What you need to know about -,APARATED SHEATHING treated plywood

?

HE NEW American Plywood Association (APA)

I Treating Grade trademarks serve a dual purpose. F'irst, they flag panels suitable for treating for the convenience of treaters. Second, and more important to the dealer, they help identify the proper panelfor the job.

The "Foundation Treating Grade" is primarily intended for the Permanent Wood Foundation. 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.

32116 15t32 lNcH

SIZED F()R SPACING EXTERIOR '---000..-.-

PS 1-83 C-G NER-108 FOUNDATION

[00K for trademarks like these to help you guide your customer In selectino the c0rrect pressure treated plywood panel for his proiect' Foundation Treating Grading is Jor PWF. Treating Grade should be used for fences, dedks and other construction within 6 in of ground. 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 wiit te permanently exposed to the weather. Siding, fencing, privacy screens, outbuildings and many other projecis tan successfully be constructed using APA itructural 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 l.

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; gaidening 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 level is for above ground

The rule of thumb to remember is: If 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 reiention 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 Foundation, the Foundation Treating Grade trademark is recommended. A .6 preservative retention level is needed here. lf 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.

Foim No. Q220, available from the American Plywood Association, P.O. Box 11700' Tacoma, Wa', 9841l, is an excellent source of information on preservative treated plywood. Form No. A400 has additional information on Permanent Wood F-oundations.