Roof Underlayment Overlap

In steep slope roofs 4 12 and steeper the upper courses of felt underlayment should overlap lower courses by at least 2 inches.

Roof underlayment overlap.

Roofing underlayment roofing felt requirements. Felt details for various roof slopes amp. Two ply roofing underlayment typically overlaps by half the width of the roll plus one inch for headlap. That s half the width of the roll plus one inch for headlap.

Subscribe and share please. Continue along the roof to the other end and trim the felt flush at the end with a utility knife. Video of the day. Synthetic roofing underlayment is to be laid horizontally parallel to eave with printed anti slip side up starting at the bottom of the lowest roof eave with a 1 5 underlayment overhang at the eave covering the pre installed eave drip edge.

This article series discusses roofing felt specifically addressing the roofing code or roofing manufacturer s requirements for use of an underlayment such as roofing felt tarpaper or other underlayment products beneath asphalt shingles and other. Therefore a 2 inch overlap provides redundancy at the edges where the barrier is weakest. Overhang the roof rake edge 1 5 and cover the underlayment with a metal rake edge trim. Wide the material needs to be overlapped a minimum of 19 in to achieve full double coverage.

Residential and commercial roofing shingles slate roof ventilation roof underlayments asphaltic and tpo roof membranes. Some contractors prefer the back roll method. Check this out. You can see the difference between the underlayment overlapped 19 inches on the roof to the right and overlapped 2 inches on the roof to the left.

By comparison the standard overlap for single ply underlayment is only 2 inches at horizontal laps and 4 inches at vertical laps. The overlapping felt creates a secondary barrier for moisture and wicks water away from the shingles above and the sheathing below. Gcp applied technologies grace ice water shield roofing underlayment requires side laps to be a minimum of 90 mm 3 5 in and end laps a minimum of 150 mm 6 in. Roofing shingles and materials plus factory certified roofers including ratings from real homeowners from north america s largest roofing manufacturer.

How to install roofing underlayment the proper way. Headlap is the amount of lap over the top of the course two below. The headlap is narrow band of 3 ply coverage at the top of each lap as shown in the illustration. Roofing felt is required to overlap 2 inches over the lower felt course.

Overlap the end of a roll about 4 inches with the start of a new roll and fasten both pieces to the. Is roofing felt required. Minimum overlap guidelines are set by the manufacturer.