Austin Roof Repair Facts: Finding and Stopping Roof Leaks

by Duane Johnson
Rain pounding on the roof may be a comforting sound, but a steady drip somewhere in the attic, living room or bedroom is not. Leaks are more than irritations. They quickly cause costly damage. Paint will bubble and peel, drywall and plaster will fall apart, and a light fixture will fill with water (not as unusual as you might think!). And if you neglect the leak, more serious damage will occur beneath the surface. Persistent dampness causes framing wood to deteriorate, wood to rot and ceilings to sag.

In this article, we’ll tell you how to find those leaks and stop them before they cause big repair bills. Short-term solutions are often inexpensive and easy enough for you to do yourself. However, long-term repairs are usually complex, time-consuming, and you should consider letting the pros do them.

The next time your house needs to be reroofed, keep in mind that most roof leaks are due to second-rate roofing practices. A common mistake is to go the cheaper route of replacing the shingles, but not the flashing, the sheet metal that’s molded around chimneys, dormers and other structures and pipes that penetrate the roof. Having it done right is the best way to avoid leaks in the long run.

Most modern attics are made for insulation, not for walking tours of the underside of your roof. If your attic has insulation covering the floor framing (or if it’s too low to squeeze into), use a powerful flashlight to check the underside of the roof as much as you can from the access hole. If that isn’t enough, slip 4- to 6-ft. long 2x6s onto the floor framing as a catwalk, so you don’t accidentally step through the ceiling. Wear a long- sleeved shirt and pants and a dust mask to protect yourself from the insulation.

When you’re up on the roof looking for leaks, beware: Walking on a sloped roof is dangerous. Unless you’re experienced, let a pro find and solve the problem. Follow ladder safety practices too: Tie it off at the top so it won’t fall and anchor the legs at the bottom so they don’t slip out.

Finally, in homes with cathedral ceilings (where the ceiling follows the roof line), you won’t have an attic to help you trace leaks. Still, you can often find the problem from the clues we show on top of the roof.

The Nitty Gritty of Finding Leaks

GO UP into your attic during or immediately after a rainstorm and check the roof directly above the spot where the moisture appears on the ceiling. That’s where the leak usually occurs. Look for dampness or water stains around nearby roof penetrations, like this chimney or plumbing pipes. The chimney is a common trouble spot, due to continuous movement between the masonry and the framing. Water stains on this chimney and the rotted wood nearby show that it leaked in the past. And the damp streaks show that it’s leaking again.

SQUEEZE plastic roof cement into visible cracks as a short-term solution only. The previous owner or roofer tried a heavy dose of roof cement and hoped it would last. It didn’t. Plastic roof- and asphalt-type cement lasts only a few years when exposed to the ultraviolet rays of the sun. The underlying problem is rusted, punctured or torn metal flashing. The only long-term solution is to replace the flashing. (Pros charge from $200 to $500 for the job.) The backside of a chimney is especially leak-prone. Most chimneys have an angled backside called a saddle (or cricket) that helps water drain. If your chimney doesn’t have one, and it’s more than 2 ft. wide, add one. Otherwise leaves and other debris will build up there, retain moisture, and cause the flashing to rust and fail faster.

LOW-SLOPE roofs are especially leak-prone. Flashing them usually calls for special techniques and a pro’s expertise. This rubber roof and flashing around the door were glued together, which is a good system if done with the proper techniques. However, the roofer cut corners by not running the flashing up under the stucco and behind the door trim. It’ll pull loose and leak within a few years. An alternative that doesn’t require stucco replacement is to cover the top edge of the rubber with a sheet metal flap that’s anchored in a groove (called a riglet) that’s cut into the stucco.

STAINS in the insulation will help you spot some leaks. We show fiberglass insulation here. Cellulose insulation (finely ground newspaper) will actually form a depression that’s crusty to the touch. Because this leak occurred close to the edge of the roof and only in the winter, it was most likely caused by ice dams. Bad roofing wasn’t the cause, but rather poor attic ventilation that allowed ice dams to occur in the first place.

YIKES! You might find odd stuff in your attic, like this bathroom exhaust fan duct routed through the roof at the cast iron soil stack. The rot in the wood around the soil stack and the periodic water that dribbled down to the ceiling below probably weren’t caused by a roof leak. More likely it was moisture in the bathroom exhaust condensing on the roof or roof flashing during cold weather and soaking the wood. The fix: Remove the bathroom exhaust and run it to its own special roof vent at least 2 ft. from the plumbing stack. If that doesn’t stop the moisture, you probably have a rusted vent flashing on the roof (Photo 6).

