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APA Rating - Sheet Goods Cheat Sheet by

sheet     goods     apa

Introd­uction: APA

While there are many more products than are included here, once you know how to read and understand these sheathing and sheet goods grade stamps, you’ll be able to apply it to other sheet goods.

Shown here is a common grade stamp and here’s what it means:

APA – This is the official logo for APA – The Engineered Wood Associ­ation. It signifies that the manufa­cturer is a member of APA, and the panel has been manufa­ctured and tested in accordance with APA standards.


A combined subflo­or-­und­erl­ayment, single­-layer flooring intended for use under carpet and pad, the panels are available as plywood or OSB, with either tongue and groove or square­-edge treatment.


Sturd-­I-Floor panels come in various span ratings: 16, 19.2, 24, 32 and 48 inches. On this panel, 24 OC sized for spacing indicates this is designed for use over structural framing supports spaced a maximum of 24 inches on center (OC).

All floor and roof sheathing is designed to be applied with its long dimension perpen­dicular to (across) structural supports. The span ratings are based on the sheet being applied with its “strength axis” (long dimension) spanning at least three supports. While these span recomm­end­ations are widely accepted, actual maximum spans are establ­ished by local building codes.

T&G NET WIDTH 47-1/2

A square edged panel covers 48-inches, but when tongue and grove (T&G) panels are interl­ocked, the joint reduces the installed surface area by ½ inch.


This is a reference to the type of adhesives used to bond the panel and how well it will stand up to moisture. A panel with a rating of Exposure 1 is designed to withstand the effects of moisture resulting from constr­uction delays and can be left exposed in applic­ations such as soffit material under a roof eave where it is visible, but protected from the elements.

Exposure 1 panels are not suitable for use in applic­ations where they would be fully exposed to weather, as extended exposure to moisture will cause the adhesives to break down, resulting in delami­nation.

APA Sheating


This is the thickness label. It gives the panel thickness in thousa­ndths of an inch.

Because of varying regula­tions by the agencies with authority over the manufa­cture of wood-based panels – the U.S. Department of Commerce and the National Institute of Standards and Technology (NIST) – two statements of thickness are required in order to meet legal requir­ements.

000 – Mill identi­fic­ation number

Every APA member mill is issued a three digit ID number. If you have a problem with a batch of panels (rare, but it happens), this number can be used to trace the panels back to the mill where they were produced.

PS 1-09

Refers to Voluntary Product Standard PS 1-09 – Structural Plywood. Adopted by APA on May 1, 2010, the standard was developed under Commerce Department proced­ures.

The intent was to provide a common unders­tanding among manufa­ctu­rers, distri­butors and users of structural wood panels. It provides defini­tions for the types and grades of structural panels and lays out specific requir­ements for acceptable wood species and adhesives, veneer grading, panel constr­uction, dimension tolerances and moisture content.


This panel is intended as a “single floor” applic­ation. One sheet of Sturd-­I-Floor provides both the structural floor deck, as well as the underl­ayment for the floor finish.

PRP-108 –APA PRP-108

Quality Assurance Policies for Struct­ura­l-Use Panels – requires the mill to submit to an on-site inspection program. APA issues daily test reports and weekly audits to verify the mill’s products are in compliance with the quality standard. In addition, the mill must agree to employ an APA Quality Management System and certify mill staff through APA’s Certified Quality Technician program.


This is the perfor­mance category. It gives the panel thickness in fractions of an inch. As discussed above, because two statements of thickness are required, this is the dimension that you’ll find listed in the Intern­ational Building Code (IBC), Intern­ational Reside­ntial Building Code (IRC), on plan drawings and in constr­uction specif­ica­tions.

You may be asking yourself: It’s a sheet of floor deck – why can’t they just call it ¾ inch? When you order single applic­ation floor deck for a 24-inch OC floor system, your order should look something like this: 23/32-­inch, OSB, 24 OC, Sturd-­I-F­loor, 100-sh­eets.

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