How to Repair Shingled Roofing

Welcome to the How To clinic on repairing shingled roofing. This clinic will focus more on the repair side of things, rather than a complete installation. Maintenance will also be emphasized and since roofing can be a major expense, finding the problems while they are small keeps your expenses from going through the roof.

Some Roofing Terms

Algae discoloration. A type of roof discoloration caused by algae. Commonly called fungus growth.

Asphalt. A bituminous waterproofing agent applied to roofing materials during manufacture.

Asphalt plastic roofing cement. An asphalt based cement used to bond roofing materials. Also known as flashing cement or mastic.

Blisters. Bubbles that may appear on the surface of asphalt roofing after installation.

Brands. Airborne burning embers released from a fire.

Bundle. A package of shingles. There are 3, 4 or 5 bundles per square.

Butt edge. The lower edge of the shingle tabs.

Caulk. To fill a joint with mastic or asphalt cement to prevent leaks.

Cement. See asphalt plastic roofing cement.

Class "A." The highest fire-resistance rating for roofing as per the American Society for Testing and Materials (ASTM). Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.

Class "B." Fire-resistance rating that indicates roofing materials is able to withstand moderate exposure to fire originating from sources outside the building.

Class "C." Fire-resistance rating that indicates roofing material is able to withstand light exposure to fire originating from sources outside the building.

Counter flashing. That portion of the flashing attached to a vertical surface to prevent water from migrating behind the base flashing.

Course. A row of shingles or roll roofing running the length of the roof.

Deck. The surface, installed over the supporting framing members, to which the roofing is applied.

Downspout (leader). A pipe for draining water from roof gutters.

Drip edge. A non-corrosive, non-staining material used along the eaves and rakes to allow water run-off to drip clear of underlying construction.

Eaves. The horizontal, lower edge of a sloped roof.

Eaves flashing. Additional layer of roofing material applied at the eaves to help prevent damage from water back-up.

Felt. Fibrous material saturated with asphalt and used as an underlayment of sheathing paper.

Flashing. Pieces of metal or roll roofing used to prevent seepage of water into a building around any intersection or projection in a roof such as vent pipes, chimneys, adjoining walls, dormers and valleys. Galvanized metal flashing should be minimum 26-gauge.

Gutter. The trough that channels water from the eaves to the downspouts.

Lap. To cover the surface of one shingle or roll with another.

Masonry primer. An asphalt-based primer used to prepare masonry surfaces for bonding with other asphalt products.

Mastic. See asphalt plastic roofing cement.

Open valley. Method of valley construction in which shingles on both sides of the valley are trimmed along a chalk line snapped on each side of the valley. Shingles do not extend across the valley. The flashing is exposed.

Overhang. That portion of the roof structure that extends beyond the exterior walls of a building.

Pitch. The degree of roof incline expressed as the ratio of the rise, in feet, to the span, in feet.

Ply. The number of layers of roofing: i.e. one-ply, two-ply.

Ridge. The uppermost, horizontal external angle formed by the intersection of two sloping roof planes.

Ridge shingles. Shingles used to cover the horizontal external angle formed by the intersection of two sloping roof planes.

Rise. The vertical distance from the eaves line to the ridge.

Roll roofing. Asphalt roofing products manufactured in roll form.

Rolling tape. An asphalt-saturated tape used with asphalt cements for flashing and patching asphalt roofing.

Run. The horizontal distance from the eaves to a point directly under the ridge. One half the span.

Self-sealing strip or spot. Factory-applied adhesive that bonds shingle courses together when exposed to the heat of the sun after application.

Sheathing. Exterior grade boards used as a roof deck material.

Slope. The degree of roof incline expressed as the ratio of the rise, in inches, to the run, in feet.

Soffit. The finished underside of the eaves.

Soil stack. A vent pipe that penetrates the roof.

Span. The horizontal distance from eaves to eaves.

Square. A unit of roof measure covering 100 square feet.

Tab. The exposed portion of strip shingles defined by cutouts.

Valley. The internal angle formed by the intersection of two sloping roof planes.

Vent. Any outlet for air that protrudes through the roof deck such as a pipe or stack. Any device installed on the roof, gable or soffit for the purpose of ventilating the underside of the roof deck.

Roofing Materials

You may have already been up on the roof checking it out--and did the roof tell you anything while you were there? Here's some general information about roofing types and their characteristics you might be interested in, assuming its not over your head. Later on, we'll discuss how to fix some of their problems.

