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Roof Repair: How to Find and Fix Roof Leaks

We show you how to track down and fix the most common types of roof leaks. Most leaks take only minutes to repair.

By the DIY experts of The Family Handyman Magazine

Overview: The roof leak problem

If you have water stains that extend across ceilings or run down walls, the cause is probably a roof leak. Tracking down the leak is the hard part; the fixes are usually pretty easy. We’ll show you some simple tricks for finding and repairing most of the common types of roof leaks. But if you live in the Snow Belt and in the winter you have leaks only on warm or sunny days, you probably have ice dams. We won’t go into those fixes in this story.

Minor leaks can cause major damage
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 (Photo) 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

When you’re trying to track down a leak, start by looking at the roof uphill from the stains. The first thing to look for is any roof penetrations. Items that penetrate the roof are by far the most common source of leaks. In fact, it’s rare for leaks to develop in open areas of uninterrupted shingles, even on older roofs. Penetrations can include plumbing and roof vents, chimneys, dormers or anything else that projects through the roof. They can be several feet above the leak or to the right or left of it.

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).

If the problem still isn’t obvious, enlist a helper and go up on the roof with a garden hose. Start low, soaking the area just above where the leak appears in the house. Isolate areas when you run the hose. For example, soak the downhill side of a chimney first, then each side, then the top on both sides. Have your helper stay inside the house waiting for the drip to appear. Let the hose run for several minutes in one area before moving it up the roof a little farther. Tell your helper to yell when a drip becomes visible. You’ll be in the neighborhood of the leak. This process can take well over an hour, so be patient and don’t move the hose too soon. Buy your helper dinner.

Frosty shank of a nail that protrudes several
inches through the roof sheathing

Solution for a Small Leak

Some roof leaks are tough to locate. Sometimes the water shows up at a ceiling spot distant from the leak. If your ceiling has a plastic vapor barrier between the drywall and the attic insulation, push the insulation aside and look for flow stains on the plastic. Often water runs to openings in the vapor barrier, such as at ceiling light fixtures.

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 common leaks: Plumbing vent boots

Plumbing vent boots can be all plastic, plastic and metal, or even two-piece metal units. Check plastic bases for cracks and metal bases for broken seams. Then examine the rubber boot surrounding the pipe. That can be rotted away or torn, allowing water to work its way into the house along the pipe. With any of these problems, you should buy a new vent boot to replace the old one. But if the nails at the base are missing or pulled free and the boot is in good shape, replace them with the rubber-washered screws used for metal roofing systems. You’ll find them at any home center with the rest of the screws. You’ll have to work neighboring shingles free on both sides. If you don’t have extra shingles, be careful when you remove shingles so they can be reused. Use a flat bar to separate the sealant between the layers. Then you’ll be able to drive the flat bar under the nail heads to pop out the nails.

Fix common leaks: Roof vents

Check for cracked housings on plastic roof vents and broken seams on metal ones. You might be tempted to throw caulk at the problem, but that solution won’t last long. There’s really no fix other than replacing the damaged vents. Also look for pulled or missing nails at the base’s bottom edge. Replace them with rubber-washered screws. In most cases, you can remove nails under the shingles on both sides of the vent to pull it free. There will be nails across the top of the vent too. Usually you can also work those loose without removing shingles. Screw the bottom in place with rubber-washered screws. Squeeze out a bead of caulk beneath the shingles on both sides of the vent to hold the shingles down and to add a water barrier. That’s much easier than renailing the shingles.

Fix common leaks: Walls and dormers

Water doesn’t always come in at the shingled surface. Often, wind-driven rain comes in from above the roof, especially around windows, between corner boards and siding, and through cracks and knotholes in siding. Dormer walls provide lots of spots where water can dribble down and enter the roof. Caulk can be old, cracked or even missing between the corner boards and between window edges and siding. Water penetrates these cracks and works its way behind the flashing and into the house. Even caulk that looks intact may not be sealing against the adjoining surfaces. Dig around with a putty knife to see if the area is sealed. Dig out any suspect caulk and replace it with a siliconized latex caulk. Also check the siding above the step flashing. Replace any cracked, rotted or missing siding, making sure the new piece overlaps the step flashing by at least 2 in. If you still have a leak, pull the corner boards free and check the overlapping flashing at the corner. Often, there’s old, hardened caulk where the two pieces overlap at the inside corner.

