Checking for moisture inside and out
by National Wood Flooring Association (NWFA)

Before flooring can be installed, the new construction or renovation project must be very close to completion. All excessive building moisture must be eliminated.

Ensuring that moisture conditions are met means the building must be roofed, walled and windowed, and the heating and air conditioning units should be operating. Ideally, a flooring installation should proceed only after the interior atmospheric conditions are established at Normal Living Conditions.

Here is a checklist for clues for potential sources of moisture:

• On new construction or existing house, check blueprints for landscape details. "It's recommended a 6% slope first 10ft from the house. Also from experience - easilly overlooked= nearby hillside to the house"
  
• Check the eave overhang on the building. Is all rain water funnelled away from the foundation?
  
• Is the site properly graded to divert water away from the foundation?
  
• Check the gutters and downspouts. Is all rain water properly diverted away from the foundation? During a rain, the depressions below the spouts can fill with water that will eventually find its way indoors.
  
• Are there raised flower beds or planter boxes adjoing the building's foundation? If so, a special moisture membrane should be installed. Are landscape sprinklers directed away from the house?
  
• Is there an outdoor pool or body of water elevated above home's foundation that could overflow or leak into the home's foundation?
  
• In a crawl space, the square footage of the perimeter vents through the foundation should be equal to 1.5 percent of the square foot area within the crawl space? Vents must be open to allow proper cross ventilation?
  
• Is the soil within the crawl space properly covered with 6- to 8-millimeter black polyfilm moisture barrier?
  
• Do outside doors and windows appear to be properly caulked and weatherproofed?
  
• Is the concrete slab's moisture level suitable for installation? Conduct a moisture test before installation.
  
• Is there a 6-mil polyfilm moisture barrier or equal beneath the slab?
  
• Are all major appliances and systems properly vented to release warm, moist air? Visually inspect plumbing in the area where the floor is to be installed.
  
• Is there a sense of damp, moist or stagnant air when entering the home? If so, the situation must be corrected.
  
  
• Are the heating and air conditioning operational?
  
• Temperatures of the subfloor, adhesives and flooring should be over 60 degrees Fahrenheit during installation. Check manufacturer's recommendations.
  
• What is the moisture content of the subfloor and what is the relative humidity of the jobsite?
  
  
• What is the condition of the subfloor? Is it over wood joists or slab? If it's over wood joists, what is the thickness of the subfloor? Is the subfloor approved for wood-flooring application?