| SELECTING AND SPECIFYING APA PANELS Manufacturing and Performance Standards
Panels for construction and industrial applications can be
manufactured in a variety of ways - as plywood (cross-laminated wood veneer), as composite
panels (veneer faces bonded to wood strand cores), or as oriented strand board (OSB).
Some plywood panels are manufactured under the detailed
manufacturing specifications or under the performance testing provisions of Voluntary
Product Standard PS 1-95 for Construction and Industrial Plywood,developed cooperatively
by the plywood industry and the U.S. Department of Commerce. Other plywood panels,
however,as well as composite and OSB panels, are manufactured under the provisions of APA
PRP-108, Performance Standards and Policies for Structural-Use Panels, or under Voluntary
Product standard PS 2-92, Performance Standard for Wood-Based Structural-Use Panels, that
establish performance criteria for specific designated construction applications.
These APA Performance Rated Panels are easy to use and
specify because the recommended end use and maximum support spacing are clearly indicated
in the APA trademark. By broadening the range of panel configuration and composition, APA
Performance Rated Panels allow more efficient use of raw materials. APA PRP-108
Performance Standards are recognized by the National Evaluation Service and HUD. (a)
PRP-108, PS-1 and/or the PS-2 grade conformance where applicable are given in the lower
portion of the APA trademark. Plywood panels, depending on glueline classification, veneer
species and thickness, etc., are in many instance identical to panel grades as defined in
Product standard PS 1-95.
Typical APA Performance Rated Panel trademarks are
illustrated and explained on page 6.
Grade Designations
Structural panel grades are generally identified in terms
of the veneer grade used on the face and back of the panel (e.g., A-B, B-C, etc.). or by a
name suggesting the panel's intended end use (e.g., APA RATED SHEATHING, APA RATED
STURD-I-FLOOR, etc.). See Tables 2-4.
Veneer grades define veneer appearance in terms of natural
unrepaired growth characteristics and allowable numbe5r and size of requires that may be
made during manufacture. See Table1 below.
The highest quality commonly available veneer grade is A.
The minimum grade of veneer permitted in Exterior plywood is C-grade. D-grade veneer is
used in planes intended for interior use or applications protected from permanent exposure
to weather.
Sanded, Unsanded and Touch-Sanded
Panels
Panels with B-grade or better veneer faces are always
sanded smooth in manufacture to fulfill the requirements of their intended end use -
application such as cabinets, shelving, furniture, built-ins, etc. APA RATED SHEATHING
panels are unsanded since a smooth surface is not a requirement of their intended end use.
Still other panels- APA UNDERLAYMENT, APA RATED STURD-I-FLOOR, APA C-D PLUGGED, and APA
C-C PLUGGED - required only touch sanding for "sizing" to make the panel
thickness more uniform.
| TABLE 1 VENEER
GRADES
|
A |
Smooth, paintable. Not more than 18 neatly
made repair's boat, sled, or route type, and parallel to grain, permitted. Wood or
synthetic repairs permitted. May be used for natural finish in less demanding
applications. |
|
B |
Solid surface. Shims, sled or router repairs,
and tight knots to 1 inch across grain permitted. Wood or synthetic repairs permitted.
Some minor splits permitted. |
|
C
Plugged |
Improved C veneer with splits limited to
1/8-inch width and knot-holes or other open defect limited to 1/4 x 1/2 inch. Wood or
synthetic repairs permitted. Admits some broken grain. |
|
C |
Tight knots to 1-1/2 inch. Knotholes to 1 inch
across grain and some to 1-1/2 if total width of knots and knotholes is within specified
limits. Synthetic or wood repairs. Discoloration and sanding defects that do not impair
strength permitted. Limited splits allowed. Stitching permitted. |
|
D |
Knots and knotholes to 2-1/2-inch width across
grain and 1/2 inch larger within specified limits. Limited splits are permitted. Stitching
permitted. Limited to Exposure 1 or Interior panels. |
|
|
Unsanded and touch-sanded panels, and panels with B-grade
or better veneer on one side only, usually carry the APA trademark on the panel back.
Panels with both sides of B-grade or better veneer, or with special overlaid surfaces
(such as HIGH DENSITY OVERLAY) usually carry the APA trademark on the panel edge.
(a) The National Evaluation Service is sponsored jointly by
the three model code organizations - the Building Officials and Code Administrators
International, promulgators of the National Building Code; the International Conference
of Building Officials, promulgators of the Uniform Building Code; and the Southern
Building Code Congress International, promulgators of the Standard Building Code. See
National Evaluation Service Report No. NER-108 for allowable values and/or conditions of
use concerning material presented in this brochure. It is subject to reexamination,
revisions, and possible cancellation.
HUD recognition of wood-based APA Performance Rated Panels
is contained in Use of Materials Bulletin UM-40c, or in UM-64 for APA Rated Siding-303
(plywood). |
