USG Fiberock Underlayment and Tile Backerboard - Manual (Page 6)

Cutting Panels
Maintain temperature and
humidity in space approximate to
that of normal occupancy prior to,
during and after installation.
Install underlayment, with
fastener marks up. Panels may
be cut by scoring and snapping
with a utility knife and straight
edge, or by sawing, working from
the face side. With score-and-
snap method, score panel twice
and snap away from cut face,
then snap panel in reverse
direction to break the back.
Where necessary, use a rasp or
surform to smooth the cut edges.
Cutouts
For difficult cuts, combine the
score-and-snap method with use
of a handsaw or low-RPM power
saw. Cut holes for plumbing
with a hole saw, keyhole saw or
variable-speed jigsaw. A power
saw should be used only if
equipped with a dust-collection
device. Always wear an OSHA-
approved dust mask when
cutting F
iberock
panels with a
power saw.
For more cutting techniques,
consult your USG F
iberock
representative.
Panel Layout
Lay cut edges against the wall—
only factory edges should be
joined. Begin laying panels
at one corner. Maintain 1/4"
space between panels and
perimeter walls. Stagger joints
a minimum of 16" so that four
panel corners never meet, and
offset end and edge joints of
panels a minimum of 12"–16"
from subfloor panel joints. Butt
panel edges and ends lightly
together. A maximum 1/32"
gap is allowed.
Preparation for resilient
flooring: Consider critical lighting
when determining panel layout.
Run continuous panel joints in
the direction of the dominant
source of natural light, when
possible.
Prior to installation of final
floor covering, avoid heavy traffic
and moving heavy items across
panels. If necessary, items
such as refrigerators or other
appliances with wheels (or on
wheeled dollies) may be rolled
over underlayment surface; using
strips of hard wood or scrap
underlayment to bear the wheel
traffic is recommended. Allow
a minimum of 24 hours after
floor covering installation before
placing heavy appliances or
furniture on floor.
Cutting and
Laying Out Panels
6
16" 16"
1/4" gap
cut
edge
factory edges
underlayment
subfloor
F-119 Placing Fiberock brand Panels