Soffit of one roof meeting another roof

Soffit of one roof meeting another roof

Complex Roof Problem

This roof leaks during the snowy part of winter and during storms in the summer, certainly due to poor flashing. The soffit that meets the roof is one of the toughest areas to waterproof. In the photo, you can still see signs of an ice dam. An ice dam occurs when snow melts and the water freezes when it hits the colder edges of your roof. Eventually, water pools behind the dam and works its way back up under the shingles and under the soffit until it finds an opening through the roof.

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 common leaks: Step flashing

Step flashing is used along walls that intersect the roof. Each short section of flashing channels water over the shingle downhill from it. But if the flashing rusts through, or a piece comes loose, water will run right behind it, and into the house it goes. Rusted flashing needs to be replaced. That means removing shingles, prying siding loose, and then removing and replacing the step flashing. It’s that simple. But occasionally a roofer forgets to nail one in place and it eventually slips down to expose the wall.

Don't Count on Caulk!

Rarely will caulk or roof cement cure a roof leak—at least for very long. You should always attempt a "mechanical" fix whenever possible. That means replacing or repairing existing flashing instead of using any type of sealant. Only use caulk for very small holes and when flashing isn't an option.

Fix common leaks: Small holes

Tiny holes in shingles are sneaky because they can cause rot and other damage for years before you notice the obvious signs of a leak. You might find holes left over from satellite dish or antenna mounting brackets or just about anything. And exposed, misplaced roofing nails should be pulled and the holes patched. Small holes are simple to fix, but the fix isn't to inject caulk in the hole. You'll fix this one with flashing.

Chimney flashing is complicated

Chimney flashing is complicated

Leaks Around Brick Chimneys

All kinds of bad things can happen around brick chimneys. In fact, there are far too many to cover in this story. Flashing around chimneys can rust through if it’s galvanized steel, especially at the 90-degree bend at the bottom. A quick but fairly long-term fix is to simply slip new flashing under the old rusted stuff. That way any water that seeps through will be diverted. The best fix, though, is to cut a saw kerf into the mortar and install new flashing. Get complete instructions on how to install chimney flashing.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

    • Hammer
    • Caulk gun
    • Drill/driver, cordless
    • Flashlight
    • Pry bar
    • Putty knife
    • Tin snips

Garden hose

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

    • Metal flashing
    • Roof caulk
    • Siding caulk
    • Roofing nails
    • Rubber-washer screws
    • Roof vents
    • Plumbing boots

Comments from DIY Community Members

Share what's on your mind and see what other DIYers are thinking about.

1 - 6 of 6 comments
Show per page: 20   All
Shu

March 01, 5:21 PM [GMT -5]

Sounds straight forward enough. I got a leak that's been a mystery. Can see exactly where it's leaking into the attic - looks like around a nail coming through, and from there it's dripping down an angled rafter.Have patched 20 square feet just above it - still leaks. Another I spent a whole day patching every inch of the roof, even laid down tarps to cover the whole roof - still leaked. Laid another layer of tarp to cover the whole roof again - still leaks.

June 13, 1:05 PM [GMT -5]

These are all great ideas but I think an important (first) step would be to call your home owners insurance.

April 21, 11:37 PM [GMT -5]

Thank you so much for your Help.

September 06, 6:24 AM [GMT -5]

For finding leaks just make an inspection of your living place or where you want to find damages. For fixing the roof leaks use a mixture of cement, sand and water. The previous one is a great article and keep sharing.

jacksonville emergency roof damage repair - http://www.emergencycleaningservicejacksonville.com/




Suz

June 03, 11:13 PM [GMT -5]

This was a great article but it didn't make any reference to skylight repairs?? My roof has been leaking for about 6yrs. or longer. Not only am I tired of the XL cat litter pan(to catch the water but I'm concerned about the Mold/Mildew issue. My limited knowledge of leaks, tells me that it very well may NOT be the skylights. I've been in the attic 5 times(0ver the yrs.) and I couldn't see where its leaking. I'm 64 & on Social Sec.and I've been "taken" by more Contractors, than I'd like to admit. So, I try to fix things myself. I did save the article on "Making a Skylight Leakproof" but that's starting from new. Thanks for listening to me, Susan Williams

December 21, 6:07 PM [GMT -5]

Good, thorough treatment of a common problem

Only thing I would add is to forbid the use of SILICONE caulk as a repair material. Many people think silicone somehow is better than "regular" caulk.. In fact, it may last almost forever, but it usually fails to stick for longer than a year in adverse conditions,thus it conceals future problems without fixing anything

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