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Building Design and Construction Handbook - Merritt - Ventech!

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TABLE 10.17 Veneer-Grade <strong>Design</strong>ations<br />

Grade Description<br />

N<br />

A<br />

B<br />

C<br />

Plugged<br />

WOOD CONSTRUCTION 10.35<br />

the panel’s intended end use, such as APA Rated Sheathing or APA Rated Sturd-<br />

I-Floor.<br />

Veneer grades define veneer appearance in terms of natural, unrepaired-growth<br />

characteristics <strong>and</strong> allowable number <strong>and</strong> size of repairs that may be made during<br />

manufacture (Table 10.17). The highest quality veneer grades are N <strong>and</strong> A. The<br />

minimum grade of veneer permitted in Exterior plywood is C grade. D-grade veneer<br />

is used in panels intended for interior use or applications protected from permanent<br />

exposure to weather.<br />

Panels with B-grade or better veneer faces are always s<strong>and</strong>ed smooth in the<br />

manufacturing process to fulfill the requirements of their intended end use—<br />

applications such as cabinets, shelving, furniture, <strong>and</strong> built-ins. Rated Sheathing<br />

panels are uns<strong>and</strong>ed since a smooth surface is not a requirement of their intended<br />

end use. Still other panels, such as Underlayment, Rated Sturd-I-Floor, C-D<br />

Plugged, <strong>and</strong> C-C Plugged, require only touch s<strong>and</strong>ing for ‘‘sizing’’ to make the<br />

panel thickness more uniform.<br />

Uns<strong>and</strong>ed <strong>and</strong> touch-s<strong>and</strong>ed panels, <strong>and</strong> panels with B-grade or better veneer<br />

on one side only, usually carry the trademark on the panel back. Panels with both<br />

sides of B-grade or better veneer, or with special overlaid surfaces, such as High-<br />

Density Overlay, usually carry the trademark on the panel edge.<br />

10.12.3 Plywood Group Number<br />

Plywood can be manufactured from over 70 species of wood. These species are<br />

divided on the basis of strength <strong>and</strong> stiffness into five groups under U.S. Product<br />

St<strong>and</strong>ard PS 1-95. Strongest species are in Group 1; the next strongest in Group 2,<br />

etc. The group number that appears in the trademark on some APA trademarked<br />

Smooth surface ‘‘natural finish’’ veneer. Select, all heartwood or all sapwood.<br />

Free of open defects. Allows not more than six repairs, wood only, per 4- � 8-ft<br />

panel, made parallel to grain <strong>and</strong> well matched for grain <strong>and</strong> color.<br />

Smooth, paintable. Not more than 18 neatly made repairs, boat, sled, or router<br />

type, <strong>and</strong> parallel to grain, permitted. May be used for natural finish in lessdem<strong>and</strong>ing<br />

applications. Synthetic repairs permitted.<br />

Solid surface. Shims, circular repair plugs, <strong>and</strong> tight knots up to 1 in across grain<br />

permitted. Some minor splits <strong>and</strong> synthetic repairs permitted.<br />

Improved C veneer with splits limited to 1 ⁄8-in width <strong>and</strong> knotholes <strong>and</strong> borer<br />

holes limited to 1 ⁄4 � 1 ⁄2 in. Admits some broken grain. Synthetic repairs<br />

permitted.<br />

C Tight knots to 11 ⁄2 in. Knotholes up to 1 in across grain <strong>and</strong> some up to 11 ⁄2 in if<br />

total width of knots <strong>and</strong> knotholes is within specified limits. Synthetic or wood<br />

repairs <strong>and</strong> discoloration <strong>and</strong> s<strong>and</strong>ing defects that do not impair strength<br />

permitted. Limited splits allowed. Stitching permitted.<br />

D Knots <strong>and</strong> knotholes up to 21 ⁄2-in wide across grain <strong>and</strong> 1 ⁄2 in larger within<br />

specified limits, limited splits, <strong>and</strong> stitching permitted. Limited to Exposure 1 or<br />

interior panels.

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