Roofing Felt Overlap Size

The overlapping felt creates a secondary barrier for moisture and wicks water away from the shingles above and the sheathing below.

Roofing felt overlap size.

The vertical leg of the drip edge should be at least 1 5 inches wide and extend at least 0 25 inches below the sheathing. Therefore a 2 inch overlap provides redundancy at the edges where the barrier is weakest. In most cases this will leave 400 square feet 37 m 2 of net coverage per 1 roll. One roll of conventional 15 felt covers 432 square feet 40 1 m 2.

Convert the area from inches to feet prior to purchasing your felt. The drip edge should extend at least 2 inches on the roof. Adjacent pieces of drip edge should overlap at least 2 inches 51 mm. Never walk on felt that has not been nailed down.

Roll out the felt no more than midway perhaps 25 feet or so across the average size roof. If there is any wind at all roll out the felt only about 10 feet. Roofing requirements roofing felt is required to overlap 2 inches over the lower felt course. In steep slope roofs 4 12 and steeper the upper courses of felt underlayment should overlap lower courses by at least 2 inches.

The spacing between the nails on the drip edge should be less than 12 inches apart. Purchase enough felt to cover your roof s area. 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. Continue along the roof to the other end and trim the felt flush at the end with a utility knife.