Examine the area
Carefully inspect the area surrounding the roof pipe. Try to gauge exactly where the leak has sprung. The leak can be happening either from the pipe-boot flashing or from around the pipe. Once you have detected the exact source of the trouble, you can then undertake the required measures to rectify the problem.
Pull out the nails
Start by removing all the shingles surrounding the vent with the help of a shingle scraper. Take out all the nails, holding the shingles to its surface. Begin with shingles closest to the vent before working your way to the surrounding area. Once the surface is clear of the shingles, prep the area for further repair work. Scrub the spot with a steel-wool pad to remove debris and smoothen the surface for new shingles.
Measure the surface
Next, measure the area surrounding the vent to determine the exact amount of flashing required. Mark down the size and cut the flashing appropriately either with a utility knife or with a heavy-duty scissor.
Fix the flashing
Glue the flashing to the surface with adhesive. To prevent gaps from occurring, overlap the flashing around the roof vent. Apply pressure to secure the flashing firmly to the vent. Use an adhesive that has been specifically recommended by the retailer.
Watertight the seal
Just applying adhesive is not sufficient to secure the flashing; you need to seal it further to protect against the harsh climatic conditions. In order to create a waterproof seal, try applying a layer of asphalt cement around the vent and flashing. Let the cement dry off completely before continuing work on the vent.
Trim the new shingles to fit the vent using a utility knife. Follow the manufacturer’s guidelines precisely when replacing the shingles. Secure the shingles to the spot using galvanized nails. Start working on the right side of the singles and work your way to the bottom. Apply a dollop of roofing caulk on the nail heads until no portion of it remains visible. The roof caulk will not only cover the unsightly looking nail heads, but also prevent water from leaking through the nail shaft.
Prevent injury by following basic safety measures such as wearing safety gloves and goggles. Before climbing on the ladder, make sure you have familiarized yourself with the safety procedures involved with it. When wetting the shingles to check if it still leaks, be extremely careful, as wet shingles tends to be slippery.