Flashing is an important part of your roof. It provides an extra layer of protection on areas of your roof that have a high chance of leaks. Usually, these are areas where the roofing shingles meet a rooftop penetration, such as a chimney or a vent stack.
Chimney flashing is one of the more obvious types of flashing. It is typically made of aluminum or steel. It looks like metal sheets that cover the roof shingles then angle up over the base of the chimney. Often, this flashing is covered with roofing tar or a similar material to ensure there is a tight seal. Damage occurs when the tar begins to crumble or if the flashing suffers corrosion. Occasionally hail may also damage chimney flashing.
Every roof has a vent pipe or flue somewhere on the roof. Moisture will get into the home through these vent pipes if they are not properly flashed. Vent pipe flashing is also typically made of metal, but instead of the sheet forming a right angle, it resembles a cone. There is a flange around the base of the cone to affix it to the roof. Storm damage, such as dents from hail or pieces being dislodged by wind, are the most common concerns.
There is flashing you likely can't see along the eaves of your roof. This is called drip edging. It is made of a waterproof membrane that is installed just below the shingles. Its job is to protect the eaves from water incursion. Drip edges may suffer damage if ice dams form at your eaves, but you can avoid this by keeping your gutters in good condition.
Not every roof requires saddle flashing. This type is reserved for architectural roofs that have additions like beams that extend beyond the main roof. You may see them on homes with attached patio canopies or pergolas, for example. The saddle is a metal flange that fits around the beam protrusion and then is sealed to the roof. Failure of the caulk that seals the edges is the most common type of damage.
Roof valleys are especially prone to leaks because of the way the water flows through the low areas. An extra layer of shingles is sometimes used to flash a valley, or there may be a V-shaped strip of metal flashing installed. Failure of the shingles or hail damage to metal is the most typical form of damage.
Contact a residential roof contractor to learn more.