How to find and fix flashing leaks

If you see signs of a leaky roof, check the flashings – those strips of metal that seal the seams around chimneys, vent pipes, dormers, and valleys (low points between roof sections). You may see breaks or pinholes from inside on a sunny day; or you may find discoloration in the flashings, on the roof around them, or on the ceiling or wall beneath.

If the leak is small, fill it with plastic asphalt roof cement, smoothing it carefully with a trowel to eliminate rough spots where water might collect. For a hole of 1 square inch or more, cut a patch from the same material as the existing flashing and 1 inch bigger all around. Coat the area around the hole with cement and set the patch over it. Then coat and smooth the patch and the seam. If you cannot find the leak, apply plastic cement in all logical areas.

The cap flashing around chimneys may separate from the mortar in which it is imbedded. If this happens, chip away the mortar, clean the channel to the depth of about 3/4 inch, and reposition the flashing. Fill with fresh mortar or caulking.