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.

Permability of roofing paper.

Some grade d pape. Find below the technical bulletins papers standards used as sources for these perm ratings. Permeability 14 20 5 perms. Fiberboard asphalt impregnated.

Its most common use is under stucco in the western united states. The research performed indicates that nonbreathable. Fs 75 ap 0 82. At saturation marginal increase in permeability 2 8 3 4 perms.

Tar paper keeps the wood beneath it dry. More information more information. Among the most vapor permeable of exterior sheathings. Unlike asphalt felt it is made from new wood pulp rather than recycled material.

Thin profile structural sheathing. Necessary to protect the roof sheathing from moisture within the home. 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. Notes to the table above.

Tar paper has been time tested as a weather barrier. Fs 148 sd 137. The vapor permeance of grade d paper is similar to asphalt felt. 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.