Roofing systems are designed so the water flows downward from high point to high point until it runs into a gutter or off an edge. Most roof leaks are caused by a flaw in this progression—water pools up in one spot and begins to damage the material beneath. The resulting moisture penetration can gradually impact the integrity of your house, including your electrical wiring, insulation, drywall, and wooden supports. The key to a complete repair is properly identifying where the leak is occurring and making sure the patch is comprehensive.
Step 1 - Examine your Roof
The first step is to determine the location of the leak so you can plan your approach. Sometimes it can be difficult to locate the exact spot because the damp circles on the ceiling inside your house may not be in the same location as the water coming in from above. Water can run down rafters or trusses and show up inside the house a good distance away from the actual source of the problem.
Try to get a good look at your roof from the ground or from a nearby perch with binoculars. If you see lifted roof shingles, that’s a good place to begin your investigation.
If nothing is apparent from far away, the next step is to climb up into the attic and look for water damage on the underside of the roof deck. This should give you the best idea as to the location where repair work will be necessary. Look for water running down rafters and follow the trickle back to the source. Often water seeps in around flashing on the roof, such as that next to vents or chimneys. Sometimes though, it simply skirts underneath loosened roofing material.
Once you locate the damage on the roof, mark it with heavy bricks that will stay in place until you return with your supplies.
Step 2 - Plan for Safety
Climbing around in your attic and on your roof are activities fraught with opportunity for injury. Use extreme caution at all times and be aware of your footing.
Never repair your leaking roof when it's raining, especially if there are nearby thunderstorms. Tread carefully on the roof and never walk on an area that shows any sign of rotting. Crawl instead of walking to reach the leaks located on hard-to-reach roof areas.
Inside the attic, step only on rafters and never directly into insulation—that could drop you right through the ceiling. Also watch for wiring, flexible hoses, and other materials that could become damaged. You don’t want to cause more problems than you're trying to solve.
On the roof, use a stable ladder that offers access at the correct height without having to climb additional distances. Make sure you have a partner to hold the ladder and bring you supplies as needed. Wear shoes with a good grip and shift your weight into the roof so you don’t lose your balance. Keep your cell phone secured in a zip pocket, or leave it inside.
Step 3 - Apply Roof Patch
Assuming there's no structural damage and the roof and decking do not need to be replaced, a little bit of tar, some flashing, and a few roofing nails will take care of most small, annoying leaks.
The type of repair you make depends on the type of leak you have, but most will involve the use of roofing tar. You can buy this at any home improvement store, where you may also find a suitable kit with all needed supplies. If you're repairing your leaky roof during the rainy season, make sure to use a roof patch that works on wet surfaces.
If the water is coming in through the flat surface of the deck, there may be some wind damage to a shingle, or one may be split because of a direct blow. Things like branches falling out of a tree can cause these kinds of problems. If you happen to have extra shingles that match the color, the easiest option is to simply replace the damaged shingle.
In many cases, however, homeowners don't have extra shingles just lying around. In this instance, take a small pry bar and carefully remove the three or four roofing nails that hold down the shingle in question. Be careful not to tear the shingle anymore than it already is.
Before you apply the roof patch, clean any debris and dirt from the area using a metal brush. Once it's ready, use a trowel to apply an abundant amount of roof patch on the troubled area. Lift tabs and apply a generous coat of tar underneath tears, then nail the shingle back down to the deck.
Apply a heavy layer of tar directly over the tear and a spot of tar over each nail head. If you were unable to use previous nail holes, make sure you cover these with tar as well. Another thin line of tar on the underside of the shingles that overlap the damaged one prevents ice from backing up under the shingle in the winter. A new shingle has a line of tar on the underside already, but you may have broken this seal when lifting it up to make the repairs, so it's a good idea to apply a little more.
If the leak is coming in from around a chimney or a vent of some kind, then it is likely that the seam where the flashing meets the chimney or vent pipe has developed a gap. This can happen if the caulk that was used begins to dry out, or if the pipe was hit and shifted slightly. In most cases, a fresh coat of tar at this seam will solve the problem.
Proceed with patching up the rest of the troubled areas on your roof identified during your initial inspection. Work methodically to make sure you don't miss a marker.
Step 4 - Other Types of Repairs
Occasionally, the flashing may have been pierced by a falling tree branch or a wayward footstep, and will need to be replaced. You can buy rolls of aluminum flashing at most home improvement stores, and it is flexible enough to be cut and worked by hand and with a pair of simple tin snips. Gently loosen the shingles that cover the old piece of flashing and remove it.
When you tack down the new flashing with roofing nails, be sure to seal around the edges with a generous coat of tar. Lay the shingles back down around the new flashing in the same pattern that they were originally laid and make sure that the flashing is tightly sealed to the pipe or chimney that it protects.