Dormer roofs are often made of a cheaper, less durable substance than the rest of the roof. Most dormer leaks occur as the flashing deteriorates and the connection between the two roofs is weakened, leading to leaks which may cause mould, stains and damage within the walls of the house. Dormer roof repairs require some time and a few tools but are considerably cheaper than replacing an interior wall damaged from the leak.
Climb onto the roof. While there you may want to look for any shingles, woodworking or nails that may need to be replaced.
Check the caulking at the edges of the dormer for cracking or peeling. If the flashing has rusted or has come undone, it must be replaced.
Use the putty knife to remove all the caulking around the dormer. Make sure to check the shingles around the area to see if they can be lifted without breaking. It may be a good idea to have a few extra shingles in case any need to be replaced. Lift and fold the shingles away until the caulking is removed.
Remove the old flashing and pull it away from the dormer and the shingles. Clean the area once the flashing is out to assure that no rust or dirt is left behind.
Replace the flashing. Measure it and cut it to fit using the tin snips. Push it to fit flush under the folded shingles and all the way around the dormer. Nail down the flashing that does not go under the shingles, and use a generous amount of caulking or roof putty to cover the nails. If there is no need to replace the flashing, just check that it is in place around all sides of the dormer.
Place the shingles back over the flashing. If the shingles need to be replaced, make sure that nothing is left over from the old ones.
Apply caulking to seal the edge of the dormer and each shingle. Use your fingers to smooth the entire way around and make sure there are no holes or air pockets in the caulking.
Check to ensure that all the shingles are flat and nails are covered.