Roof Leak Overview
If you have a roof leak, you'd better fix it immediately, even if it doesn't bother you much or you're getting a new roof next year. Even over a short time, small leaks can lead to big problems, such as mold, rotted framing and sheathing, destroyed insulation and damaged ceilings. The flashing leak that caused an expensive repair bill was obvious from the ceiling stains for over two years. If the homeowner had dealt with it right away, the damage and subsequent repairs would have been minimal.
How to Find Roof Leaks
If you have attic access, the easiest way to track down a leak is to go up there with a flashlight and look for the evidence. There will be water stains, black marks or mold. But if access is a problem or you have a vaulted ceiling, you'll have to go up onto the roof and examine the suspect(s).
A Trick for Finding Difficult Leaks
Solution for a Small Leak
If you can't see any telltale flow marks, and since the stain is fairly small, look at the underside of the roof for 'shiners.' A shiner is a nail that missed the framing member, in this case when the carpenter nailed the roof sheathing to the rafters. Moisture that escapes into the cold attic from the rooms below often condenses on cold nails. Sometimes you can spot this if you climb up into your attic on a cold night. The nails will look white because they're frosted. When the attic heats up a bit during the day, the frost melts and drips, then the nails frost up at night again and so on. The solution is to simply clip the nail with a side-cutting pliers.
Fix Plumbing Vent Boots
Fix Roof Vents
Fix Walls and Dormers
Complex Roof Problem
The solution begins with good flashing, since this should stop leaks from rainfall and might stop the leaks from ice dams as well. Begin by removing the shingles down to the wood sheathing and slip a strip of adhesive ice-and-water barrier (available where roofing products are sold) under the soffit/main roof joint. Depending on how the roofs join, you may have to cut a slot to work it in far enough. It should overlap another piece of ice-and-water barrier laid below, all the way down to the roof edge. This should cover the most leak-prone areas. Then reshingle, sliding metal step flashing behind the fascia board (the trim behind the gutter). The valley flashing, laid over the joint where the two roofs meet, should overlap the step flashing at least 2 in.
If leaks continue to occur from ice dams, consider installing roof edge heating cables. (Find them locally at hardware stores or home centers.) Improved attic insulation and ventilation are usually the best ways to prevent ice dams, but they might not be effective in this complicated roof situation.
Fix Step Flashing
Don't Count on Caulk!
Fix Small Holes