Hardwood Floors February/March 2017

AT THE SITE

Subfloor Focus: Minimizing Moisture (Continued)

OTHER BENEFITS OF THESE TYPES OF VAPOR RETARDERS MAY INCLUDE:

• Elimination of wood on wood contact, making flooring strips or planks slide more easily when positioned during installation

• Reduces dust and airflow from below solid wood subfloor systems

• Minimizes the impact of seasonal moisture changes from below the flooring system

Install a vapor retarder over wood subfloors before installing nail down solid or engineered flooring (unless otherwise directed by the flooring manufacturer). The vapor retarder should cover the entire flooring surface. Overlap seams a minimum of 4 inches or more as required by the manufacturer.

SOME EXAMPLES OF ACCEPTABLE VAPOR RETARDERS MAY INCLUDE:

• Asphalt laminated paper

• Asphalt saturated Kraft paper

• ASTM rated roofing felt

• Some foam padding may be acceptable vapor retarders under floating wood floors, when meeting the above perm rating requirements (.7<10), but are never recommended under nail down applications

This chart provides an overview of acceptable vapor retarders, based on flooring type and installation method. Remember that these are presented as a guideline and that flooring manufacturer recommendations should always be followed when provided.

FLOORING TYPE INSTALLATION METHOD

ACCEPTABLE VAPOR RETARDER

Membrane (i.e., saturated or laminated, felt or paper)

Solid

Nail down or staple down

Roll or sheet membrane (i.e., min. 6 mil poly C & A film or superior ASTM D1745 mem- brane, foam pad, vented or other membrane)

Engineered

Floating

Membrane (i.e., saturated or laminated, felt or paper)

Engineered

Nail down or staple down

Proper use of an underlayment material will help you control moisture migrations from below the installed flooring. As always, check with your manufacturer for proper use, capability and installation of the product. Roger Barker is Market Manager Flooring at Fortifiber Building Systems Group in Fernley, Nevada. He can be reached at rbarker@fortifiber.com.

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