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Roof Leaks

Because it covers and protects all other components from the elements, the roof may be the most important part of house. Inspect the roof for signs of age and damage each spring before wind- storms and rains begin, and again each fall before winter’s onslaught. Also check the home interior—the attic, ceilings, and walls—for any sign of water entry or damage. With periodic inspection you can catch roof leaks quickly, minimizing the extent of the damage and repair costs.

Roof Waterproofing: Any flashed area poses a potential roof leak.


Because the majority of roofs in North America are covered with asphalt shingles, I’ve directed my advice to those readers with asphalt shingles.

If you can determine the age and construction of the shingles, you will be able to determine how much longer they will last. Until 20 years ago, asphalt shingles had a felt or tar paper base and an asphalt coating. To help protect the shingles from solar damage, the asphalt coating was covered with gravel. The warranty for these older shingles varies widely: the thicker and heavier the shingles, the longer the warranty. Depending on the quality and weight of the shingles the old-style shingle carried a warranty of between 15 and 20 years.

However, the life of shingles also depends on other son, it may be difficult to locate and patch a leak in the roof.

If you have a stain or a wet spot on a ceiling, use a flashlight with a bright beam to check the attic. First, pull back any ceiling insulation over the wet spot and inspect the water dam age. If the area is simply damp, leave the insulation pulled back from the wet spot so air can reach and dry it. When the ceiling and insulation are completely dry, replace the insulation between the rafters.

Standing water on a ceiling surface will result in serious and extensive dam age to the wallboard or plaster, so you should act quickly to remove the standing water. If there is standing water on the attic side of the ceiling, place a pail under the spot to catch the water, then bore a hole through the wallboard or plaster ceiling to let the water drain through and escape. Ceilings that are wetted only for a short period will usually be easy to repair.

Because water is present and there is danger of a shock from using an electric drill, use a hand drill or a cordless battery-powered drill to make the drain hole through the ceiling. A drill bit that's ¼ inch (0.5 centimeter) in diameter will usually make a hole large enough to allow the water to drain through. When all standing water has drained, leave the insulation pulled away from the area until the ceiling and insulation are dry. You can speed the drying process by placing a small fan, directed at the repair area, in the attic. If the leak is near an electric ceiling fixture, turn off the circuit and have an electrician clean and dry the fixture.

When the area is dry, patch the hole you have drilled in the ceiling by using a taping knife to spread premixed taping com pound over the repair area. Then embed a piece of fiber wallboard tape over the hole. Use the knife to smooth the patch and to remove excess taping compound. When the tape is dry, apply a second coat of compound over the patch, smoothing the edges of the patch with the knife. Apply a third coat if necessary to conceal the tape.

Then sand lightly, apply a coat of sealer over the patch area, and repaint.

To find the leak, use your flashlight and inspect the underside of the roof sheathing and the rafters near the leak for stains or wetness. Do this during or immediately after a rain. Often you can see and trace the rain’s entry path. While in the attic, calculate the location so that you can find the exact location from the exterior of the roof. E.g., if the water entry is near a furnace stack, roof vent, valley, or fireplace chimney, you can climb onto the roof and use the chimney or stack as a reference point to find the leak area and make a permanent repair.

If you can't locate the leak from inside the attic, inspect the roof care fully. The most common points for roof water entry are along valleys, or at chimney or furnace stack flashings. Check around the flashing to find the point of water entry. Inspect the flashing for any holes or rusted areas, and use a fiber glass repair kit to patch them. Often, liberal application of roof mastic along the top and sides of the flashing will stop the leak. If these steps are unsuccessful in patching the leak, or there are signs of extensive problems, call in a professional roofer.

Finding the Leak: Look for water stains on the roof sheathing to find a leak.

Bore a Drain hole in the Ceiling: Use an awl or a cordless drill to bore a drain hole in the ceiling to let water run out.


Roof Leak: Place a pail in the attic to catch water from leak.

In cold winter climates, roof ice dams can cause roof leaks. Although most ice dam problems occur in the north, ice dams may be a problem as far south as Texas.

