Wood Siding Weather Protection: Don't Get Caught in the Rain without It

Abstract

WITHIN THE CONSTRUCTION industry, considerable disagreement exists with regard to the choice of an appropriate building paper for use beneath wood siding and shingles in light-frame wood construction. Asphalt-impregnated felt papers, spun-bonded polyethylene, perforated high-density polyethylene films, &dquo;water-resistant&dquo; sheathings, and red rosin felt papers all have their advocates. Unfortunately, building designers frequently specify some of these products that subsequently prove to be incapable of resisting water penetration. A few designers even insist that wood siding alone forms a weatherproof barrier and that you shouldn’t need to install building paper if you have a &dquo;good coat of paint.&dquo; Surface-sealed cladding systems eventually, if not initially, allow water to penetrate beyond the surface layer. Wood siding is no exception. Building paper for application beneath wood siding must be capable of retarding the migration of liquid water before it damages interior finishes and concealed wall components. Manufacturers’ claims and laboratory water test results