Permability Of Roofing Paper

The research performed indicates that nonbreathable.

Permability of roofing paper.

Fs 148 sd 137. Some grade d pape. Asphalt felt is paper based and has no memory meaning once it attracts moisture by being left on the roof overnight or if it gets wet it will ripple and curl and will not lay flat once it dries. Permeability 14 20 5 perms.

Among the most vapor permeable of exterior sheathings. More information more information. Notes to the table above. When then used with asphalt shingles especially traditional 3 tab shingles it sometimes telegraphs the ripples through the finished product.

Its most common use is under stucco in the western united states. Find below the technical bulletins papers standards used as sources for these perm ratings. The focus of this paper is to investigate the system performance of standard asphalt shingles and to evaluate the impact of installing nonbreathable underlayments between the shingle layer and the roof deck. Fiberboard asphalt impregnated.

Tar paper keeps the wood beneath it dry. Grade d building paper is an asphalt impregnated kraft type paper similar to the backing on fiberglass insulation. At saturation marginal increase in permeability 2 8 3 4 perms. Grade d building papers must have a 10 minute rating under astm d779 commonly called the boat test in which a piece of building paper is folded in the shape of a boat and floated in a dish of water until it soaks through and wets a powder on top.

Fs 75 ap 0 82. Thin profile structural sheathing. The vapor permeance of grade d paper is similar to asphalt felt. Necessary to protect the roof sheathing from moisture within the home.