Permability Of Roofing Paper

Notes to the table above.

Permability of roofing paper.

Among the most vapor permeable of exterior sheathings. The research performed indicates that nonbreathable. The vapor permeance of grade d paper is similar to asphalt felt. 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.

Necessary to protect the roof sheathing from moisture within the home. Some grade d pape. Tar paper keeps the wood beneath it dry. 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.

Fiberboard asphalt impregnated. Thin profile structural sheathing. Fs 148 sd 137. At saturation marginal increase in permeability 2 8 3 4 perms.

Grade d building paper is an asphalt impregnated kraft type paper similar to the backing on fiberglass insulation. Tar paper has been time tested as a weather barrier. Its most common use is under stucco in the western united states. Fs 75 ap 0 82.

Find below the technical bulletins papers standards used as sources for these perm ratings. When then used with asphalt shingles especially traditional 3 tab shingles it sometimes telegraphs the ripples through the finished product. Unlike asphalt felt it is made from new wood pulp rather than recycled material. Normally used on roofs tar paper makes a great barrier for the exterior walls of your housing building or shed.