Roof leaks can be very deceiving; they rarely become evident at the source. Typically, water enters through broken shingles or flashing, then flows along roof sheathing or attic rafters until it finds a convenient place to drip down (see inset at right). There are several likely sources.
Broken shingles are a good tip-off. Anything that protrudes through the roof — such as chimneys, vent stacks, dormers, and skylights — is a possible source. Scan your roof (use binoculars) and look for broken shingles or damaged flashing. If there is no obvious problem, head to the attic during daylight hours.
Look for wet spots or, in dry weather, water marks on the wood. Track the evidence of dampness to its source, then look for a small ray of light coming through the ceiling — the offending hole.
To stop a roof leak temporarily, unroll enough 6-mil polyethylene sheeting to cover the leaky area, plus enough extra to extend several feet over the roof ridge. Wrap each end around a 2-by-4 and staple along the fold; sandwich the sheeting with a second 2-by-4. Place this assembly over the ridge, toward the non-leaking side, then spread the sheeting over the leaking section.
Repair a Broken Asphalt Shingle
1. Remove the nails from the broken shingle, taking care not to damage the shingle overlapping the broken one.
2. Nail down a new shingle. Use a utility bar to drive the nails to avoid damaging the overlapping shingle.
3. Apply roofing cement. Dab it over the new nails and under the edges of all the shingles you disturbed.