Installation Instructions

Preparation
Crawl-Space Requirements
Crawl-space requirements
may vary based on
geographic location. Consult
local building codes for more
specific information regarding
vapor barriers and their uses.
Subfloor Requirements
The subfloor system should be
designed for a deflection limit
of L/360 for the span. The
subfloor should be APA Span-
Rated Plywood or OSB with
an Exposure 1 classification
or better with tongue and
groove or back-blocked at the
unsupported edges.
Resilient Flooring
Joist Minimum
Spacing Subfloor
Thickness
16", 19.2" 23/32"
and 24" o.c.
Ceramic Tile
Joist Minimum
Spacing Subfloor
Thickness
16" o.c. 19/32"
19.2" o.c. 23/32"
24" o.c. 23/32"
Wood Subfloor
flush with or slightly
below surface
sand uneven
joints
fill and
sand gaps
Clean subfloor and leave free
of dust, dirt and debris. Ensure
that subfloor is completely dry
(no more than 12% moisture in
subfloor prior to install). Verify
that fasteners are flush with,
or slightly below, subfloor
surface.
Ensure that subfloor and
structure are within tolerances
specified by floor covering
manufacturer. Inspect subfloor
for even, flat surface before
installing underlayment.
Uneven end edge joints and
variations in subfloor panel
thickness may telegraph
through underlayment in vinyl
applications. Sand uneven
joints, if necessary.
Ensure that subfloor is flat
between framing elements.
If subfloor panels appear to
buckle, correct by adding
blocking or cleats under floor.
Fasten cleats to subfloor to
flatten panels. Repair voids,
large gaps and penetrations
through subfloor using a
manufacturer-approved floor
leveler prior to installing USG
Fiberock underlayment.
Over Existing Vinyl Floor
CAUTION: Do not install USG
Fiberock underlayment over
heavily cushioned, thick foam-
backed floor coverings.
– Ensure that existing floor is
level and meets appropriate
design requirements.
– Repair any missing or
broken vinyl tiles, curling
seams, severe gouges, or
protrusions by filling with
floor leveler.
If floor will be finished with
ceramic tile, make sure that
the existing vinyl covering is
fully adhered and bonded to
the floor.
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