10 Roof Goofs and How to Fix Them
Installation mistakes are often to blame for leaky roofs. Roofer Stephen Hazlett shows how to repair these problems–or avoid them altogether.
Synopsis: Surprisingly, it is not damage from wear and tear that causes most roof leaks but mistakes made during installation or reroofing. This article uses photos and drawings to illustrate what those mistakes are and what you can do about them. The advice is helpful whether you are trying to fix a leak or simply installing a new roof that you hope won’t leak.
As a roofer, I’m frequently called to solve the mysteries of leaky roofs. Surprisingly, it is not damage from wear and tear that causes most roof leaks but mistakes made during installation or reroofing. Some of these mistakes are impractical to repair after the fact. Others are repairable even years after the original installation.
When customers call about a leaky roof, they often have a good idea of where the leak is coming from. Regardless, I start my investigation with a few questions. How long has the roof been leaking? Has it leaked in that area before? How old is the roof?
If the leak has been appearing on and off for years, the problem is likely poor design or poor material choices. If the roof is 20 years old, it just may be worn out. If it is new (two to three years old), the problem is most likely faulty installation.
I first ask to see the water damage inside the house. I try to determine if the leak is even coming from the roof. What appears to be a leaky roof is sometimes a problem with siding or windows.
After I look inside the house, I go to the rooftop, where I usually can narrow the potentially leaky area to a 12-ft. radius around the damage inside. I examine the shingles. If they are in good shape, I look for punctures from nail pops or tree limbs, then check exposed fasteners. Poorly installed plumbing vent stacks, cable-wire guides, and satellite-dish mounts are always suspects on a leaky roof.
If I still haven’t found the source of the leak, I look at the step flashing against sidewalls and chimney flashings. I also inspect all valleys. A valley is susceptible to leaks, and it’s one place where I won’t do repairs. If I find problems in a valley, I replace the entire valley.
Poorly Fastened Sheathing
Sloppy deck installation on new roofs and poorly prepared decks on reroof jobs are among the most common problems I investigate. Poorly fastened sheathing curls along the edges, absorbs water, and swells. This movement causes the nails to pop out. Loose nails puncture the shingles and cause leaks. Tracking down the offending nail is often harder than the repair itself. Once I find and remove the loose nail, I replace the damaged shingle. Nail pops are to be expected over time. On an older roof, they are not a big concern. On a new roof, however, nail pops are a sign of a sloppy installation and frequently are followed by more problems.
For more photos and details on roof repairs, click the View PDF button below.