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Where to Look for Leaks in Your Roof

A funny spot on the ceiling of an upstairs room. A water stain running down the wall. Roofing shingles on the ground outside after a windstorm. Rusted flashing.


All are warning signs that your roof might have a leak. In just a short period, small roof leaks can lead to much bigger problems—and headaches—that lead to expensive repair bills to fix mold, rotted framing or sheathing, damaged insulation, and wrecked ceilings. The conclusion to this cautionary tale: When you find something suspicious, don’t put off repairs.


Finding roof leaks

Leaks tend not to occur in open areas of uninterrupted shingles—even on the older roofs. When you’re tracking down a leak, look for roof penetrations. Plumbing and roof vents, chimneys, dormers, and anything else that comes up through the roof are great places to start. Head up to your attic with a good, strong flashlight and look for water stains, black marks, or mold. Can’t access the attic? You’ll need to climb up onto the roof to conduct your investigation.


Sometimes, leaks are tricky to find. If you suspect a leak but can’t locate it, get someone to help. Grab a hose and climb up onto the roof or, if the leak is lower, aim a steady stream of water above where you’ve identified the leak inside your house. Station your second set of eyes inside waiting for water drips to appear. Move slowly up the roof a little further and repeat the process. Ask your assistant to yell when water becomes visible inside. When you receive the signal, remove shingles from that suspected area and look for discolored felt paper or water-stained or rotted wood.


Water can also appear quite a distance from the actual leak. Water often runs to openings in a vapor barrier, like ceiling light fixtures or skylights. If your attic ceiling has a plastic vapor barrier, push the insulation aside and look for water tracks on the plastic.


Common causes of roof leaks


Plumbing and other roof vent boot leaks

If your roof is leaking from the plumbing vent boots, which come in plastic, plastic, and metal, and two-piece metal units, check the bases for cracks and broken seams. Closely examine the rubber boot that surrounds the pipe which can rot away or tear, giving easy access for water to drip into your house along the pipe. For more specific information on how to troubleshoot possible leaks, check out this article.


If you discover water coming in around your roof vent, the best solution is to replace the vent, replace missing nails with rubber-washed screws, and then caulk it. Just caulking the seam of the damaged vent won’t fix the problem for the long haul.


Dormer wall leaks

The wind drives rain and snow in around windows, between corner boards and siding, and through siding’s cracks and holes. Dormer walls provide quite a lot of area for water to sneak through, especially when caulking is old, cracked, or missing between corner boards or between the window edges and siding. For a more in-depth guide to safely checking for dormer leaks, visit the home guides page.


Ice dam leaks

If your area gets any kind of snow in winter, you might find your roof the victim of an ice dam. Ice dams occur when the snow melts but the melted water freezes where it hits your roof’s colder edges. Water can pool behind the dam, working its way gradually up under the shingles and soffit (notoriously hard to waterproof) until it finds a place to seep through an opening in the roof. This step-by-step guide will help you to diagnose and repair the damage caused by ice dam leaks.


Step flashing leaks

Roofers use step flashing along walls that intersect the roof to channel water over the shingle downhill to the gutters. Unfortunately, flashing can rust—and when that happens, or a piece loosens, the water runs behind it and right into the house. A visual inspection may not be enough to identify the problem if the rust isn’t immediately visible or you can’t find a safe position to verify that the flashing is still securely nailed to the roof. This video shows the water hose testing technique.


Antennae hole leaks

If you’ve ever had an antenna or cable satellite on your roof removed, the mounting brackets can leave small holes behind. These holes are pretty darn sneaky because they aren’t easily noticed and can cause rot and damage for years before you ever realize you’ve got a leak. So double-check those areas as soon as you’ve had any type of equipment removed to ensure that the holes have been properly plugged.


Brick chimney leaks

These important structures do, nevertheless, come with a host of problems that include flashing around the bottoms which can rust, if it’s made of galvanized steel; water can infiltrate the masonry structure and cement cap. Condensation can occur and “masquerade” as a leak, too.


Water, water everywhere

Whether it’s a water stain on the ceiling or discolored ceilings or walls, it’s worth investigating. When drips appear only occasionally—and disappear for a time—check it out anyway. Chronic moister problems can cause major (and expensive) damage.


Have water spots along your roofline? That’s a flashing issue and worth hiring someone to fix—or fixing yourself. When your external walls begin to grow moss or mold, and that’s not the part of your home that lives in the shade, you might have a downspout or gutter issue. Investigate further.


Roofs that lose shingles in storms or during the rainy/snowy seasons are prone to leaking over time, so if you see a few spots looking a little “shingle-bare,” hire a contractor to inspect your roof and proactively address smaller issues before they grow into larger problems.


Roofs need love

A healthy roof is important to your home’s overall well-being. It protects the interior of your home—and your expensive investment—from the rest of the world. A good, structurally sound roof increases your home’s energy efficiency and saves money on heating and cooling. If you need to replace a badly damaged or old roof, know that a new roof also is a good selling point. According to Remodeling Magazine’s 2017 report, a new roof can increase your home’s value by $14,000 or more.

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