Permability Of Roofing Paper

Find below the technical bulletins papers standards used as sources for these perm ratings.

Permability of roofing paper.

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. The research performed indicates that nonbreathable. Notes to the table above. Some grade d pape.

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. Among the most vapor permeable of exterior sheathings. When then used with asphalt shingles especially traditional 3 tab shingles it sometimes telegraphs the ripples through the finished product. The vapor permeance of grade d paper is similar to asphalt felt.

Its most common use is under stucco in the western united states. Thin profile structural sheathing. Unlike asphalt felt it is made from new wood pulp rather than recycled material. 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 148 sd 137. Tar paper keeps the wood beneath it dry. At saturation marginal increase in permeability 2 8 3 4 perms. Fiberboard asphalt impregnated.

Necessary to protect the roof sheathing from moisture within the home. Permeability 14 20 5 perms. Fs 75 ap 0 82. More information more information.