Proper Installation Of Roof Underlayment

Start by laying asphalt felt or other underlayment over the roof.

Proper installation of roof underlayment.

Although this seems to contradict the overlapping principle installing the drip edge over the underlayment at the rakes creates a clean roof edge and provides the underlayment attachment with increased resistance against wind uplift. When going up the sloped edges of the roof called the rakes it goes on top of the underlayment. If it gets wet it will wrinkle making it harder to shingle. Underlayment flashings and shingles all work together and must be installed in the correct order.

Installing roof felt is a two person job. Hammer down any large nails that are exposed by the removal. Start at the bottom side of the gable and overlap the sections of drip edge a few inches as you work your way up the roof see figure a. Install a layer of roofing insulation as recommended by the roofing manufacturer.

Install the drip edge on the gable ends of the roof after you finish installing your underlayment. Overhang the roof rake edge 1 5 and cover the underlayment with a metal rake edge trim. Nail metal drip edge flashing which bends over the roof and down the edge of the facing board on all roof edges. Do not use felt as a temporary protection against rain.

Start from the top of the roof and remove the old shingles along with the flashing underlayment and vents. The best time for installing roof underlayment is when the temperature is between 40 to 85 degrees fahrenheit. It s not ideal to install roof underlayments when the temperature is under 40 degrees f as it won t ensure a proper fit. If you live in an area with inclement weather you should consider using a special ice and water protector.

Press the membrane of the self adhering roofing underlayment in place with heavy hand pressure to ensure the desired adhesion to the roof deck. It is important to apply pressure to secure adhesion to the deck and to smooth out any wrinkles in the membrane that may result in air channels or tears that could result in a failure. Using your staple gun secure the felt to the roof. Overlap each row at least 3 to 4 inches.

Use a tin snips to cut the drip edge to size. Inspect the underlying roof sheathing for damage and make any needed repairs. If you lay the felt perfectly straight you can use its lines instead of horizontal chalklines to align the shingles. Ideally the roof covering material would be installed as soon as possible but in reality the roof may be protected by only the underlayment for days weeks or sometimes months.

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.