Installation Guide

Floor Construction
ENGINEERED WOOD CONSTRUCTION GUIDE
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FORM NO. E30V
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© 2011 APA – THE ENGINEERED WOOD ASSOCIATION
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WWW.APAWOOD.ORG
38
APA RATED SHEATHING Exposure 1 may be used where temporary exposure to moisture or weather is expected dur-
ing construction. However, only Exterior panels should be used where long-term exposure to moisture or weather will
be required.
In some nonresidential buildings, greater traffic and heavier concentrated loads may require construction in excess of
the mini mums given. Where joists are 16 inches on center, for example, panels with a Span Rating of 40/20 or 48/24
will give additional stiffness and strength. For beams or joists 24 or 32 inches on center, 1-1/8 Performance Category
panels (APA RATED STURD-I-FLOOR 48 oc) will provide additional stiffness and strength.
Lightweight Concrete Over APA Panels
APA RATED SHEATHING or STURD-I-FLOOR panels are an excellent base for light weight concrete floors. See “APA
Rated Sturd-I-Floor,” page 31, or “APA Panel Subflooring,” page 37, for application recom mendations. For gypsum con-
crete recom mendations, contact manufacturer of floor topping. Install panels con tinuous over two or more spans
with the strength axis across supports. Use a moisture barrier when recom mended by con crete manufacturer. (See
“Noise Transmission Control,” page 77, and Figure 38 for an illustration of a typical assembly.)
APA Plywood Underlayment
Underlayment is a special grade of plywood that has enhanced resistance to face-veneer punctures. This is accom-
plished by imposing special limitations on the face veneer thickness, species of the face veneer and voids beneath the
face veneer. Other grades, such as A-C Exterior, are only suitable if they have the additional Underlayment designation
or “Plugged Crossbands Under Face” noted in the trademark. Plywood meeting the Underlayment standard in PS 1, will
have the word, “Underlayment” in the trademark (see example on page 10). Plywood STURD-I-FLOOR, however, also
meets the enhanced puncture-resistance requirements for Underlayment, in addition to being Span Rated. (See “APA
Rated Sturd-I-Floor,” page 31.) Refer to APA Data File: Installation and Preparation of Plywood Underlayment for Resilient Floor
Covering, Form L335, for installation recommendations.
Stagger end joints (optional)
APA RATED SHEATHING
2x rim joist or
APA Rim Board
Wood strip, wood
blocks, or lightweight
concrete flooring
1/8" spacing is
recommended at all edge
and end joints unless otherwise
indicated by panel manufacturer
2x joist, I-joists
or floor trusses
FIGURE 5
APA PANEL SUBFLOORING
Strength axis
Notes:
1. Provide adequate moisture
control and use ground cover
vapor retarder in crawl space.
Subfloor must be dry before
applying subsequent floor.
2. For buildings with wood or
steel framed walls, provide 3/4"
temporary expansion joints with
separate floor framing embers
and discontinuous wall plates
over the joints, at intervals that
limit continuous floor areas to
80 feet maximum in length or
width, to allow for accumulated
expansion during construction
in wet weather conditions. Refer
to APA Technical Note:
Temporary Expansion Joints for
Large Buildings, Form U425 for
detailed information.
2x treated sill
Panel edges T&G or
supported on blocking
(shown) unless covered
with underlayment,
light-weight concrete or
wood strip flooring
perpendicular
to panel
edges.