This information is generally applicable to most hardwood flooring. Individual manufacturers may provide instructions which vary from these, particularly in the laying of specialty floors. Always read and follow the instructions provided by the manufacturer.

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