TIP: Condensation from sweating water pipes and air conditioner lines in the attic could also be the source of water rather than a leaking roof. Keep a sharp eye out for these other possible moisture sources.

CHECK the soil stack flashing if the leak continues. This old flashing is missing the cap that keeps water from running down the sides of the stack pipe. Instead, someone tried to seal the flashing collar to the pipe with caulk. Such seals soon break open. Visible rust usually means that the flashing is failing. The rust is even worse under the shingles where the metal remains wet longer. Exposed nails should be covered with silicone caulk. Solution: Install a new stack flashing.

WHEN you climb up to the roof to look for the leak, count the layers of shingles on the roof edge (each layer is a double layer of the same type and color of shingle) and observe the condition of the top layer. This roof has three layers of shingles. The bottom layer is cedar, which was probably the original. If the metal flashing has never been replaced, it’s about 70 years old — well beyond its useful life. Most flashing lasts 30 to 40 years, usually less than the lifetime of two shingle roofs.

While roofs rarely leak directly through the shingles, replacing flashing without damaging the shingles is difficult. Roofers usually help here by leaving a bundle of shingles behind for repairs, because it’s difficult to find an exact color match. However, in this case, the top layer of shingles is slightly curled and brittle, both signs of age. Since this roof will last only a few more years, most pros would recommend a complete tear-off and shingle replacement as well as new flashing. It’s a tougher call when the shingles still have 10 to 15 years of life left in them.

CHECK the roof framing closely where the roof joins walls and under dormers and roof valleys, all areas where the flashing might be bad. The water on this valley rafter appears higher on the roof, then runs down the rafter several feet before dripping down through the insulation and onto the ceiling below.

While most leaks show up directly below the leaky spot in the roof, water can flow a distance before showing up, either on the underside of the framing, like this leak, or on plastic vapor barriers or drywall. If you can’t get into the attic to trace the flow, the leaky spot on the roof can be difficult and frustrating to locate.

VALLEYS made from asphalt roll roofing (or shingles) become brittle in the sunlight. They often crack and leak when someone steps in them. If you have to go up on your roof, don’t step in the valleys. In addition, two factors make this dormer edge a prime leak candidate. 1. The presence of roof cement suggests either a prior leak or that the flashing wasn’t replaced during the last roofing job. Metal flashing should outlast the first roof, but won’t always outlast the second. 2. The stucco looks original, which also suggests that the flashing wasn’t replaced. To replace it properly, you almost always have to break away the lower 3 in. of stucco, install new flashing and then restucco. Patching stucco is a pro job and can be costly, so many homeowners (and roofing pros!) go for the short-term solution of roof cement.

PATCHING old flashing with roof cement is a temporary solution at best. Once the cement cracks, water seeps in and is trapped, often causing the underlying flashing to rust faster. The urethane sealant we’re using here will last longer than roof cement, but it isn’t a long-term solution either. So don’t get lulled into a false sense of security. Cracks will continue to open and cause periodic leaks until you replace the flashing.

Testing a Roof for Hard-to-Find Leaks

When the location of a leak has you stumped, try simulating wind-driven rain with a spray of water from your garden hose. Do this from a well-secured ladder, because your roof gets more slippery when it’s wet.

Begin spraying likely leak spots at the bottom first, taking at least five minutes to work over each area before moving higher. Have a helper in the attic or in a leak-prone room to spot any dripping water. Douse suspicious flashing areas thoroughly, giving the water time to infiltrate. Expect to take a full hour to work all the way to the top.

Other common leak spots:

• Skylights. Leaks are usually caused by inadequate step or corner flashing, especially if they don’t have a curb that raises them several inches above the roof.
• Wood chimney chases. Unprotected wood chimney enclosures on roofs take a beating from sun and rain and frequently begin to rot near the roof, opening leaks around the flashing. This usually isn’t a roofing or flashing problem. Repair the chase and repaint it.

SMALL holes from nails, screws or the eyebolt that held the TV antenna wire can leak enough to cause a stain on the dining room ceiling. (A bird pecked a hole the size of a quarter through the shingles of my roof, which caused a leak that dripped in the middle of my desk!) Track down the hole in the roof just after a rain so you can find the leak. Drive a nail back up through the roof so you can find the exact location when you go up on the roof to repair it.

STAPLE or nail pops also leave holes that can cause leaks. Drive the staple or nail down flush with the shingle below and seal it with silicone.

TO REPAIR small holes, gently pry up the shingle tab with a putty knife or pry bar. Then spread a bead of roofing cement on both sides of a flashing tin, 5 x 7-in. galvanized steel that costs 20¢ each at home centers. Slip the flashing tin under the tab so it’s completely hidden.