AGGREGATE- Crushed stone, slag or water-worn gravel that comes in a wide range of sizes. Used to surface built-up roofs.
ALGAE- Rooftop fungus that can leave dark stains on roofing.
ALGAE DISCOLORATION- A type of roof discoloration caused by algae, also called fungus growth.
ANGLED FASTENERS- Roofing nails and staples driven into decks at angles not parallel to the deck.
ARMA- Asphalt Roofing Manufacturer’s Association. Organization of roofing manufacturers.
ALLIGATORING- A characteristic of asphalt which occurs during the aging process in which the loss of volatile oils and the oxidation brought about by solar radiation produces a pattern of cracks which resemble an alligator hide, because of the limited tolerance of asphalt to thermal expansion or contraction.
ASPHALT- A dark brown to black, highly viscous, hydrocarbon produces from the residue left after the distillation of petroleum, used as a waterproofing agent.
ASPHALT EMULSION- Asphalt and additives or modifiers suspended in water.
ASPHALT CONCRETE PRIMER- Asphalt based primer used to prepare concrete and metal for asphalt sealant.
ASPHALT PLASTIC CEMENT- Asphalt based sealant material, meeting ASTM D4586 Type I or II. Used to seal and adhere roofing materials. Also called mastic, blackjack, roof tar, bull.
ASTM-The American Society for Testing and Materials. Organization that sets standards for a wide variety of materials, including roofing.
ATTIC- The open area above the ceiling and under the roof deck of a steep-sloped roof.
BALLAST- Weight used to protect single-ply roofs or to prevent blow off of systems which are not adhered. Typically #2 stone is used.
BACK NAILING- The practice of nailing roofing felts to the deck under the overlap, in addition to hot mopping, to prevent slippage of felts.
BACK SURFACING- Fine mineral matter applied to the back side of shingles to keep them from sticking.
BARE SPOTS- Small areas on a roof where the top membrane has become exposed to the elements.
BARREL ROOF- A roof design which in cross-section is arched.
BASE FLASHING- That portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof covering.
BATTENS- 1"x2"x4' wood strips nailed to the roof, upon which the field tile hangs.
BASE PLY- An asphalt-saturated and/or coated felt installed as the first ply with 4 inch laps in a built-up roof system under the following felts which can be installed in a shingle like fashion.
BATTEN PLATE- A formed piece of metal designed to cover the joint between two lengths of metal edge.
BITUMEN- Any of various mixtures of hydrocarbons occurring naturally or obtained through the distillation of coal or petroleum. (See Coat Tar Pitch and Asphalt)
BLISTER (BLISTERING)- An enclosed raised spot evident on the surface of a roof. They are mainly caused by the expansion of trapped air, water vapor, moisture or other gases. Blisters on a roof may involve only the coating, one or more plies of felt or may involve the whole membrane thickness.
BEAD- A semi-rounded strip (bead) of caulking material.
BEAM- A heavy main support structure, steel or wood running horizontally between columns or load bearing walls.
BLOW-OFFS- When shingles are subjected to high winds, and are forced off a roof deck.
BOND BREAKER- A substance or a tape applied between two adjoining materials to prevent adhesion between them.
BRAKE METAL- Sheet metal that has been bent to the desired configuration.
BUCKLING- When a wrinkle or ripple affects shingles due to organic underlayment.
BUILT-UP ROOF (BUR)– A roof consisting of multiple layers of reinforcing membrane and waterproofing materials.
BULB TEE- A specialized steel reinforcing member which support form boards and reinforces a gypsum deck, which when poured surrounds the Bulb-Tee.
BUNDLE- A package of shingles. There are 3, 4 or 5 bundles per square.
BUTT EDGE- The lower edge of the shingle tabs.
BUTTON CAP NAILS- Miami-Dade county specification fasteners for underlayment. This is the safest and most efficient way to adhere underlayment to the roof.
BUTTERFLY ROOF- A roof assembly which pitches sharply from either side toward the center.
C-CHANNEL- A structural framing member that, when viewed cross-sectionally, has the shape of a "C".
CANOPY- An overhanging roof.
CANT STRIP- A beveled support used at the intersection of the roof deck with vertical surfaces so that bends in the roofing membrane to form base flashings can be made without breaking the felts.
CAP FLASHING (COPING)- A material used to cover the top edge of base flashings or other flashings.
CAP SHEET- One to four plies of felt bonded and top coated with bitumen that is laid over an existing roof as a treatment for defective roofs.
