How to Repair a Leaky Roof
Finding a leak and fixing it.
The hardest part of fixing a leaky roof might be finding the leak. The first sign is often a ceiling stain. To minimize ceiling damage, let standing water out by poking a few holes through the stained area. Catch the water in a pot.
Since water can travel some distance before it reaches the ceiling, the leak may be anywhere between the stain and the roof's ridge line. Check the flashings first. If the roof rafters in the attic are visible, use a flashlight to look for the leak in a rain storm or when a helper soaks the roof with a hose.
When you find moisture on a rafter trace it to it's source. On a bright day, you may even see sunlight through a hole. When you find the hole, poke a nail through so you may locate it on the outside.
If the rafters on your house are inaccessible from the inside, examine the roof itself. Look for cracks, worn areas, rust spots in the flashings, and broken or missing shingles. (Such inspections, carried out periodically, can prevent future leaks; if asphalt shingles show signs of drying and stiffening, cover them with an alcohol-based roof coating.)
Caution: Never work on a roof in wet or windy weather. Wear soft-soled shoes. Make sure the ladder is secure; on a steep roof, use a braced ladder. Plug holes and cracks in tile and slate roofs with plastic roof cement. If a tile or slate shingle requires replacement, call a professional contractor.
Replace an asphalt shingle on a warm day, when the asphalt is flexible. Gently lift the shingle above and pry out the nails that hold the bad one in place. Remove it and slip in a replacement; secure it with roofing nails.
When replacing an asphalt eave shingle, look at the inverted shingle beneath it; it may also be damaged. Before replacing a ridge or hip shingle, examine adjacent shingles for the nailing pattern; then use the bad shingle as a pattern for cutting and securing the replacement. Cut the shingle on the back, or smooth side, then bend and break it.
If a wood shingle is badly worn or split, use a hammer or small axe to demolish it in place. Pull out the pieces, then slip a hacksaw blade under the shingle above, and sever the nails as close to the surface as you can. Cut a new shingle to fit in the gap; then tap it in place until its edge is aligned with adjacent shingles. Drive a nail in the center of it and dab the nail head with roofing cement.
If a bubble or blister forms on a flat roof, slit it with a utility knife—take care not to cut through the layer beneath—and use a putty knife to force roofing cement under both sides of the slit. Nail down both sides with roofing nails and cover with more cement. Then apply a shingle or tar-paper patch, nail it down, and cover with cement. For a large damaged area, cut away all tattered or worn material and apply roofing cement to the bare area, overlapping 2 inches all around. Then patch as above.
If a flat roof curls at the edges, brush debris out from under the curl and force roofing cement under it. Nail it down with roofing nails and apply more cement over the nail heads and at the edge.