How Much Should Roofing Felt Overlap

Therefore a 2 inch overlap provides redundancy at the edges where the barrier is weakest.

How much should roofing felt overlap.

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. Using a downwards brushing motion firmly press the top layer of roofing felt onto the adhesive taking care to ensure that the strip of felt does not ripple or crease. The felt must be flush at the rake side edges have 4 inch overlaps where two pieces are joined and 6 inch overlaps on hips and ridges.

Since you will have overlap between rows this works out to a total coverage area of 400 square feet the dimensions of a 20 x 20 roof. Some roofing felts are actually glued down. The overlapping felt creates a secondary barrier for moisture and wicks water away from the shingles above and the sheathing below. One roll of conventional 15 felt covers 432 square feet 40 1 m 2.

However you must allow for overlaps on joints. These applications are ideal for flat roofs or protective surfaces under roof level decks. Nail along the top of this strip at 500mm. 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.

Ensure that the felt lies flat and smooth before securing it. In other words if the height of the roof drops by 2 inches for every 12 inches in length you will need to use sealant to strengthen the overlap barrier. Purchase an extra pack of felt in case you need more or end up damaging your first roll. Position this strip so that it overhangs the top of the first sheet by 75mm.

Do the other side of the roof the same way also with an overlap at the peak. Work up the roof to the peak and fold felt over the top overlapping at least 3 inches and fasten it on both sides. Trapped behind the guttering or if it is badly weathered it needs to be replaced. A conventional roll of felt is enough for 432 square feet.

Where the sheets overlap apply roofing sheet adhesive using a disposable brush. If this felt is either incorrectly situated i e. Make sure you have enough roof felt you don t want to have to stop mid way through the project to buy more felt. If lap sealant is used simply apply a bead of sealant on top of the underlap ridge going all the way down the length of the ridge before the overlap ridge of the next panel is placed on top.

In most cases this will leave 400 square feet 37 m 2 of net coverage per 1 roll. The overlap of 3 8 should be followed consistently for a smooth look once the shingles are installed. Take your second length of felt. Roofing felt is required to overlap 2 inches over the lower felt course.