Job Site Preparations for Hardwood Flooring
Hardwood is a living substance which reacts to changes in relative
humidity. Wood gains and loses moisture before and after installation,
as surrounding conditions fluctuate. Indeed, wood expands in the
summer when humidity level is high and contracts in the winter when
the humidity level is much lower. To minimize the expansion or contraction
of your hardwood floor, it is recommended that the building should
be well ventilated and the relative humidity level maintained at
45% all year long.
The building should be closed in with outside windows and doors
in place. All concrete, masonry, sheetrock and framing members,
etc. should be thoroughly dry before the flooring is delivered to
the job site. In warm months the building must be well ventilated;
during winter months heating should be maintained near occupancy
levels at least five days before the flooring is delivered and until
sanding and finishing are complete.
Basements and crawl spaces must be dry and well ventilated. In
joist construction with no basement, outside cross ventilation through
vents or other openings in the foundation walls must be provided
without dead air areas. A surface cover of 6 mil polyethylene film
is essential as a vapor in crawl space construction.
Because materials used to provide energy efficient structures
trap moisture in a residence, it may be necessary to delay delivery
and installation of flooring to allow the excessive moisture trapped
during construction to evaporate. The average moisture content of
framing members and sub-flooring should be below 12%-14% before
delivery of the flooring. Moisture contents above 12%-14% can cause
moisture related problems. Using a hygrometer, verify the sub-floor
(plywood) humidity level; it must not exceed 12%. If the humidity
level is too high, turn up the heat and open the basement windows
less than an inch.
Be sure to maintain occupancy-level temperature and humidity for
at least five days prior to installation. From the time flooring
is delivered and until occupancy, temperature and humidity should
be maintained at or near occupancy levels.
When job site conditions are satisfactory, have the flooring delivered
and broken up into small lots and stored in the rooms where it will
be installed. Allow 3 to 5 days or more, for the flooring to become
acclimated to job site conditions. If flooring is packaged, open
or remove packaging for acclimation.
Remove baseboards and door sills, screw the sub-floor securely and
if applicable to your installation, apply a double layer of 15 lb
or a single layer of 30 lb asphalt felt or building paper. Using
a handsaw, slit the bottom of the door-frames 3/4" in order to slide
a hardwood plank beneath the door.
Recommended Tools and Materials
Job Site Preparations • Installation • Maintenance • Professional Tips • Installing Over Concrete • Installating Over Radiant Heat • Installation Booklet (pdf 338kb)