Nail holes are not unusual in an asphalt roof, but they can also cause leaks. Over time the area surrounding a nail can expand, allowing water to filter down and through the roof. Sometimes you may find that the nail is missing altogether, leaving a small hole in your roof that will leak every time it rains. Luckily, nail holes, once located, are easily repaired.
Step 1: Locate the nail holes that are causing the problem. This can be a difficult task, because leaks in the ceiling do not necessarily mirror the location of the leak in the actual roof. If possible, look when the water is coming in, and try to follow the stream to its origin. Mark each possible spot with tape for easy reference later on.
Step 2: While your asphalt roof is no longer leaking, examine the attic for any nail holes that might possibly leak. On a sunny day, you may actually see glimpses of light through your roof. Mark any possible locations for leaks with tape.
Step 3: Apply a generous dab of roofing cement over the location of any nail holes on the underside of your roof, in the interior of your home. You can use roofing cement that comes in a tube and is used in conjunction with a caulk gun, or a tub of roofing cement that is applied by using a putty knife. If your attic is finished and you can’t gain access to the roofing nail holes without significant damage to the interior finishes, skip this step.
Step 4: Draw a diagram that marks the location of each repaired nail hole, or any nail holes you could not repair due to their location. Include dimensions that will aid you in locating each nail hole.
Step 5: Get on your roof with the roofing cement. Aided by the diagram, locate all of the roofing nail holes. Patch the holes with the roofing cement.
Step 6: Locate asphalt roofing tiles that are not perfectly flat, or were supposed to be covering a nail hole. Use roofing cement to glue these asphalt shingles down: sometimes wind will cause this shingles to shift, causing a leak.