Roofing Felt Vs Vapor Barrier

Today glass fiber or polyester fabric may be used instead of paper.

Roofing felt vs vapor barrier.

Roofing shingles and materials plus factory certified roofers including ratings from real homeowners from north america s largest roofing manufacturer. House wrap and felt paper when properly installed and undamaged are both weather resistant barriers wrb that create permeable and water and air resistant exterior walls. The underlayment provides a secondary weather barrier against wind driven rain and snow. Also known as tar paper roofing felt originated in finland in the 1870 s as a waterproofing underlayment for roofs.

What is roofing felt. Residential and commercial roofing shingles slate roof ventilation roof underlayments asphaltic and tpo roof membranes. Asphalt felt and synthetic underlayments are products installed under all the roofing materials and directly on a roof deck. Felt is commonly sold in either 15 or 30 rolls measuring 36 inches wide.

When and why condensation occurs inside buildings explains the problems caused by excessive indoor condensation explains how moisture enters building wall and ceiling cavities. Adding other materials on top of the felt paper could radically change the felt paper s ability to transfer water vapor back out to the atmosphere you bet it can be you may want to know if felt paper is a vapor barrier or vapor retarder. The shingles are the primary weather barrier. The vapor permeance of grade d paper is similar to asphalt felt and it blocks liquid water effectively in tests for anywhere from 10 to 60 minutes.

Generally speaking roofing felt is a felt paper that is soaked in asphalt and other water resistant compounds to produce a membrane. A gypsum fiber board has a perm rating of approximately 24 to 30 perms depending on thickness and if this board is fastened to a steel deck and the joints and transitions are taped it could be an effective air barrier that allows some drying. The use of roofing felt or 15 pound felt as a building house wrap or vapor barrier and the permeability moisture problems and indoor condensation problems that may occur vapor barriers and condensation in buildings. Later asphalt was used in the manufacture of roofing felt.

The main advantage of house wrap over felt paper is the superior strength and durability of house wrap. The choice of 15 or 30 pound felt paper is up to you. Of course it is a bit more technical than that but this is the basic idea behind how felt works. Grade d paper is commonly use is under stucco in the western united states.

Unlike asphalt felt it is made from new wood pulp rather than recycled material. Another option for the roofing system is to recognize a hardboard or sheathing layer can be a vapor open air barrier.