Good preparation will have a direct impact on the quality of the installation and your satisfaction with the finished product. Here are some important things to keep in mind:
Site preparation
Installing the hardwood flooring should be the very last step in the process. Before the flooring is delivered, inspect the installation site and make sure that:
• All concrete, plaster, paint, and subfloor is completely dry.
• Any heating, ventilation, or air conditioning systems are functional and running.
Moisture requirements differ slightly depending on the type of flooring being installed. Here's what you should be looking for:
Solid wood flooring
The indoor temperature should be about 68°F (20°C) and the relative humidity should be around 45%.
The installer must check the moisture content of the subfloor (plywood or OSB) at various locations using a wood moisture meter. The moisture content of the subfloor must never exceed 12% and the difference in moisture content between the subfloor and flooring must not exceed 4% (internal moisture of the boards will be between 6% and 9%). If the moisture content of the subfloor or the difference between the flooring and the subfloor is too high, heat, ventilate, and dehumidify the site and delay delivery and installation of the flooring. For boards that are 4" or more in width, the difference in moisture content between the subfloor and the flooring must not exceed 2%.
Engineered wood flooring
The indoor temperature should be about 68°F (20°C) and the relative humidity should be around 45%.
The installer must check the humidity of the subfloor (plywood or OSB) at various locations using a wood moisture meter. The moisture content of the subfloor must never exceed 12% and the difference in moisture content between the subfloor and flooring must not exceed 4%. If the moisture content of the subfloor or the difference is too high, heat, ventilate, or dehumidify the site and delay delivery and installation of the flooring.
If the subfloor is a concrete slab, plan to let it dry for at least 30 days to obtain a reliable moisture reading. The moisture reading on the concrete subfloor should not exceed 4%. If there is moisture, test using calcium chloride. The moisture level measured with the calcium chloride test must not exceed 3 lbs. per 1000 sq. ft. over 24 hours.
Subfloor preparation and repair
• Recommended subfloors: Sheets of 3/4" (19 mm) plywood or oriented strand board (OSB) for joists spaced up to a maximum of 19.2" (488 mm) on center. Sheets of 5/8" (16 mm) plywood for joists spaced to a maximum of 16" (406 mm) on center.
• The subfloor must be level. Repair minor surface irregularities using a sander or floor leveler (allow the leveler to dry completely before installing the wood flooring).
• The subfloor must not be more than 3/16" (5 mm) out of level over 6' (1.8 m), or 1/4" (6 mm) out of level over 10' (3 m).
• The subfloor must be structurally sound and securely fastened to the joists with flooring screws to avoid any movement of the plywood, which could lead to cracks.
• The subfloor must be clean. Remove any glue or staples and drive in all visible nails.
• For glued installation on a concrete slab, make sure the concrete is not low density (less than 3000 psi) or crumbling.