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THE NEW American Plywood Association (APA)

ITreating Grade trademarks serve a dual purpose. First, they flag panels suitable for treating for the convenience of treaters. Second, and more important to the dealer, they help identify the proper panel for thejob.

The "Foundation Treating Grade" is primarily intended for the Permanent Wood F'oundation. Foundation Treating Grade panels are graded C-C or better, with full exterior durability classification. The grade stamp of the American Wood Preservers Bureau or a similar agency should also be present on the treated panel. This stamp includes information on preservative retention levels. Panels must be treated to a .6 retention level for PWF applications.

Story at a Glance

How the new APA Treating Grade trademarks on plywood identify which panel to use. . examples of which retention level does what. what PWF requires.

APA has another treating grade, which is used on panels C-D grade or better, with an Exposure I durability classification. These panels are identified as "Treating Grade." Treating Grade panels should have a retention level of .4 or better for use in a myriad of applications where the panel will be less than six inches from the ground or will be in ground contact. Common uses for Treating Grade panels include swimming pools; decks, especially under indoor-outdoor carpeting; skirting around foundations on houses and mobile homes; gardening trays and planters; bulkheads; and fencing or privacy screens which will be in contact with the ground. Other Treating Grade panels may show treating agency stamps identifying the product as having a retention level of .25. This retention levelis for above eround

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Sized For Spacing Exterior 000

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use, where moist conditions may promote decay or insect infestation. Examples include swimming pool covers and sheathing in tropical climates.

Of course, exterior grade, untreated panels are quite appropriate for most outdoor panel applications which will be permanently exposed to the weather. Siding, fencing, privacy screens, outbuildings and many other projects can successfully be constructed using APA structural panels bearing the full exterior durability classification. Panels which may be exposed for a time, but eventually covered, such as roof and wall sheathing and subflooring, can be designated Exposure 1,

The rule of thumb to remember is: lf the panels will be less than six inches from ground contact or in contact with the ground, Treating Grade should be used, along with an AWPB or similar testing agency mark designating a .4 preservative retention level. Panels with .25 retention level designation and the Treating Grade trademark may be used for very moist, above ground applications. If the panels will be used for the Permanent Wood F'oundation, the F'oundation Treating Grade trademark is recommended. A .6 preservative retention level is needed here. If the panels will be exposed permanently to weather but will not be in ground contact, exterior grade panels, with no Treating Grade designation, are usually appropriate.

Form No. Q220, available from the American Plywood Association, P.O. Box 11700, Tacoma, Wa., 9841 I, is an excellent source of information on preservative treated plywood. Form No. ,4400 has additional information on Permanent Wood F-oundations.