|
HARDWOOD FLOORING INSTALLATION GUIDE |
|
Job Site Conditions
Check the jobsite before delivery. Be sure the flooring will not be exposed to excessive periods of high humidity
or moisture. The surface grade or slope should direct water away from the building.
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 with no dead air areas. A surface cover of 6 mil polyethylene film is
essential as a vapor retarder in crawl space construction.
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 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.
When job site conditions are satisfactory, have the flooring delivered and broken up into small lots and stored in rooms where it will be installed.
Allow 4 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.
Protect flooring from excessive heat. Flooring installed over a heating plant or un-insulated heating ducts may develop cracks unless protection
from the heat is provided. Use a double layer of 15 lb., or a single layer of 30 lb. asphalt felt/building paper, or ½" standard insulation
board between joists under the flooring in these areas. Over a heating plant the insulation used should be non-flammable.
Installations Over a Concrete Slab
Hardwood flooring can be installed successfully over a slab which is on-grade or above grade. Below grade installations are not
recommended. The slab must be constructed properly (dry and flat with a trowel finish).
Watch out for water. New concrete is heavy with moisture, an inherent enemy of wood. Proper on-grade slab construction requires a vapor retarder
such as 6 mil polyethylene film between the gravel fill and the slab. While this prevents moisture entry through the slab, this membrane also retards
curing of the slab. So test for dryness, even if the slab has been in place over two years. Slabs younger than 60-days are generally too wet for flooring
installation.
Testing Concrete for Excessive Moisture
NOTE: Make test in several areas of each room on both old and new slabs. When test indicates too much moisture in the slab, do not
install hardwood floors. For a moist slab, wait until it dries naturally, or accelerate drying with heat and ventilation then test again.
- The Rubber Mat Test. Lay a smooth, non-corrugated rubber mat on the slab, place a weight on top to prevent moisture from escaping, and allow
the mat to remain 24 hours. If the covered area shows water marks when the mat is removed too much moisture is present. This test is worthless if the
slab surface is other than light in color originally.
- The Polyethylene Film Test. Tape a one-foot square of 6 mil clear polyethylene film to the slab, sealing all edges with plastic moisture resistant
tape. If, after 24 hours, there is no "clouding" or drops of moisture on the underside of the film, the slab can be considered dry enough to install
wood floors.
- The Calcium Chloride Test. Place a quarter teaspoon of dry (anhydrous) Calcium Chloride crystals inside a 3-inch diameter putty ring on the slab.
Cover with a glass so the crystals are totally sealed off from the air. If the crystals dissolve within 12 hours the slab is too wet.
- The Phenolphtalein Test. Put several drops of a 3% Phenolphtalein solution in grain alchohol at various spots on the slab. If a red color develops
in a few minutes, too much moisture is present.
Slab Preparation
The slab must be sound and flat. To prepare the slab grind off any high spots, fill low spots, clean up grease, oil and other contaminants,
and sweep clean. If the slab is "mealy" and excessively dusty, it may not be of proper strength.
Vapor Retarder
To be certain normal slab moisture does not reach the finished floor, a proper vapor retarder must be used on top of the slab. Where this
is placed will depend on the type of system used. The vapor retarder should have a U.S. perm rating of less than 1 perm. 6 mil polyethylene film has a
0.04 perm rating and is considered a good choice.
With ¾" plywood used as a nailing base, the recommended vapor retarders are affixed to the slab. These systems may be either 2 membrane asphalt
felt/building paper and mastic or a 4-6 mil polyethylene film or an equivalent system as described below.
Two membrane asphalt felt or building paper system. Prime and apply cold cut-back asphalt mastic with a notched trowel at the rate of 50 sq. ft. per gallon.
Let set 2 hours. Roll out 15 lb. asphalt felt/building paper, lapping edges 4". Butt ends. Over this apply a second similar coating of mastic and roll out
a second layer of asphalt felt/building paper. Lay both layers of felt in the same direction, but stagger the overlaps to achieve a more even thickness.
Polyethylene method. When slabs are well above grade and the expected annual rainfall is light to moderate, cover the entire slab with 4- to 6-mil polyethylene
film, overlapping edges 4-6" and allowing enough to extend under the baseboard on all sides.
Where moisture conditions are considered more severe prime and apply* cold-type cut-back asphalt mastic with a straight-edge
or fine tooth trowel over the entire slab surface ( 100 sq. ft. per gal.). Allow to dry about 1 hour. Lay the 4-6 mil polyethylene film over the slab, covering
the entire area and lapping edges 4-6". "Walk in" or roll in the film, stepping on every square inch of the floor to insure proper adhesion. Small bubbles are
of no concern, and may be punctured to allow captive air to escape.
| * - Always follow manufacturer's instructions |
Next Page |
| 
