How To: Find a Roof Leak

Leaky roof? Try these strategies for pinpointing the problem, in fair weather or foul.

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How to Find a Roof Leak

Photo: shutterstock.com

The hardest part of fixing a roof leak? A lot of times, it’s simply locating the problem. Sure, it’s easy enough to spot water stains or mold growth—sure signs of a leak. But once water has penetrated the roof, it’s easily diverted by such things as insulation. So even though you may notice the evidence of a leak in the corner bedroom, the vulnerable point in your roof may be quite far removed from that part of your house. That’s why roof repair jobs typically begin with a certain amount of detective work. Here are some tips to help you crack the case quickly, so you can plug the leak before the damage gets any worse.

Get a Good Look
Arm yourself with a flashlight and head up to the attic. Be careful up there: If there’s no proper flooring, step carefully from joist to joist. (If you step between the joists, you might put a foot through the ceiling of the room below!) Once you’ve got your bearings, use the flashlight to examine the underside of the roof. Look out for any areas that are darker than the surrounding roof sheathing. If there hasn’t been rain recently, moist spots may be too difficult to discern. Mold, on the other hand, has the tendency to linger. So if you encounter a patch of mold, which thrives on moisture, chances are you’ve found the vulnerable point in your roof.

Interfering Insulation
The underside of your roof may be obscured by insulation, and that’s helpful for the task at hand, because insulation deteriorates more noticeably and more quickly than wood does. If you’re seeing damage on one section of the insulation, however, you must remember that the leak itself may be several feet to either side. It’s best to carefully remove all insulation adjacent to the spot where you notice signs of a leak. That way, you can follow the path of the water from the damaged area all the way to the water’s entry point in the roof. Remember that whenever you are working with insulation, it’s important to wear the appropriate protective gear.

Foreign Objects
Most noticeable to the eye are leaks caused by an object (for example, an errant nail) that’s managed to pierce the roof. Failing any such obvious signs, check out the roof vents. If present, these vents are typically near ridges or gable ends, or both. Over time, the seals around vents can gradually weaken, allowing rainwater to seep in.

Dry Weather
What happens if you’re desperate to find a roof leak, but recent dry weather has made your search more challenging? Well, you can always simulate a storm. This method requires two people. While one person goes up on the roof, garden hose in tow, the other person remains in the attic, flashlight in hand. Section by section, the person on the roof wets down the roof, while the other carefully examines the roof’s underside for leakage. By simulating a downpour, you can witness firsthand how your roof withstands—or fails to withstand, as the case may be—conditions that mimic those of a natural storm.

The Next Step
Leaks only get worse. Act quickly once you’ve pinpointed the location of yours. Fortunately, in many instances it takes only a modest repair to fix the leak—for example, replacing a shingle. If you don’t feel comfortable on the roof, however, or if the leak seems extensive, do not hesitate to contact a professional.