Sometimes your contractor will use words that are familiar to them but you have no idea what they are talking about. Here’s a list of terms that will help you understand your roof:


  • Asphalt: Asphalt is a sticky, black and highly vicious liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product; it is a substance classed as a pitch.
  • Air Barrier: The assembly of materials used in building construction to reduce or slow the passage of air into and out of the building.
  • Angled Fastners: Roofing nails and staples driven into decks at an angle – not perpendicular to the roof deck surface.
  • Apron Flashing: Metal flashing used at chimney or dormer fronts.
  • Base Sheet: First layer or base ply in low-slope multi-ply roofing systems.
  • Blow Offs: When shingles are subjected to high winds and are forced off a roof deck by the wind.
  • Buckling: A visible wrinkle or ripple in shingles or underlayments.
  • Blistering: Bubbles or pimples in roofing materials. Usually moisture related.
  • Cap Sheet: Top or final layer on low-slope roof systems.
  • Cant Strips: A triangular strip of material typically used on low-slope roofs for deflecting water away from flashing areas.
  • Counter Flashing: The metal or siding material installed over rooftop base flashing systems.
  • Deck/sheathing: The surface, usually plywood or oriented strand board (OSB), to which roofing materials are applied.
  • Dormer: A small structure projecting from a sloped roof, usually with a window.
  • Drip edge: An L-shaped strip (usually metal) installed along roof edges to allow water run off to drip clear of the deck, eaves and siding.
  • Eave: The horizontal lower edge of a sloped roof.
  • End Laps: When installing rolled products in roofing, the area where a roll ends on a roof and is overlapped by the next section of rolled material.
  • Fascia: A flat board, band or face located at a cornice’s outer edge.
  • Felt/Underlayment: A sheet of asphalt-saturated material (often called tar paper) used as a secondary layer of protection for the roof deck.
  • Fire Rating: System for classifying the fire resistances 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
  • Flange: The flat metal extending out on the roof from around flashing pieces, usually at chimneys and plumbing vents.
  • Flashing: Pieces of metal used to prevent the seepage of water around any intersection or projection in a roof system, such as vent pipes, chimneys, valleys and joints at vertical walls.
  • Gable Roof: Traditional roof style; two peaked roof planes meeting at a ridge line of equal size.
  • Granules: Crushed rock that is colored with ceramic coating and used as the top surface of shingles and other roofing material.
  • Hand-Sealing: The method to assure sealing of shingles on very steep slopes, in high-wind areas, and when installing in cold weather.
  • Hip and Ridge Cap Shingles: The final layer of the roof at the ridge or hip, used to ensure protection at the highest areas of the roof and to accentuate the natural beauty of the roof by adding dimension and depth.
  • Louvers: Slatted devices installed in a gable or soffit (the underside of eaves) to ventilate the space below a roof deck and equalize air temperature and moisture.
  • Mats: The general term for the base reinforcement material of shingles and certain rolled products.
  • Modified Bitumen: Rolled roofing membrane with polymer modified asphalt and either polyester or fiberglass reinforcement.
  • Nail Guide Line: A painted line on laminated shingles to aid in the proper placement of fasteners.
  • Nail Pop: When a nail is not fully driven or backs out of the roof deck, that can cause overlaying shingles to raise or can result in nail heads breaking through overlaying shingles.
  • Nesting: The practice of installing a second layer of shingles over existing shingles in reroof applications where the top edge of the new shingles is butted against the bottom edge of the existing shingles to help provide a smoother installation.
  • Oriented Strand Board (OSB): Roof deck panels (4 by 8 feet) made of narrow bits of wood, installed lengthwise and crosswise in layers, and held together with a resin glue. OSB often is used as a substitute for plywood sheets.
  • Open Valley: Valley installation using metal down the valley center.
  • Penetrations: Vents, pipes, stacks, chimneys-anything that penetrates a roof deck.
  • Pipe Boot: A pre-flashed flashing unit for flashing plumbing vent pipes or other round roof penetrations.
  • Plumbing Vents: A term used to describe plumbing pipes that projects through the roof plane.  Also called vent stacks.
  • Prevailing Wind: The most common direction of wind for a particular region.
  • Rafters: The supporting framing to which a roof deck is attached.
  • Rake: The inclined edge of a roof over a wall.
  • Ridge: The top edge of two intersecting sloping roof surfaces.
  • Roof Plane:  An even roofing area defined by having separate edges. One side of a gable, hip, or mansard roof.
  • Racking: The method of installing shingles in which shingle courses are applied vertically up the roof in a “straight up the roof” manner rather than across and up in a stair-step manner.
  • Self-Sealant: Sealant installed on the face or back of shingles. After installation on the roof, the sun’s heat will activate the sealant, sealing the shingles to each other.
  • Selvage: The non-exposed area on rolled roofing. Area without granules. Designed for nail placement and/or sealant.
  • Sheathing: The boards or sheet materials that are fastened to rafters to cover a house or building.
  • Shed Roof: Roof design of a single roof plane. Area does not tie into any other roofs.
  • Side Laps: The area on rolled material where one roll overlaps the rolled material beneath it. Also called selvage edge on rolled roofing.
  • Side Walls: Where a roof plane meets a vertical wall. For example: sides of dormers.
  • 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.
  • Square: The common measurement for roof area. One square is 100 square feet (10 by 10 feet).
  • Step Flashing: Individual pieces of sheet-metal material used to flash walls, around chimneys, dormers, and such projections along the slope of a roof. Individual pieces extend on the roof plane and up the vertical surface, and are overlapped and stepped up the roof as shingles are applied.
  • Tab: The bottom portion of traditional shingles separated by the shingle cut-outs.
  • Tear-Off: Removal of existing roofing materials down to the roof deck.
  • Telegraphing: When shingles reflect the uneven surface beneath them.
  • Transitions: When a roof plane ties into another roof plane that has a different slope
  • Truss: Engineered components that supplement rafters in many newer homes and buildings. Trusses are designed for specific applications and cannot be cut or altered.
  • Underlayments: Asphaltic, organic, fiberglass- or synthetic-based rolled materials designed to be installed under main roofing material to serve as added protection.
  • Valley: The angle formed at the intersection of two sloping roof surfaces.
  • Vapor: Term used to describe moisture-laden air.
  • Vapor Retarder: A material designed to restrict the passage of water vapor through a roof system or wall.
  • Vent: An opening designed to convey air, heat, water vapor, or other gas from inside a building or a building component to the outside atmosphere.
  • Warm Wall: The wall of a structure between the interior conditioned space and the exterior outside environment, used in roofing to determine how far up the deck to install waterproof underlayments at eaves.
  • Woven Valleys: The method of installing valleys in which shingles from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied up the roof.