Roofing Terms
Alligatoring
Alligatoring is a rooftop condition that occurs when the seams open up or the tar and gravel crack. This commonly happens to most tar and gravel roofs at the end of their lifespan, which is typically 10-12 years. In most cases, the roof should be replaced as soon as possible.
Deck
A roof's deck consists of sheathing and underlayment called roofing felt. The material used to finish the roof determines deck types. Most roofs require solid plywood or oriented strand board sheathing, while wood shingle and tile roofs need spaced board sheathing.
Dormers
Dormers create additional openings in your roof, which will affect your roof installation. One notable area is at the joints, which will need to be sealed with metal flashing. The style of dormer can also affect your roofing material. A shed dormer will decrease the slope of your roof over the opening. A gabled dormer often has higher pitches, which will shed water more easily.
Fascia Board
Fascia board is the exposed end of your roof. The gutter is normally attached to this.
Flashing
Flashing is the metal or vinyl edging that is placed along roof intersections, dormers, chimneys, vent pipes, and the edges of the roof. It helps guide water away from roof joints and toward gutters. Most flashing is made of galvanized steel or aluminum. Galvanized steel is inexpensive but needs occasional painting to prevent rusting. Aluminum is moderately priced and naturally resistant to decay. Copper flashing is often used on slate or tile roofs. Though it's the most expensive, copper flashing also lasts the longest.
Ridge Vent
A ridge vent is a special vent that sits along the top ridge of your roof. Like other vents, it allows your attic to breathe, but it sits underneath the roofing material, making it less visible than standard vents. Ridge vents help prevent ice dams and improper snow melt-off.
Roofing Felt
Roofing felt is the protective layer that sits between the roof sheathing and the shingles.
Roof Pitch and Slope
Roof pitch and roof slope are two terms that are often used interchangeably, but they actually mean different things. Slope is described in inches of vertical rise per foot of horizontal run. For example, a gently sloped roof that rises 4 inches for every 12 inches of house covering is said to have a 4-in-12 slope. Roof pitch is expressed as a fraction, the ratio of rise to the total span of the entire roof. The same gentle 4-in-12 slope translates into a 1:6 pitch.
Roof Surface
A roof's surface is the area on which all the roofing material sits. Roofing surfaces can be made of a variety of materials. The most common material in the U.S. is plywood with a covering of sheathing, felt, and roofing shingles.
Shingles
About 80% of homes in the U.S. have asphalt-shingle roofs. These are constructed of 12 x 36 inch sections that look like individual shingles when installed.
Soffits
Soffits are vents under the roof overhang that allow your attic to breathe.
Water Diverter
Similar to gutters, a water diverter is a piece of metal that helps control the flow of water as it drains from the roof.