Flashing and Other Roofing Materials

Examine the many different construction materials that you may need to complete your roofing project.
Flashings

In addition to the roofing material, you will need several materials to complete the job. For most projects the list is fairly short: underlayment, flashing, fasteners, and roofing cement. However, you must make decisions regarding the type of materials.

Flashings
Metal flashings have been the most common type for many years. Aluminum, which will never rust, is generally preferred over galvanized steel, which can rust. Copper flashing is beautiful but expensive. Vinyl flashing products are gaining in popularity. They are easy to work with and do not crease easily, as do metal flashings. It is possible to make your own flashings by bending metal strips or rolls, but in nearly every case, you can buy preformed flashings that install easily and do the job well. Black, brown, white, and natural metal are the most common flashing colors.

If you have a valley and want to flash it open-metal style, buy valley flashing made for the purpose. The best type has attaching cleats, so you don't have to drive nails through the flashing itself.

There are two basic types of drip edge. T-shape is stronger and will support roofing that overhangs the eaves. L-shape flashing is also common. You can use L-shape drip edge for the rake and T-shape drip edge for the eaves. Cap drip edge is ideal for sealing multiple layers of roofing.

For step flashing, you can buy prebent pieces or blanks that you bend yourself. For counterflashing on chimneys, use blanks or cut pieces from a roll of flashing.

Self-stick flexible flashing is more commonly used when installing windows and doors, but it can sometimes be used in difficult flashing situations, such as where a roof meets a wall.

You'll also need boot flashing, vent pipe flashing with rubber gaskets that simply slides onto the pipes to provide a watertight seal. You can buy boot flashing with metal or plastic flanges. Concrete tile installations require a lead sleeve-type flashing. You'll probably need to buy that from a specialty building supplies dealer.

Roofing Nails

Buy nails that are long enough to completely poke through the sheathing; the length will depend on how thick the roofing is and how many layers of roofing there are. Galvanized nails are the most common choice for hand-nailing roofing. Use aluminum nails for attaching aluminum flashings, and copper nails for attaching copper flashings; if you mix metals, the nails or the flashing could corrode. Nails with plastic caps are sometimes used to attach underlayment in high wind areas. If you use a power nailer, buy roofing nails in coils. Wide-crown staples are also sometimes used with pneumatic nailers. Nails for cedar shakes or shingles have thin shanks and small heads.

Roofing Cement

Thick roofing cement, which is either troweled on or applied with a caulk gun, is the most common type used in roofing. For an emergency patch you can apply wet-surface cement even while rain is coming down. Liquid lap cement is used for applying sheets of roll roofing.

Roofing Felt

Often called tar paper, roofing felt is a critical component of a roof. Thirty-pound felt is twice as thick as 15-pound felt, making it more durable and less likely to wrinkle when you install it. Traditional felt is infused with asphalt; newer types are fiberglass-reinforced for extra strength.

Plywood

For sheathing repairs, use plywood the same thickness as the existing sheathing. Newer homes usually have 1/2-inch-thick plywood, while older homes may have planks that are 3/4 or even 7/8 inch thick. You can use standard CDX plywood or OSB sheets if you are sure they will not get wet. Pressure-treated plywood will resist rotting even if it gets soaked.

WSU

Also called ice-guard membrane, waterproof shingle underlayment (WSU) stays waterproof even after nails have been driven through it. After you remove the release paper, it sticks to the sheathing. There are various types, some with plastic coatings, some with mineral granules, and some with fiberglass reinforcement. It is common practice now to install a course of WSU along the lower edges of a roof, especially along eaves where ice dams could form. It is also sometimes used under valley flashing, where a roof meets a wall, and in other places where extra protection is desirable.

 

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