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
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Product Standard PS 1 or PS 2. Plywood APA STURD-I-FLOOR meets PS 1 Underlayment specifications, but in addition to
qualifying as underlayment, STURD-I-FLOOR carries a Span Rating (thin underlayment carries no Span Rating). STURD-
I-FLOOR is easy to use and specify because the maximum recommended spacing of floor joists – or Span Rating – is stamped
on each panel. Panels are manufactured with Span Ratings of 16, 20, 24, 32 and 48 inches. These assume use of the panel
continuous over two or more spans with the long panel dimension or strength axis across supports.*
Glue-nailing is recommended for STURD-I-FLOOR panels, though panels may be nailed only. Recommendations for both
methods are given in Table 11. (See “The APA Glued Floor System,” page 35, for more detailed gluing recom mendations.)
Always protect smooth panel faces and tongue-and-groove edges from damage prior to and during application. Install with
smooth side up. Recom mended live loads are given in Table 12.
If long-term exposure to the weather is required, specify Exterior panels.
Although STURD-I-FLOOR is suitable for direct application of carpet and pad, an additional thin layer of underlayment is rec-
ommended under tile, sheet flooring or fully adhered carpet. This added layer restores a smooth surface over panels that may
have been scuffed or roughened during construction, or that may not have received a suffi ciently sanded surface. When plywood
STURD-I-FLOOR with “sanded face” is specified, the surface is also suitable for direct application of resilient floor covering. If
a “sanded face” panel is to be used, however, care must be taken during construction to prevent damage or roughening of the
sanded face. Tongue-and-groove edges are recommended to be glued under thin floor coverings to assure snug joints.
TABLE 11
APA RATED STURD-I-FLOOR
(a)
Span Rating
(Maximum
Joist
Spacing)
(in.)
Panel
Performance
Category
(d)
Fastening: Glue-Nailed
(b)
Fastening: Nailed-Only
Nail Size
and Type
(e)
Maximum Spacing (in.)
(c)
Nail Size
and Type
(e)
Maximum Spacing (in.)
(c)
Supported
Panel Edges
(f)
Intermediate
Supports
Supported
Panel Edges
(f)
Intermediate
Supports
16 19/32, 5/8
6d ring- or
screw-shank
(g)
6
(h)
12
6d ring- or
screw-shank
6 12
20
(i)
19/32, 5/8
6d ring- or
screw-shank
(g)
6
(h)
12
6d ring- or
screw-shank
6 12
24
23/32, 3/4
6d ring- or
screw-shank
(g)
6
(h)
12
6d ring- or
screw-shank
6 12
7/8
8d ring- or
screw-shank
(g)
6 12
8d ring- or
screw-shank
6 12
32 7/8
8d ring- or
screw-shank
(g)
6 12
8d ring- or
screw-shank
6 12
48 1-3/32, 1-1/8
8d ring- or
screw-shank
(j)
6 (k)
8d ring- or
screw-shank
(j)
6 (j)
(a) Special conditions may impose heavy traffic and concentrated
loads that require construction in excess of the minimums shown.
See page 43 for heavy-duty floor recommendations.
(b) Use only adhesives conforming to APA Specification AFG-01 or
ASTM D3498, applied in accordance with the adhesive manufac-
turer’s recommendations. If OSB panels with sealed surfaces and
edges are to be used, use only solvent-based glues; check with
panel manufacturer.
(c) Increased fastening schedules may be required where floor is
engineered as a diaphragm.
(d) Panels in a given Performance Category may be manufactured
in more than one Span Rating. Panels with a Span Rating greater
than the actual joist spacing may be substituted for panels of the
same Performance Category with a Span Rating matching the
actual joist spacing. For example, Performance Category 19/32
Sturd-I-Floor 20 oc may be substituted for Performance Category
19/32 Sturd-I-Floor 16 oc over joists at 16 inches on center.
(e) See Table 5, page 14, for nail dimensions.
(f) Supported panel joints shall occur approximately along the center-
line of framing with a minimum bearing of 1/2 inch. Fasten panels
3/8 inch from panel edges.
(g) 8d common nails may be substituted if ring- or screw-shank nails
are not available.
(h) Check with local building official; some local jurisdictions permit
nail spacing at 12 inches oc.
(i) Maximum joist spacing for 20 oc Span Rating is 19.2 inches.
(j) 10d common nails may be substituted with Performance Category
1-1/8 panels if supports are well seasoned.
(k) Space nails maximum 6 inches for 48-inch spans and 12 inches
for 32-inch spans.
*Note: The Span Rating in the trademark applies when the long panel dimension or strength axis is across supports unless the strength axis is
otherwise identified.