Algae discoloration: A dark roof discoloration or streaking of roofing materials, caused by an airborne fungus, commonly called "gleo capsa".
APP: Atactic Polypropylene, a type of torch down rolled roofing material, generally used with flat roofs.
Architectural shingles: see laminated shingles
Asphalt: A bituminous waterproofing agent applied to roofing materials during the manufacturing process; see composition and underlayment.
Asphalt plastic roofing cement: An asphalt-based cement used to bond roofing materials. May also be referred to as flashing cement, mastic, or "bull".
Asphalt shingles: Roofing material that consists of a base material, which is coated with asphalt and granulated minerals.

Bargeboard: A board, often carved, hanging from the projecting end or rake end of a sloping roof.
Base flashing: That portion of the flashing attached to or resting on the roof deck to direct the flow of water onto the roof covering; see cap flashing.
Base material: Mat used as a base for asphalt coated roofing material. Most underlayments used over the years are organic mat. Most shingles are fiberglass mat.
Base sheet: First layer of paper applied usually 3 times thicker than ply sheets and coated.
Bird blocks: Holes cut at soffit for attic ventilation; see soffit vent.
Bituminous: bitumen is a mixture of hydrocarbons found in asphalt and tar or distilled from petroleum or oil. Frequently used in many roofing materials.
Blisters: Bubbles that may appear on the surface of asphalt roofing after installation.
Built-up roof {BUR}: A flat or low-slope roof consisting of multiple layers of asphalt and ply sheets {unsaturated felt}. Commonly referred to as "hot tar" or "tar and gravel".
Built-up Roofing: A method of applying a system composed of various amounts of roofing paper (base sheet and ply sheets) to achieve a waterproof membrane. Can be hot applied or cold applied.

Cap Sheet: Surface sheet for most built up roof systems. Made of asphalt products.
Cap flashing: That portion of the flashing attached to a vertical surface to prevent water from migrating behind the base flashing; sometimes referred to as counter flashing.
Caulk: To fill a joint with mastic, asphalt cement, or silicone sealer to prevent leaks.
Clearstory: The uppermost area of a roof plane that drops off without intersecting with another roof plane.
Closed cut valley: A method of valley treatment, during installation, in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed back from the valley centerline. Also referred to as lap cut valley.
Coating: A layer of viscous asphalt applied to the base material into which granules are imbedded.
Collar: Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe called a vent sleeve. Sometimes referred as boot.
Composition: Roofing material that consists of a base material, which is coated with asphalt and granulated minerals.
Concealed nail method: Application of roll roofing in which all nails are driven into the course of roofing and covered by a cemented, overlapping course. Nails are not exposed.
Counter flashing: See cap flashing; term commonly misused for base flashing.
Course: A row of roofing material {shingles, shakes} running horizontal {perpendicular to the drip line} the length of the roof.
Cricket: A pitched saddle construction at the back of the chimney or other vertical surface to deflect water around the chimney.
Cutout: The open portions of a 3-tab shingle between the tabs; also called the "key way".

Deck: The surface installed over the supporting framing members {trusses}, to which the roofing material is applied.
Dormer: A framed window unit projecting through the sloping plane of the roof.
Double coverage: Application of asphalt roofing, as such, as the lapped portions are at least wider than the exposed portion, resulting in two layers of roofing material over the deck.
Downspout: A pipe for draining water from the gutters; sometimes, called a "leader".
Drip edge: a non-corrosive non-staining material sometimes used along the eaves and rake edges to allow water run-off to drop clear of underlying decking and/or fascia.

Eaves: The horizontal, lower edge of a sloped roof.
Eaves flashing: Additional layer of roofing material applied at the eaves to prevent damage from water backup. Also called drip edge.
Edging strips: Boards nailed along eaves and rakes after cutting back existing wood shingles on a re-roof to provide secure rakes and eaves for applying new roofing materials.

Fascia: A relatively broad, flat, horizontal board, used to cover the rafter tails, at the eaves.
Fasteners: Staples or nails used to attach roofing material to roof deck. Galvanized staples are the preferred fastener for wood shakes or shingles. Nails are the preferred fastener for asphalt shingles.
Feathering strips: Tapered wood filler strips placed along the butts of old shingles or shakes to create a level surface when re-roofing over an existing wood shingle or shake roof.
Felt: Fibrous material saturated with asphalt and used as an underpayment or sheathing; see underlayment.
Fiberglass mat: Base material for asphalt composition or torch-down roofing material made from glass fibers.
Flashing: Pieces of metal or roll roofing used to prevent seapage of water around any intersection or projection in a roof such as vent pipes, chimneys, adjoining walls, dormers and valleys. Metal flashing should be minimum of 28 gauge with baked on enamel or a minimum of 26 gauge for galvanized metal. Note: the lower the number of the gauge, the thicker the material/metal.
Flat or low slope: Pitch of less than three (3) feet of rise over twelve (12) feet of run is considered a flat or low slope roof. Installation of composition roofing, at this minimum slope, is not recommended and can leak due to blow back.

