Common Roofing Terms
Batten: A strip of wood usually set in or over the structural deck, used to elevate and/or attach a primary roof covering such as tile.
Building Code: Published regulations and ordinances established by a recognized agency prescribing design loads, procedures, and construction details for structures. Usually applying to designated jurisdictions (city, county, state, etc.). Building codes control design, construction, and quality of materials, use and occupancy, location and maintenance of buildings and structures within the area for which the code has been adopted.
Base flashing: That portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof covering.
Butt: The larger, exposed end of a shingle.
Chimney: Stone, masonry, prefabricated metal, or a wood framed structure, containing one or more flues, projecting through and above the roof.
Closed-Cut Valley: A method of valley application in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed back approximately 2 inches (51mm) from the valley centerline.
Coping: The covering piece on top of a wall which is exposed to the weather, usually made of metal, masonry, or stone. It is preferably sloped to shed water back onto the roof.
Copper: A natural weathering metal used in metal roofing; typically used in 16 or 20 ounce per square foot thickness (4.87 or 6.10 kg/sq m).
Course: Each row of shingles of roofing material that forms the roofing, waterproofing, or flashing system.
Cricket: A wood-framed structure that diverts water away from chimneys, walls or other vertical roof projections and penetrations; also called a saddle.
Deck: Plywood or oriented strand board (OSB) sheathing used as a base for securing roofing materials.
Dome: A roof that is shaped like a half-circle, or a variation of one.
Dormer: A small structure projecting from a sloped roof, usually with a window.
Downspout: A conduit used to carry runoff water from a scupper, conductor head, or gutter of a building to a lower roof level, or to the ground or storm water runoff system.
Drain: An outlet or other device used to collect and direct the flow of runoff water from a roof area.
Drip Edge: A metal flashing, or other overhanging component, with an outward projecting lower edge, intended to control the direction of dripping water and help protect underlying building components. A drip edge also can be used to break the continuity of contact between the roof perimeter and wall components to help prevent capillary action.
Eaves: On a sloped roof, the horizontal underside that projects out from the house wall.
Exposure: The part of a shingle that is exposed to the weather, usually less than half its actual length.
Eyebrow: A dormer, usually of small size, whose roof line over the upright face is typically an arched curve, turning into a reverse curve to meet the horizontal at either end. Also, a small shed roof projecting from the gable end of the larger, main roof area.
Fascia: Vertical roof trim located along the perimeter of a building, usually below the roof level, to cover the rafter tails at the eaves.
Fasteners: Any of a wide variety of mechanical securement devices and assemblies, including nails, screws, cleats, clips, and bolts, which may be used to secure various components of a roof assembly.
Fire Rating: System for classifying the fire resistance of various materials. Roofing materials are rated Class A, B or C, with Class A materials having the highest resistance to fire originating outside the structure.
Flashing: Metal pieces that keep water from seeping into intersections, such as valleys or joints at vertical walls, or around roof penetrations, such as chimneys or vent pipes.
Flat or low slope roof: A roof with a pitch of less than three feet of rise over a twelve-foot run; this type of roof needs a sealed system installation.
Gable Rake or Rake: The sloped edge of a roof over a wall.
Gutter: The trough that channels water from the eaves to the downspouts.
Hip: The external angle formed by the intersection of two sloping roof planes; from the ridge to the eaves.
Hip Starter: A hip tile is used to start the hip where it meets the eave.
Ice Dam: A mass of ice formed at the transition from a warm to a cold roof surface, frequently formed by refreezing melt water at the overhang of a steep roof, causing ice and water to back up under roofing materials.
Impact Resistance: the ability of a roofing material to resist damage (e.g., puncturing) from falling objects, application equipment, foot traffic, etc. The impact resistance of the roofing assembly is a function of all of its components, not just the membrane itself.
Interlock: Larger size clay tiles are produced by extruding a pad of clay which is passed between to molds to form the top and the bottom of the tile. The clay as it is extruded has water content that allows it to be malleable and due to the increased sophistication of today’s machinery the tile makers are able to control, within a very fine margin, the shrinkage as the moisture content is reduced before firing. The controlled drying eliminates the possibility of warpage and cracking.
