USG Fiberock Underlayment and Tile Backerboard - Manual (Page 9)

Correcting Joint Imperfections
Use D
urock
patching compound
or equivalent sparingly to fill wide
joints, repair any surface voids
and correct joint lippage (panel
edge sitting above or below
the floor plane). Carefully fill
joints wider than 1/32" and any
surface imperfections with only
enough material to infill void – do
not feather. Correct joint lippage
by applying patching compound
to low side only and feathering
to level. Allow compound to dry
completely (90 min. minimum),
then lightly sand or scrape, taking
care not to scuff panel surface;
use a flat blade to scrape away
any excess material.
Remove all debris from panel
surfaces; vacuum carefully to
eliminate excess dust and dirt.
Applying Floor Covering
Refer to floor-covering
manufacturer's
recommendations for proper
procedures. For proper trowel
selection, refer to adhesive
manufacturer's recommendation
for nonporous substrates. Follow
floor-covering and/or adhesive
manufacturer's guidelines for
setting times before allowing
traffic on the finished floor. Follow
floor-covering manufacturer's
recommendations for preventive
maintenance, cautions and
procedures.
Perimeter-Bonded, Felt-Backed
Resilient Floor Covering
Joint patching is not required
with this type of floor covering
in new construction unless
joint spaces or lippage exceed
1/32". Carefully fill joints wider
than 1/32" with only enough
material to infill void – do not
feather. Correct joint lippage by
applying patching compound
to low side only and feathering
to level. Allow compound to dry
completely (90 min. minimum),
then lightly sand or scrape,
taking care not to scuff panel
surface. Remove dust, dirt
and debris from underlayment
surface before application of
floor covering.
Wood Flooring
Underlayment
Mechanically Fastened
Wood Flooring
Fasteners must be long enough
to penetrate through F
iberock
underlayment and into subfloor.
To determine proper fastener
length, add thickness of
underlayment to length of
fastener recommended by the
flooring manufacturer. Follow
recommendations on pages
6 and 8 for underlayment
installation.
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