Vapor Permeable Roof Underlayment

They are also generally more expensive.

Vapor permeable roof underlayment.

Is managed across these two different underlayment systems. Synthetics are manufactured with a vapor permeance that can be as high or higher than asphalt felt underlayment. Or just stick with asphalt felt underlayment if you want a vapor permeable product. When all of your old shingles are removed the underlayment is rolled on to protect the exposed roof from elements until the new shingles can be applied.

Underlayment works in two waves. Follow up simulations showed if time aged roof shingles deteriorated and water penetration occurred onto the underlayment substantially higher moisture accumulation in the osb occurred for the vapor permeable underlayment. According to the manufacturer the roofing underlayment features the patent pending vapor permeable polymer composite technology vppct developed by vaproshield. Typically 15 felt for asphalt shingles and 30 for wood roofing were the common practice.

The underlayment continues to act as another layer of protection. The use of asphalt felts semi permeable products has long been the underlayment of choice. The second period is after the new shingles have been applied. Promotes long term drying of roofing assembly through vapor diffusion.

Roof underlayment test compliance. Any material with a perm rating of 10 or greater is highly permeable. The first period is critical. Slopeshield plus self adhered sa a vapor permeable roofing underlayment is designed for use on steep slope roofs of 2 12 or greater pitch.