If you get a snow buildup on your roof, and the weather warms up, the sun will quickly remove the snow by melting it from the top down, and no ice dam will form. The conditions that produce roof ice dams develop when both snowfall and an extended period of cold weather occur. Then the snow lingers on the roof. As heat escapes from the house interior, upward through the ceilings, there is a heat buildup in the attic, with the warmest temperatures being at the highest point or ridge of the attic. This warm air will melt the snow on the highest points of the roof. The water will run down the roof, under the remaining snow, to the eaves. At the eave level the attic temperatures are cooler, so the water may freeze there or at the soffits to form a dam that will trap the water. The water will continue to melt at the higher levels of the roof, run down to the ice dam, and form a pool of water. The ice dam causes the water to back up and run under the shingles. Water entry due to ice dams will usually cause a stain or wet area at or near the point where the ceiling meets the outside walls. (See “Ice Dam” illustration below.)

Ice Dam

The most effective way to eliminate ice dams is to correct the ceiling insulation and attic ventilation to eliminate heat buildup in the attic, i.e., establish a cold roof deck. First check the recommended ceiling insulation depths, or R-factor, for your area. Then measure the ceiling insulation depth to be sure your insulation meets current recommendations. If it does not, have additional insulation blown into the ceiling. Be sure that the insulation layer extends past the top wall plates—i.e., the horizontal top 2 x4 or 2 x 6 of the wall—but does not completely block ventilation from the soffit area into the attic. Back insulation away from the soffits just enough to permit air to flow from soffit to attic. Also inspect the attic area for heat leaks—voids or cracks where heat can pass through the ceiling and enter the attic. These heat leaks often occur around ceiling light outlets, where furnace stacks or plumbing vents penetrate the ceiling, or around attic access doors. To seal the heat leak areas, fill even the smallest void or crack with fiberglass insulation. Caution: don't cover the attic side of recessed light fixtures with insulation. The bulbs in the recessed lights generate a lot of heat, and insulation atop the fixture may cause a fire.

When insulation levels are up to code, check the attic ventilation. The best attic ventilation is continuous soffit/ridge vent. This means that vents are uninterrupted from end to end of the house, as opposed to the installation of individual vents at selected points along the soffits and ridge or roof deck. Newer houses usually have continuous soffit/ridge venting, but houses built more than ten years ago may have inadequate attic ventilation. If your attic ventilation is substandard and you are planning on re roofing soon, be sure to have the continuous soffit/ridge vents installed as part of the roofing project. Wait until you re-roof , using existing vents. Roof vents remove hot air and moisture. If you have ice dams, ask a contractor to install more vents—select type from the illustrations.

The theory of having continuous soffit/ridge venting is based on the fact that warm air rises, a phenomenon called the chimney effect. As attic air is warmed, it rises and exits through the ridge vents. As the warm air moves out through the higher ridge vents, cooler air is pulled into the attic through the soffit vents, moves across the insulation to remove any moisture in the attic, is warmed, and rises to exit at the ridge vents. This process does not depend on power fans or ventilators, but is a natural process caused by the hot air rising.

With adequate ceiling and proper ventilation, the temperature in the attic will not vary widely from ridge to soffit levels. Snow will then be melted from the top side by the sun and run off the roof, rather than forming ice dams at the eaves.

Some homeowners cover attic vents in winter, hoping to save on heating costs. But once heat has escaped into the attic, it's no longer heating the house, and should be exhausted to prevent ice dams.

There is currently some argument between experts on the value of attic ventilation in preventing ice dams. Nevertheless, it seems reasonable to assume that, no matter the depth of insulation, some heat will escape into the attic. Unless that heat, and any additional heat generated from the sun, is vented outside, it will melt the snow from the bottom or shingle side, even on cold and sunless days, and ice dams will form at the cold soffits. (Heat rises and melts the snow at the upper roof or ridge; the lower roof to the soffits stays cold so water refreezes at the soffits.) Proper attic ventilation is absolutely essential to eliminate ice dams.

Attic Ventilation

Continuous Soffit Vent: Soffit vent in trim provides ventilation along the length of the soffit.


If you have a roof covered with wood shingles or shakes, you may have problems with mildew or moss growing on the wood surfaces. In order for either to grow, moisture must be present. Often the moisture will be retained on the shingles because of shade trees whose canopies overhang the roof deck. Hire a tree trimmer to thin the crown of the trees, so that sunlight and wind can penetrate to dry the roof deck.

Clean the roof deck often to remove any twigs, leaves, or other debris. This debris not only will retain water but will also block the drainage slots, called keyways, between the shingles. The resulting moisture buildup will sup port the growth of mildew or moss.

If mildew (fungus) or moss (plant) are already present on your roof, ask your home center to recommend a fungicide or herbicide product to kill the growth. If you don't wish to do the treatment yourself, hire a roofer to perform the task.


