A. Wood flooring contractor and consultant Howard Brickman responds: Rosin paper, bad; 15- and 30-pound asphalt-saturated felt, good. Installers love red rosin paper because it is really cheap and easily covers up the dusty subfloor, making it easier to slide the wood flooring into position during installation. But those reasons don't have anything to do with the quality of the completed wood floor.
Asphalt-saturated felt, on the other hand, performs a number of functions: It retards the flow of moisture from the underside; it increases friction between the bottom of the flooring and the surface of the subfloor, resisting lateral movement during shrinking and swelling; and it provides some adhesion between the bottom of the flooring and the...
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