to walk on them.

Other underlayment grades meet APA recommendations for less demanding floor covering applications such as carpet and pad and ceramic tile. To be assured that the right underlayment is used, check the APA Underlayment Guide at www.apawood.org.

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Adams Building Materials, Winter Haven, Fl., has opened a lumberyard and truss plant in Sanford, Fl. (Paul Hertko, truss plant gen. mgr.), and a truss plant in Brooksville, Fl. (Jim Countryman, gen. mgr.)

Forbes Lumber Co., Bald Knob, Ar., has closed after 53 years due to the owner's retirement...

84 Lumber is remodeling yards in Plainview, Tx.; London and Maysville, Ky., into the 84+ format...

Ashdown Building Materials, Ashdown, Ar., has been acquired by OMS Lumber Co., Ashdown, Odis Blackman, owner

Beeson hrmber & Hardware is relocating to a larger, l6-acre site in High Point, N.C.

Walker Bros. Ltd., Baileyton, Al., has conrpleted remodelirig its store and adding office space

Hardman Lumber Co., Arkadelphia, Ar., is installing a guard shack to check outgoing orders ...

Hometown Building Supply & Hardware, Ardmore, Al., has expanded its paint dept., adding a S-gallon shaker...

Home Depot opens new stores this month in Killeen, Tx., and Hendersonville, N.C.; plans to open its first prototype stand-alone flooring showroom late this year in the Dallas area; is negotiating for a 18.65-acre site in Baytown, Tx., and agreed to buy threesam's Club sites in Argentina, with plans to have eight locations in the country by the end of next year ...

I-oweb Cos. recently opened a I 50,000-sq. ft. supdrsiore in Kingwood, Tx., and replacement stores in Sumter and Orangeburg, S.C. (James Padgett, store mgr.l the chain plans a fall opening in Shallotte, S.C., and a December opening in Pascagoula, Ms.; agreed to build in Winter Haven, Fl., and is considering a site in Pensacola, Fl. lUuor:sn:ns/trrurlcunrrs

Loweb is relocating its Intemet Business Group to Huntersville, N.C., but keeping the group's customer service unit in Wilkesboro, N.C.

Anniversaries: Hardman Lumber Co., Arkadelphia, Ar., 60th ...Tbxas Wholesale Building Materials, Carrollton, Tx., lOth ...

New Web site: Swift Supply, Atrnore, Al., www.swiftsupply. com ... Smith-Phillips Lumber & B ui lding S upply, Winston-Salem, N.C., www.smithphillipslumber. com Wheeler's Building Materials, Rome, Ga., www. wheelers.com...

Columbus Lumber Co., Brookhaven, Ms., has acquired Phillips Brathers Lumbei Co., Brookhaven; Paul Phillips is now operations mgr. of the new CLC South plant

Hudson Lumber & Truss. Purvis, Ms., relocated its sawmill sales office to Moody, Al.; Jay Johnston, Wil Johnston and Steve Mathey are new staffers

Gulf States Paper Corp. has dropped the Loper Lumber Co. name for its Moundville, Al., wood products operation, renaming the sawmill Gulf States

Do it Best Corp. has shipped the first version of Do it Best Info Deluxe software, integrating the co-op's CD-Rom catalog and its mainframe billing and inventory systems, helping members to maintain billing, pricing and inventory records as well as create customized catalogs online ...

(J.5. Concrete, Houston, Tx., has completed its acquisition of Butler Ready Mix Concrete, Dallas, Tx.

Weyerhaeuser broke off negotiations to sell its Marshfield, Wi., door manufacturing business to Saunders Karp & Megrue (see March, p. 29)

American Wire Products, Frankfort, Ky., opened a warehouse in Temple City, Ca.

Hancock Timber Resource Group completed the purchase of Alliance Forest Products' 367,000 acres of timberlands plus 35,000 acres ofleased land ...

Lovetl Farms Inc., Miami, Fl., has been acquired by nursery operator Hines Horticulture Inc., Irvine, Ca.

U.S. Plastic Lumber, Boca Raton, Fl., bought the assets of plastic shipping platform producer Baton Enterprises

Atlas Roofing Corp., Meridian, Ms., acquired Qwens Corning's Falcon Foam business

B uildNer, Research Triangle Park, N.C., agreed to acquire NxTrend Te c hno lo g ies, Colorado Springs, Co., and has filed for a proposed initial public offering

Construction Supply Exchange, Orlando, Fl., and ChanneLinx, Greenville, S.C., this month are launching csXnet.com, a digital marketplace for the building materials industry

EqualFooting.com, Dulles, Va., is a new business-to-business online marketplace for the small construction and manufacturing industries

American Forest & Paper Association signed a Memorandum of Understanding between its Sustainable Forestry Initiativ e and the Forest Prcducts Laboratory ...

Trex Co., Winchester, Va., was named Vendor of the Year by OrePac BuiWing Products ...

Housing starts in Feb. (latest figs.) rose I .37o to a seasonally adjusted annual rate of 1.78 million single family starts slipped nearly 4Vo to l.3l million, multifamily jumped l9.5%o to a rate of 472,040 units ... permits fell87o to a 1.63 million rate ... in the South, starts decreased ll.3Vo, while permits slipped 3.8%.