Composition shingles. Also called asphalt shingles, they are by far the most popular and least expensive, weighing 215 to 300 pounds per square (100 square feet). Durability is determined by the weight and fabric used for the central core. The most durable has a fiberglass core rather than felt. Fiberglass-core shingles have a Class A fire rating whereas felt core is rated Class C. The easiest to apply are 3-tab shingles, which are 12 inches wide and 36 inches long.

Strips of roofing cement come with most roofing shingles to seal the tabs as you apply them. The actual installation process completes with the sun melting the mastic which bonds the shingles together.

Over the years some shingles will begin to curl, crack and lose their surface coatings. High winds can lift older shingles right off.

Wood shingles and shakes. These two are made of wood, usually western red cedar. Shingles are smaller, thinner, and lighter than shakes and are sawn on both sides. Shakes are split by hand. They cost more because of their size and manufacturing process. They also last longer than wood shingles. Both are expensive and you can probably guess they have a poor fire rating unless specially treated.

Shingles and shakes are graded by number (1, 2 and 3) with 1 being the best. Only number 1 should be used for roofs, though, because it comes from heartwood and is free of knots. Originally, number 1 shakes and shingles were made from first-growth timber and lasted for 50 years or more. Today they come from second- and third-growth timber and their life span has been cut in half (20 to 25 years).

Unsealed types tend to rot, warp, and split, weathering to a soft gray color.

Wood-fiber shingles. Much less expensive than wood shingles and shakes, these are made out of compressed hardboard and come in panels 4 feet in length. You install them the same way as their expensive brothers but the job goes a lot quicker because they have alignment marks that make it unnecessary to measure each course.

On Your Way Up: Using Extension Ladders

For strength and rigidity, select a Type I- or Type II-class ladder. It should be long enough to extend three feet above your home's highest eave. Add another additional foot to this for the propping angle. Here are some precautions:

1. Stay away from power lines. Even a wood ladder that's wet can conduct electricity.
2. Allow only ONE person on the ladder at a time.
3. Don't use the ladder on a windy day.
4. Never paint a wooden ladder. This might hide imperfections that could cause future defects.
5. Store your ladder indoors for two reasons: moisture and second-story burglars.

To set up the ladder:

1. Place its feet firmly against the foundation.
2. "Walk" the ladder up, hand over hand, keeping your arms fairly straight. The higher the ladder goes, the lighter it seems to get.
3. To extend the ladder, brace your foot on the bottom rail, lift the ladder off the house, then pull the rope. Make sure both locks catch.
4. The best final position for the ladder is one-fourth the extended length away from the house.
5. Make sure it is resting firmly on the ground. Don't try to shim with bricks or pieces of lumber. If the ladder is uneven, you can purchase a leg leveler for your extension ladder. Never shim it yourself.
6. Use both hands when you climb the ladder.
7. Don't try to carry your tools up with you. Instead, put them in a bucket and hoist them up.
8. Keep your hips between the rails of the ladder and don't overreach, since ladders are fairly easy to move.
9. You may want to use an accessory that improves the ladder's stability, protects siding, spans obstacles, and keeps the ladder away from the house.

Repairing a Shingled Roof

Obviously, if your roof is leaking, you have a problem that requires immediate attention. Some roofing problems are not so obvious, thus it could be years, heck, decades before being detected, resulting in structural damage. So you've got to visit your roof and check it out at least once a year, better yet, once in the spring and once in the fall. Here's what you look for: cracked shingles, rusted flashing, open joints, or brittle mastic. Places to look first are valleys and chimneys. Other places of suspect are ridges, hips, vent flashing and other flashing.

To do this you don't have to climb up on your roof. Invest in a good pair of binoculars and take a good look around, paying particular attention to ridge shingles, valleys, any flashings. A large accumulation of granules in the gutter means your roof is losing its coating. You should expect problems anytime.

Check out your gutters and spouts after a heavy rain to make sure they're free-flowing. If they're not, chances are, water will work its way up under the lower shingles.

When you decide to repair, choose a warm day so the shingles will bend and lift easily. Basically you repair cracked or curled composition shingles, replacing the broken ones. Split or broken wood shingles have to be replaced.

