| Sand subfloor joints if necessary to smooth
surface prior to installing underlayment or finish flooring. 2. Combined subfloor-underlayment (under carpet and pad)(13)
- Combined subfloor-underlayment panels shall be (specify appropriate grade):
APA RATED STURD-I-FLOOR EXP1, or
APA RATED STURD-I-FLOOR EXP.
Install with the long dimension or strength axis of
the panel across supports, and with panel continuous over two or more spans.
Panels edges shall be tongue-and-groove or supported on 2-inch lumber blocking installed
between joists. Protect against damage until finish floor is installed.
Stagger panel end joists. Panel end joints
shall occur over framing. Spacing of 1/8" is recommended at all panel ends
and edges, unless otherwise indicated by the panel manufacturer.(9)
For nailed floor, nail panels 6" o.c. at supported
panel edges and 12" o.c. at intermediate supports, except that when supports are
spaced 48" o.c. space nails 6" o.c. at all supports. Use 6d ring- or
screw-shank nails for panels 3/4" thick or less, and 8d for thicker panels. With
1-1/8" panels, 10d common nails may be used if supports are well seasoned.(10)(11)(12)
Fill and thoroughly sand edge joints.(14)
Lightly sand any surface roughness, particularly around fasteners.
For field-glued floors, use adhesives meeting APA
Specification AFG-10 or ASTM D3498, applied in accordance with the manufacturer's
recommendations. If OSB panels with sealed surfaces and edges are used, use only solvent
based, glues; check with panel manufacturer. Apply continuous line of glue (1/4"
thick) on joists, and continuous or spaced line of glue (1/8" thick) in groove of
tongue-and-groove panels. Use 6d ring- or screw-shank nails spaced 12" o.c. at panel
ends and intermediate bearings.(10)(15)
3. Underlayment (over subflooring) -
Plywood underlayment shall be (specify appropriate grade(16):
APA UNDERLAYMENT INT
APA UNDERLAYMENT EXT
APA UNDERLAYMENT C-C PLUGGED EXT, or
APA C-C PLUGGED EXT.
When 19/32" or thicker, APA RATED STURD-I-FLOOR EXP 1
or 2 or APA RATED STURD-I-FLOOR EXT may be specified. Apply underlayment just prior
to laying finish floor and protect against damage unit finish floor is installed.
For maximum stiffness, install underlayment with the face
grain across supports. Stagger panel end joints (optional under carpet and pad) with
respect to each other and offset all joints by at least tow inches from joints in the
subfloor panels.Butt panel ends and edges to close but not tight fit (1/32"
space is recommended).Nail 6" o.c. along panel edges and 8" o.c. each
way throughout remainder of panel with 3d ring-shank nails for panel thicknesses of
11/32" or 1/2", or 4d spaced 6" o.c. along edges and 12"o.c.
each way for thicker panels up to 3/4" (11)(17)
Fastener length should be approximately equal to the total
thickness of the underlayment and subfloor.
Fill and thoroughly sand edge joints(14) Lightly
and any surface roughness, particularly around fasteners.
D. Wall Sheathing
1. Panel wall sheathing shall be (specify
appropriate grade):
APA RATED SHEATHING EXP1
APA RATED SHEATHING EXT
APA RATED STRUCTURAL I RATED SHEATHING EXP 1
APA STRUCTURAL I RATED SHEATHING EXP, or
APA RATED WALL BRACING EXP1.
Spacing of 1/8" is recommended at panel ends
and edges, unless otherwise indicated by the panel manufacturer.(9)
Nail 6"o.c. along supported panel edges and 12"
o.c. at intermediate supports with 6d common nails of panels 1/2" and less, and 8d
for greater thicknesses.(10)(12) |