Gable: The upper portion of a sidewall that comes to a triangular point, at the ridge of a sloping roof.
Gable roof: A type of roof containing sloping planes of the same pitch on each side of the ridge. Contains a gable at each end.
Gambrel roof: A type of roof containing two (2) sloping planes of different pitch on each side of the ridge. The lower plane has a steeper slope than the upper; contains a gable at each end.
Granules: Ceramic-coated, colored, crushed rock that is applied to the exposed surface of asphalt shingles.
Gutter: The trough that channels water from the eaves to the downspouts.

HEX shingles: Shingles that have the appearance of a hexagon, after installation.
Hip: The inclined external angle formed by the intersection of two (2) sloping roof planes; runs from the ridge to the planes.
Hip roof: A type of roof containing sloping planes on each side of the building; therefore doesn't form gables.
Hip shingles: Shingles used to cover the inclined external angle formed by the intersection of two (2) sloping roof planes. Also called hip and ridge.
Hot tar: Oil-based material applied first by heating to melting point in order to saturate individual ply of felt. Used on low slope or flat roofs. Can be covered with gravel in order to protect from harmful ultraviolet rays of sun. Also called tar and gravel.

Laminated shingles: Strip shingles made with fiberglass mat and asphalt. Also commonly called Architectural or dimensional shingles.
Lap: To cover the surface of one shingle or roll with another.
Leads: see Plumbing Vent Jack.
Low Slope Application: Method of installing asphalt shingles {or other material}, on slopes between 2 and 4 inches per foot. Involves decreasing the amount of material exposure {to the weather}, and by increasing the ply of underlayment.

Mansard roof: A type of roof containing two sloping planes of different pitch on each of four sides. The lower plane is much steeper that the upper, often approaching vertical. Contains no gables.
Mineral stabilizers: Finely ground limestone, slate, or other inert material added to roof coatings for durability and increased resistance to fire and weathering.
Mineral surfaced roofing: Asphalt shingles, roll roofing and torch down that are covered with granules.
Modified: Cap sheet or ply sheets that are manufactured with a modified rubber product. More tensile strength than regular asphalt products.
Nesting: A method of re-roofing with new asphalt shingles over old shingles in which the top edge of the new shingle is butted against the bottom edge of the existing shingle. While this is an accepted practice in certain locales, we don't recommend this installation; it hinders the roofing material and deck from breathing, therein lessening the life of your roof.
No-cutout shingles: Shingles consisting of a single, solid tab with no cutouts.

Open Valley: Method of valley construction in which shingles on both sides of the valley are trimmed along a straight line on each side of the valley. Shingles do not extend across the valley; see W valley.
Organic felt/mat: asphalt roofing base material manufactured from cellulose fibers.
Overhang: That portion of the roof structure that extends beyond the exterior walls of the building. See soffit.

Pallets: Wooden platforms used for storing and shipping bundles of shingles or tiles.
Pan: Flashing used on the upper side of a roof penetration such as a chimney or skylight; sometimes referred as back pan.
Pitch: The degree of roof incline, expressed as the ratio of the rise, in feet, to the span.
Plumbing Vent jack: Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening. Made of lead, rubber or metal. Referred to by various terms {pipe boot/jack, plumbing boot/jack and/or no-caulk or leads}.
Ply: Roofing sheets used in built up roofing systems, referred to as “felt.” The number of layers of roofing. Usually in reference to a low slope or flat type of roof. * caution - don't allow someone to talk you into applying more than one-ply of shingles. Roof won't breathe.
Polyester Membrane: Reinforcing membrane sheet used in the cold overlay system.

Rafter: The supporting framing member immediately beneath the deck, sloping from the ridge to the wall plate.
Rake: The inclined edge of a sloped roof over a wall from the eave to the ridge.
Ridge: The uppermost, horizontal external angle formed by the intersection of two slopes.
Roll Roofing: Asphalt roofing material manufactured in roll form; usually set aside for flat roofing or placed in valleys.

Saturated felt: An asphalt-impregnated felt used as an underlayment between the deck and the roofing material.
Sheathing: Exterior grade plywood or boards used as roof deck material.
Shed Roof: A roof containing only one sloping plane; it has no hips, ridges, valleys or gables
Single-ply roofing: A rubber roof membrane that is applied with or without adhesive and is sealed and fastened at the laps of the material. Laps are sealed with heat welding using special hot air welders or special lap adhesive. Heat welding is the preferred method.
Soffit: The finished underside of the eaves.
Soil stack: A vent pipe that penetrates the roof deck.
Square: A unit of roof measure covering 100 square feet.
Step Flashing: Flashing application method used whereby a vertical surface meets a slope.

Tab: The exposed portion of strip shingles defined by cutouts.
Tear-off: Removal of existing roof membrane.
Three-dimensional shingles: another reference for laminated or architectural shingles.
Three-tab shingle {3-tab}: the most economical type of asphalt shingle.

Underlayment: A layer of asphalt saturated {sometimes referred as tarpaper} which is installed over deck before shingles are installed, which provides additional protection for water intrusion.

Valley: The internal angle formed by the intersection of two sloping roof planes which serves as trough to funnel water off roof surface.
Vent: Any outlet for air that protrudes through roof deck such as a pipe or stack. A ridge vent or off-ridge vent is installed for the purpose of ventilating the underside of roof deck.

Woven valley: Method of valley construction in which shingles from both sides of the valley are woven together by overlapping alternate courses so as to prevent valley metal/flashing from being exposed.