Wood Floor Installation - Sub-Floor Preparation

Before beginning your hardwood floor installation, it's essential that you thoroughly clean the subfloor. Remove all paint, oil, grease, sealers, drywall patch, dirt, adhesives, or any other contaminates.

The sub-floor must be dry
Concrete must be cured for at least 60 days and visually dry with no history of moisture problems. When testing for moisture, it's suggests utilizing the industry-standard calcium chloride test or the Tramex Moisture Encounter (5% max). Wood, OSB, or plywood sub-floors must be 14% maximum.

The sub-floor must be level (flat)
Check the sub-floor to determine that it is level to within 3/16" in a 10 ft. radius, or 1/8" in a 6 ft radius. (Loose or hollow spots in a hardwood floor are mostly due to uneven variations in the sub-floor.) Fill low areas with high-compression, latex-based Portland leveling patches, adhering to the manufacturer's guidelines. Sand or grind high areas.

The sub-floor must be structurally sound
There must be no light-weight concrete under 100 lb. Test Cured. The floor joist must be no more than 16" on center, or the floor must be reinforced by adding additional underlayment or using cross-blocking. Crawl spaces must have the soil covered (6 mil. black poly) and must allow open ventilation of 1.5% for the total floor area. OSB must be APA-rated and maintained in a controlled environment, before and after installation, and not exposed to excessive moisture. Underlayment-grade particleboard can only be used as a subfloor if you are performing a glue-down installation of engineered wood flooring. If the sub-floor is radiant-heated, you must install engineered or longstrip flooring only.

Acclimate pre-finished hardwood floor according to the following:

• Solid - 72 hours
• Engineered - 48 hours
• Longstrip - No acclimation required
• Allow an additional 24-hours acclimation time in very dry or humid areas.

Flooring	Installation Method	Requirements
Solids	Nail/Staple	On/Above Grade only Expansion Space - 3/4", length 1%, crossgrain 15% Acclimate 72 hours minimum
Engineered	Glue Staple Nail	All grade levels allowed Mix cartons Expansion space - 1/2" Acclimate 48 hours minimum
Longstrip	Glue Float	All grade levels allowed Mix Cartons Expansion space: 1/2" No acclimation required