It is essential to perform a roof inspection while standing on the roof, where you can have a close-up view of the ridge, valleys, flashing, and shingles. If your roof is too high or steep to climb, or you are physically unable to climb, have a professional roofer do the inspection.

Check the appearance and condition of the shingles. Signs of shingle failure include uneven or curling shingle tabs; a ragged edge at the tabs, which indicates wear and weathering; missing or broken shingles; and excessive loss of granules.

As the shingles age and dry out from solar exposure, the surface granules will loosen and be washed by rain down the roof deck. Check in the gutters and at splash blocks under ground pipes for a buildup of granules.

Next, check the ridge row. These are the shingles that cover the ridge or peak of the roof where two ascending slopes rise and meet. Replace or repair missing or damaged ridge shingles.

A valley is the point on the roof where two shingled areas or descending planes meet. Check the shingles near the valleys and the flashing of the valley. On a minority of roofs the shingles will be woven together at the valleys, but metal or fiberglass flashing is the common valley treatment. Any interruption in the roof shingles—valleys, flashing, vents—is a possible source of leaks.

On roofs more than 20 years old, galvanized steel flashing was used. Unfortunately, galvanized flashing eventually, loses its zinc coating, and the steel will rust, depending on the quality of the material. If you discover your flashing has lost its coating, but rust isn't yet evident, paint the flashing with a paint formulated for metal application, such as Galva-Grip or Rustoleum. If the galvanized valleys are already rusting, use sandpaper or a wire brush to remove as much rust as possible, then paint the flashings using one of the recommended paint products.

For the past 20 years prefinished aluminum flashing is more commonly used. Aluminum is the preferred metal because it does not rust and needs no maintenance. Inspect aluminum flashing for storm damage such as dents or holes, and re-flash where necessary.

In addition to valley flashing, metal flashings are used between shingles and siding where the roof changes plane or direction, such as where the roof of a garage or addition does not match the level of the house roof and forms a juncture with the wall siding.

Inspect the flashing around any interruptions in the roof deck, such as flashings used where a furnace stack, plumbing vent, or fire place chimney penetrate the roof. Be sure the flashings are intact and are securely fastened to the roof. If there is a problem with water entry where the high side of the roof meets a fireplace chimney, have a roofer install a metal device, called a cricket, to divert the water around the chimney. (See “Roof Leak.)

If the shingles aren't sealed against the flashing, use roof mastic to caulk the cracks between the shingles and the flashing. The roof mastic may become brittle and crack with age, so make annual or even seasonal inspections of the mastic and renew as necessary.

Continuous Roof Vent: A 1½-inch (3.8 centimeter) gap in the sheathing at the ridge is covered by this metal ridge vent, which provides ventilation for the entire attic.

Gable vents.

Power vent.

Valley Flashing

Roof leaks.


If the roof is more than 15 years old, if it exhibits any of the aging symptoms mentioned above (see Inspecting a Roof) or if there is a problem with roof leaks that don't respond to repair efforts, it may be time to re-roof. Most building codes permit a re roof directly over a roof that has only one layer of shingles; for good building practice, if the roof has two layers of shingles you must have all shingles and flashing removed down to the roof deck or sheathing and start anew.

As already mentioned, the roof may be the most important component of the house, because it covers and protects all other components. Although re-roofing is an expensive project, the damage that can result from water entry can far exceed the cost of a roof, so having a sound roof is good insurance to protect the entire structure.

Although shingles are widely available from home centers, shingle manufacturers once ignored the D-I-Y business. Roofing is hard and heavy work; it's performed at dangerous heights; it requires use of scaffold that must be rented; and a high skill level is necessary to achieve a weather-tight roof. E.g., few homeowners could successfully flash the point where a garage-level roof meets the house siding, or where the shingles meet a masonry chimney, or install a cricket to divert water around a chimney. You also must dispose of the old roof material. For all these reasons, it's best to have a new roof installed by professionals.

To find a professional roofer, contact the local office of the National Association of Home Builders (NAHB), or the National Association for the Remodeling Industry (NARI). In Canada, check your local Association of Home Builders, or check on the Internet. These are associations that were formed by contractors to provide honest and professional service to the public. They each have codes of conduct and are self-policing.

Choose the materials wisely. Remember that the labor costs are equal regard less of the quality of the shingles. If you select a quality shingle with an extended warranty of 35 years, you can ensure that you won’t need another roof for a long time.

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