If you're the least bit queasy (chicken) about getting up on your roof, then don't. Hire a professional. If you do decide to tackle it yourself, wait until the sun burns off the dew (it could be slippery) and wear shoes with slip-resistant soles.

You'll need only a few things for your repair job--roofing cement, butyl caulk, galvanized roofing nails, and roofing materials that match your present roof.

The following sections show you how to replace various shingles. If you find a substantial amount of your roof is in disrepair, it might be time to estimate the cost of a new one.

How to Spot the Leaky Spot

If you have access to your attic, you can trace a leak during a rain storm. If you can't wait for a storm, have a (good) friend spray the roof (not you) with a hose while you look for the leak. Mark the rafter where the water is coming through with bright colored chalk, so you can go back and poke a long nail or straightened coat hanger up through the roof. You'll rarely find that the spot on the ceiling is coming from a leak in the roof directly above it.

How to Repair Asphalt Shingles

They're fairly easy to repair. As mentioned earlier, just seal minor cracks or holes and glue down curled shingles with roofing cement. For more extensive damage, you replace the whole shingle strip. Here's how.

1. Work the nails to the shingle above the damaged one loose with a flat shovel.
2. Pull the nails out and remove the bad shingle.
3. Measure your replacement area and cut a new piece to fit.
4. Align the new shingle with the old ones by slipping it into place under the shingle above.
5. Drive new nails through the original holes if you can. If not, seal the old openings with roofing cement.
6. After replacing the nails, coat the nailheads with roofing cement, then press the shingle overlaying it down firmly. Weight it down if necessary. You want this guy to stick.

How to Repair Wood Shingles

Wood shingles and shakes aren't notably sensitive to temperature (unlike Uncle Jake), just humidity. To make them more pliable, soak them good (not unlike Uncle Jake); dry shingles have a tendency to split when you drive nails through them.

Splits. Mend splits by drilling pilot holes on either side of the split. Nail it down. Seal the gap or crack with roofing cement. You might use the kind that can be applied like caulk.

Holes. If the shingle has a hole, drive a sheet of aluminum underneath the damaged shingle, making sure it extends beyond the actual leak.

Decay. Remove a decayed shingle by splitting it along the grain. Cut out the nails that were holding it in place with a hacksaw blade. Drive a new shingle into place using a wood block to protect the shingle from the force of the hammer. Leave about a 1/4-inch space on either side to allow for swelling. Drive a couple of rust-resistant nails just below the lap line to hold the new shingle in place. Seal with roofing cement.

Repairing and Replacing Flashing

Think of flashing as special-purpose shingles. Like shingles, they lap one another, helping to shed water the same way a bird's feathers do. Placed at intersections of the roof line, this makes flashing more vulnerable to leaking, deserving a closer inspection than the rest of your roof.

Look for pieces that have pulled away. Existing roofing cement or caulk that has dried out needs to be replaced. If in doubt, apply new stuff anyway, because leaks can be seemingly microscopic. If the deterioration is widespread, call a roofer or sheet-metal specialist.

Flashing materials include copper, aluminum, galvanized steel, roll roofing, and even plastic and rubber. Aluminum is a reasonably priced, durable choice.

Check over windows and doors periodically for any damage to the drip-cap flashings. These flashings keep water from seeping under the frames.

If the vent flashing is in disrepair, replace it rather than trying to fix it. You just need to remove a few shingles.

Open-valley flashing (you can see it in the V's where the roof lines meet) is easy to inspect. Cement down any shingle that's even thinking about curling. Closed-valley flashings are hidden underneath the roofing and are impossible to check.

Flashing a Chimney

1. Begin by removing all shingles that overlap the roof flashing at the chimney. If you're careful, most of them can be reused.
2. Chip the counter flashing (on the sides of the chimney at the bottom) loose and save it as a pattern to go by. It's usually mortared into the joints of brick chimneys.
3. Remove the roof flashing with a spade. Again, if you're careful, they can be reused.
4. Start installing the bottom roof flashing first, working your way up. Always lap higher courses over lower ones.
5. Cement and nail in place.
6. The counter flashing goes on next. Cut it using the old counter flashing as a guide and bend the tabs to fit into the brick joints, then pack with mortar. The counter flashing should fit 1 1/2 inches into the brick joint.
7. Secure the shingles to the roof flashing with roofing cement.
8. As an extra precaution, weight down the shingles to achieve a snug, tight fit.