Roofing Terms

Roofing Terms

Asphalt (Composition) Shingles: These shingles are made of a base (organic or fiberglass) that is saturated with asphalt and coated with minerals on one side to resist weathering. The fiberglass shingles are more flexible and stronger than organic shingles. Shingles come in a wide variety of colors. The life expectancy of composition shingles depends on the rating (e.g., quality) and ranges from 20 years to lifetime. Most manufacturers will provide a material warranty, but only if it has been installed by a certified roofer.

ASTM: American Society for Testing and Materials. A voluntary organization concerned with development of consensus standards, testing procedures and specifications.

Base Flashing: That portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof covering.

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

Cedar Shake: Cedar shakes combine a traditional look with reliable, modern performance. Cedar shakes are a great choice for historic homes or homes in new developments with high appearance standards. Also, cedar shakes are an environmentally friendly option for consumers. The life expectancy of cedar shakes is up to 30 years, if quality materials are used. If the contractor uses commodity materials (low quality) or if the workmanship is poor, the life expectancy can drop to only 5 to 8 years. Another concern potentially associated with cedar shakes is that many communities will require you to install pressure-treated fire retardant shakes, which increases the cost of the materials.

Class “A”: The highest fire-resistance rating for roofing as per ASTM E-108. 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 are able to withstand moderate exposure to fire originating from sources outside the building.

Class “C”: Fire-resistance rating that indicates roofing materials are able to withstand light exposure to fire originating from sources outside the building.

Course: A row of shingles running the length of the roof.

Cricket: A peaked saddle construction at the back of a chimney to prevent accumulation of snow and ice and to deflect water around the chimney.

Cupola: A structure rising above the main roof. It is usually ornamental, but may be used for ventilation.

Deck: Also known as decking. The surface installed over the supporting framing members of a building. It is the structural “skin” of a roof over which roofing is applied. Most new homes have decking made of plywood. There are four main types of decking commonly used on residential roofing projects:

• Plywood: Plywood is strong, durable, and light. It comes in many grades with ratings from A to D. Use only exterior grade plywood for decking. The thickness of plywood depends on the spacing of the rafters.
• OSB: Oriented Strand Board (OSB) is cheaper than plywood, but not as strong as plywood, and does not hold nails as well as plywood. One side has a slip resistant coating and should be placed facing up.
• Tongue and Groove 2-by-6: If a roof will be seen from the inside (no ceiling installed), tongue and groove is used. It is a wood decking that provides great insulation without additional rigid roof insulation in moderate climates. Also, the boards can be painted or stained on the inside to match the interior.
• Step Sheathing: Step sheathing is used alone or in combinations with solid sheathing for installation of tiles or shakes. Step sheathing allows air circulations under the tiles by using 1-by-6 or 2-by-6 boards that are evenly spaced so that air can move under the tiles or shakes.

Dimensional/Architectural Shingle Dimensional shingles are very similar to composition shingles, but are thicker, and can be used to create a more custom appearance. Depending on the rating, dimensional shingles also have a much better lifespan.

Dormer: A framed window unit projecting through the sloping plane of a roof.

Downspout: 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