Installation Guide

Document ID#: MWPHF061720_SOLID
SOLID HARDWOOD FLOORING IS NOT APPROVED FOR INSTALLATION
OVER RADIANT OR IN-FLOOR HEATING SYSTEMS
Keep flooring dry, flat, and maintain good air circulation in storage. RECORD
SUBFLOOR AND FLOORING MOISTURE CONTENT UPON DELIVERY AND AT
TIME OF INSTALLATION AND RETAIN THESE RECORDS.
Acclimate Solid Hardwood Flooring to controlled site conditions; refer to NWFA
Installation Guidelines, Sec. I, Ch. 2 for detailed information.
HVAC must be in operation before, during, and after installation (refer to NWFA
Installation Guidelines, Sec. I, Ch. 1, Part 1). A temperature of 70 degrees F +/- 10
degrees and a relative humidity between 30-50% is recommended. Heating units or
uninsulated ductwork close to the flooring or subfloor may cause “hot spots” which
must be eliminated prior to installation.
Moisture testing is critical (refer to NWFA Installation Guidelines, Sec. I, Ch. 3).
Confirm proper drainage exists around the structure. In crawl spaces, exposed earth
must be fully covered with minimum 6-mil polyethylene sheeting. Crawl space vents
must be open at all times and must equal at least 1.5% of the total square footage of the
crawl space. Basements must be dry and remain dry.
Subfloor Types and Conditions (NWFA Installation Guidelines, Sec. II)
General:
The subfloor must be clean, dry, flat (within 3/16” in 10’), and structurally sound.
Correct any joints or areas that are not flat. Secure any loose boards or panels.
Wood: (refer to NWFA Installation Guidelines, Sec. II, Ch. 4)
CD Exposure 1 plywood and OSB Exposure 1 subfloor panels are appropriate subfloor
materials (grade stamped US PS1-95). Solid board subfloors should be 1” x 6” nominal,
Group 1 dense softwoods, #2 Common, KD. Minimum single layer subfloor thickness is
5/8” for plywood panels and ¾” OSB on 16” O.C. Joists or 3/4” on 19.2” O.C. Joists and
7/8” on 24” O.C. Joists. Particle board panels will not properly hold fasteners and no
claim with regard to noise when walked upon will be accepted. The flooring must run
perpendicular to the floor joists, or additional subfloor thickness is required (1/2”
plywood or equivalent product). Hardwood flooring should be between 6 and 9%