Building Design and Construction Handbook - Merritt - Ventech!

10.34 SECTION TEN
A structural panel may contain either softwoods or hardwoods. Panels approved
for use in building-code-regulated construction carry the trademark of a codeapproved
agency, such as APA—The Engineered Wood Association. Most construction
grades have either an Exterior or Exposure 1 durability classification and are
made with fully waterproof adhesives. Exposure classifications are defined as follows:
Exterior—panels that are suitable for permanent exposure to weather or moisture.
Exposure 1—panels that are suitable for uses not permanently exposed to the
weather but may be used where exposure durability to resist effects of moisture
due to construction delays, high humidity, water leakage, or other conditions of
similar severity is required.
Exposure 2—panels that are suitable for interior use where exposure durability
to resist effects of high humidity and water leakage is required.
Interior—panels that are suitable for interior use where they will be subjected
to only temporary, minor amounts of moisture.
10.12.1 Standards for Structural Panels
Structural panels approved for building-code-regulated construction are manufactured
under one or more of three standards:
1. U.S. Product Standard PS 1-95 for Construction & Industrial Plywood (PS
1). It applies to plywood only. This voluntary product standard covers the wood
species, veneer grading, glue bonds, panel construction and workmanship, dimensions
and tolerances, marking, moisture content, and packing of plywood intended
for construction and industrial uses. Also included are test methods to determine
compliance and a glossary of trade terms and definitions. A quality certification
program is provided, whereby qualified testing agencies inspect, sample, and test
products identified as complying with the standard. Information regarding generally
available sizes, methods of ordering, and reinspecting practices also is provided.
2. Voluntary Product Standard PS 2-92, Performance Standard for Wood-Based
Structural-Use Panels (PS 2). It applies to all types of wood-based panels (typically
plywood, OSB, and composite). It establishes requirements for assessing the acceptability
of wood-based structural-use panels for construction sheathing and single-floor
applications. It also provides a basis for common understanding among
the producers, distributors, and users of these products. It covers performance requirements,
adhesive bond durability, panel construction and workmanship, dimensions
and tolerances, marking, and moisture content of structural-use panels. The
standard also includes test methods to determine compliance and a glossary of trade
terms and definitions. A quality certification program is provided, whereby qualified
testing agencies inspect, sample, and test products for qualification under the standard.
3. APA Performance Standards and Policies for Structural-Use Panels (PRP
108). It is similar to PS 2 but also includes performance-based qualification procedures
for siding panels.
10.12.2 Plywood Grades
Plywood grades are generally identified in terms of the veneer grade used on the
face and back of the panel; for example, A-B, B-C, . . . , or by a name suggesting