Consequently the tile makers can build in side and head locks which allow the tiles to ‘interlock’ together.
The use of interlocks allow tiles to be laid at a lower pitch and if wind driven rain is forced between the first channel the design / height of the second channel is such that the moisture cannot penetrate the inner roof.
The first channel is also designed to that any moister that does penetrate this first line of deference can flow back onto the surface of the tile below.
These double channels are designed to allow movement, within strict tolerances, between the individual tiles as the roof assembly expands and contracts depending on the weather.
Joist: Any of the small timbers, metal or wood beams arranged parallel from wall to wall to support a floor, ceiling, or roof of a building.
Lap: That part of a roofing, waterproofing, or flashing component that overlaps or covers any portion of the same or another type of adjacent component.
Mansard: A decorative steep-sloped roof on the perimeter of a building.
Membrane: A flexible or semi-flexible material, which functions as the waterproofing component in a roofing or waterproofing assembly, and whose primary function is the exclusion of water.
Metal Flashing: Accessory components fabricated from sheet metal and used to weatherproof terminating roof covering edges. Frequently used as through-wall flashing, cap flashing (coping), counter flashing, step flashing, etc. (See Flashing.)
NRCA: National Roofing Contractors Association.
Open Valley: A method of valley construction in which the steep-slope roofing on both sides are trimmed along each side of the valley, exposing the valley flashing.
Overhang: That portion of the roof structure that extends beyond the exterior walls of a building.
Pan: the bottom flat part of a roofing panel which is between the ribs of the panel.
Pitch: Roof slope expressed as the ratio of a roof’s rise (vertical distance) to each foot of run (horizontal distance). A “4-in-12 pitch” means the roof rises 4 inches for every 12 inches of horizontal distance.
Rafters: The framework that supports the roof deck and roofing. On a sloped roof, these are the angled timbers on the underside.
Rake: The sloped edge of a roof at or adjacent to the first or last rafter.
Ridge or Ridge Cap: A material or covering applied over the ridge of a roof.
Ridge Starter: Ridge tile with a closed end that is used to start or finish a ridge at the gable.
Ridge Vent: A type of roof exhaust vent that ventilates the attic along the ridge or hip line where the roof deck has been cut back; works in conjunction with soffit vents under the eaves.
Ridge: The peak where two sloped roof sections meet.
Roof Ventilation: A static, wind- or power-operated system for removing hot air and moisture from the air under your roof. Includes ridge vents.
Roof Pitch or Roof Slope: Measured by rise in inches for each 12 inches of horizontal run: A roof with a 4-in-12 slope rises 4 inches for every foot of horizontal distance.
Skylight: A roof accessory, set over an opening in the roof, designed to admit light. Normally transparent, and mounted on a raised framed curb.
Slate: A hard, brittle metamorphic rock consisting mainly of clay minerals, used extensively as dimensional stone for steep roofing, and in granular form as surfacing on some other roofing materials.
Soffit: The finished underside of the eaves, or roof overhang, which can be enclosed or exposed.
Snow Guard: A series of devices attached to the roof in a pattern that attempts to hold snow in place, thus preventing sudden snow or ice slides from the roof.
Snow Load: A load imposed on buildings or other structures due to snowfall.
Square: A measurement of roof area that equals 100 square feet (an area 10' by 10’or 9.29 m²).
TRI: Tile Roofing Institute. Northern Roof Tiles recommends the Tile Roofing Institute’s
Design Criteria Manual for Moderate Climate Regions or Manual for Cold and Snow Regions installation procedure. Contact TRI @ www.tileroofinginstitute.org or (312) 670-4177
Underlayment: Asphalt-impregnated roofing paper that creates a secondary, watertight barrier between many roofing products and the roof deck.
Valley: The internal angle formed by the intersection of two sloping roof planes.
Vent: An opening designed to convey air, heat, water vapor or other gas from inside a building or a building component to the atmosphere.
Water Shield: A watertight barrier used to seal water out at the eaves and rakes, in valleys, and around chimneys and skylights.
Weep Holes: Small openings whose purpose is to permit drainage of water that accumulates inside a building component (e.g., a brick wall, skylight frame, etc.).