Vapor Permeable Roof Underlayment

A highly vapor permeable roofing underlayment air barrier ab material.

Vapor permeable roof underlayment.

Any material with a perm rating of 10 or greater is highly permeable. Or just stick with asphalt felt underlayment if you want a vapor permeable product. Roof underlayment test compliance. Todays homes are larger and more detailed than in the past making it unlikely the job will be started and completed the same day.

Underlayment works in two waves. 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. The use of asphalt felts semi permeable products has long been the underlayment of choice. They are also generally more expensive.

Typically 15 felt for asphalt shingles and 30 for wood roofing were the common practice. Slopeshield plus self adhered sa a vapor permeable roofing underlayment is designed for use on steep slope roofs of 2 12 or greater pitch. According to the manufacturer the roofing underlayment features the patent pending vapor permeable polymer composite technology vppct developed by vaproshield. Is managed across these two different underlayment systems.

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. The first period is critical. The second period is after the new shingles have been applied. Synthetics are manufactured with a vapor permeance that can be as high or higher than asphalt felt underlayment.