Installation Guide

HARDWOOD FLOORING
INSTALLATION
SUITABLE SUBFLOORS AND FLOOR PREPARATION
ON ABOVE OR BELOW GRADE CONTINUED
Avoid suboors with excessive vertical movement no more than
3/16” (4.7mm) deection. If the suboor exhibits excessive vertical
movement (deection) before installation of the ooring, it will likely do
so after installation of the ooring is complete. Indications of excessive
deection are uneven nish wear, fastener release, squeaking,
compromised or damaged locking systems, sectional contours such as
bowing or dipping in oors and uneven ooring material.
Lightweight concrete: Engineered wood ooring is not recommended
for glue down installation over lightweight concrete suboors. To test
for lightweight or acoustical concrete, scrape a coin or key across
the surface of the suboor. If the surface powders easily or has a dry
density of l00 pounds or less per cubic foot, the engineered ooring
should not be installed using the glue down method. Product can be
installed using oating installation method. For leveling and repair of
lightweight concrete, contact the lightweight concrete manufacture to
ensure correct methods are used.
Existing perimeter glued resilient vinyl and rubber tiles are
unacceptable underlayment and must be removed. Terrazzo,
vinyl, resilient tile, cork and linoleum or hard surfaces that are dry,
structurally sound and at are suitable as a suboor. As outlined
above, the surface must be sound, tight and free of paint, oil, existing
adhesives, wax, grease, dirt, and debris. Terrazzo and ceramic tile
must be scued to ensure proper adhesion.
WARNING: Do not sand existing resilient tile, sheet ooring, backing
or felt linings. These products may contain asbestos bers that
are not readily identiable. Inhalation of asbestos dust can cause
asbestosis or other serious bodily harm. Check with local, state and
federal laws for handling hazardous material before attempting the
removal of these oors.
Direct glue installation: Make sure the oor covering materials
are well bonded to the suboor or underlayment with full spread
adhesive and no more than two layers thick, not to exceed 3/16” (4.7
mm). With approved wood or wood composite suboors, if vinyl or
tiles are loose, broken or in poor condition, install a 3/8” (9.5 mm)
approved suboor panel directly over the ooring materials. Clean
the ooring materials as necessary to remove waxes, sealers or
cleaning residues to allow a good adhesive bond. Cork oor sealers
and surface treatments must be removed. Always perform a bond
test prior to beginning direct glue installation.
Moisture test is required on all suboors as outlined above and
must meet the requirements before installation takes place,
regardless of the installation method used.
Approved wood suboor panels should meet or exceed the
following guidelines:
• Plywood must be minimum CDX EXP 1 grade and conform to U.S.
Voluntary Product Standard PS2 or Canadian performance \
standard CAN/CSA 0325-0-92.
• Oriented Strand Board (OSB) must conform to U.S. Voluntary
Product Standard PS2 or Canadian performance standard CAN/
CSA 0325-0-92. The panels must be tongue and groove and
installed sealed side down.
• Particleboard must be a minimum 40-lb. density, stamped
underlayment grade and 3 ⁄4” (19mm) thick. (Floating
installation only)
Floor joist/truss spacing will determine the minimum acceptable
thickness of the suboor panels. Joist/truss spacing of 16”, up to
19.2” (488mm) on center, requires a minimum nominal 3/4” (23/32”,
18.3mm) tongue and groove CDX EXP 1 plywood or OSB 4’x8’ suboor
panels, glued and mechanically fastened. Floor systems with joists/
truss spaced greater than 19.2” (488mm) on center up to a maximum
of 24” (610mm) require minimum 7/8” tongue and groove CDX EXP
1 plywood or OSB 4’ x 8’ suboor panels, glued and mechanically
fastened. Installation over joist spans greater than 24” on center is not
recommended. For installation over joist spans greater than 24” on
center, consult NWFA for panel thickness guidance.
Solid Wood Suboor (direct glue or staple down applications):
• Minimum 3/4” (19mm) thick with a maximum width of 6” (15cm)
installed at a 45° angle to the oor joists.
• Group 1 dense softwood (pine, larch, douglas r, etc.) No. 2
common, kiln dried with all board ends bearing on joists.
• For direct glue down applications add 3/8” (9.5mm) approved oor
panel underlayment.
Existing wood ooring (direct glue or staple down applications):
• Existing engineered ooring must be well bonded/fastened.
When gluing over existing wood ooring, the surface nish must
be abraded or removed to allow adequate adhesive bond.
• Existing solid hardwood ooring that exceeds 6” (15cm) in width
must be covered with 3/8” (9.5mm) compatible underlayment and
fastened as required.
• Do not install over solid or engineered ooring attached directly to
concrete. Instead remove existing wood ooring and follow
instructions for installation over concrete.
Wood sub-oors should be well nailed or secured with screws. Nails
should be ring shank and screws need to be counter sunk. The wood
suboor must be structurally sound, without loose boards, vinyl or
tile. If suboor panels are a single layer, less than 3/4” thick, add
another single cross layer for strength and stability, minimum 3/8”.
Underlayment oor panels must be installed sealed side down. When
used as a sub-oor, allow 1/8” (3.2 mm) expansion space between
each panel. If spacing is inadequate, cut in with a circular saw. Do not
cut an expansion space on tongue and groove panels. When installing
parallel to the oor joists, it may be necessary to increase rigidity of
the structural suboor system by installing an additional minimum of
3/8” (9.5 mm) compatible underlayment oor panel.