CAPACITANCE METER- A device for locating moisture within a roof system by measuring the ratio of the change to the potential difference between two conducting elements that are separated by a non-conductor.
CATALYST- A substance that effects a chemical reaction and/or the rate at which a chemical reaction takes place. In roofing, catalysts are used in SPF roofing.
CAULK- A material with no elastomeric properties used for sealing joints.
CAULKING- The act of sealing a joint or of material.
CAVITATION- The vaporization of a liquid under the suction force of a pump which can create voids within the pump supply line. Cavitation will result in off-ratio foam in Sprayed Polyurethane Foam applications.
CEMENT- A general term for a variety of trowelable mastics, asphalt or tar, which are used during roof construction and repair.
CHALKING- The resulting dust which occurs on a surface due to Ultra Violet degradation.
CHANNEL FLASHING- Flashing with a built-in channel for runoff; used where roof planes intersect other vertical planes.
CHECKING- A pattern of surface cracks running in irregular lines. When found in the top pour of an asphalt built-up roof, is the preliminary stage of alligatoring.
CHLOROSULFONATED POLYETHYLENE- A synthetic, rubber-like thermoset material, based on high molecular weight polyethylene with suphonyl chloride, usually formulated to produce a self-vulcanizing membrane. Chlorosulfonated Polyethylene or CSPE. Best know as Hypalon™, it was developed in 1951 by DuPont.
CHEMICAL RESISTANCE- A materials ability to retain its properties when it comes into contact with certain chemicals.
CHOPPED GLASS AND EMULSION (CG&E)- A roof coating that consists of asphalt or clay emulsion and glass fiber reinforcement. The glass fiber comes in rope form and is mechanically chopped into small pieces and then mixed with the emulsion at the end of the spray gun so that the mixture is complete by the time the surfacing hits the top of the roof. Standard mixture is 9 gallons of emulsion and 3 pounds of glass fiber for every 100 square feet (36.5 Liters of emulsion and 1.5 kg of chopped glass for every 10 square meters). The CG&E coating is then usually surfaced with a fibered aluminum roof coating at rate of 1.5 gallons per 100 square feet (6 Liters per 10 square meters).
CLADDING- A material used to cover the exterior wall of a building.
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.
CLEAT- A device made of formed sheet metal which is mechanically attached onto which the fascia flange of a metal edge is snapped, so as to protect against wind uplift.
CLEARSTORY- A room that extends above an abutting roof section of a building.
CLIPPED GABLE- A gable cut back at the ridge in a small hip configuration.
CLOSED CUT VALLEY- A method of valley treatment in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed two inches from the valley centerline. The valley flashing is not exposed.
COAL TAR PITCH (Tar)- A bituminous material which is a by-product from the coking of coal. It is used as the waterproofing material for tar and gravel built-up roofing.
COAL TAR FELT- A roofing membrane saturated with refined coal tar.
COAL TAR ROOF CEMENT- A trowelable mixture of processed coal tar base, solvents, mineral fillers and/or fibers.
COATING- layer of any brush consistency product spread over a surface for protection.
COLD APPLIED- Products that can be applied without heating. These are in contrast to tar or asphalt which need to be heated to be applied.
COLD PATCH- A roof repair done with cold applied material.
COLLAR- A conical metal cap flashing used in conjunction with vent pipes or stacks usually located several inches above the plane of the roof, for the purpose of shedding water away from the base of the vent.
COMPATIBLE- Two or more substances which can be mixed or blended without separating, reacting, or affecting either material adversely.
COMPONENT- Any one part of an assembly associated with construction.
COMPOSITE BOARD- An insulation board which has two different insulation types laminated together in 2 or 3 layers.
CONDENSATION- The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.
CONDUCTOR- A pipe for conveying rain water from the roof gutter to a drain, or from a roof drain to the storm drain; also called a leader, downspout, or downpipe.
CONCEALED NAIL METHOD- Application of roll roofing in which all nails are driven into the underlying course of roofing and covered by a cemented, overlapping course. Nails are not exposed to the weather.
COOLING TOWER- A large device mounted on roofs, consisting of many baffles over which water is pumped in order to reduce its temperature.
CORE- A small section cut from any material to show internal composition. Cores are taken from the roof to verify the construction of the existing roof system. The deck is visable along with the insulation and the roof membrane.
CORNICE- A horizontal projecting course on the exterior of a building, usually at the base of the parapet.
CORROSION- The deterioration of metal by chemical or electrochemical reaction resulting from exposure to weathering, moisture, chemicals or other agents or media.
CONTROL JOINT- A control joint controls or accommodates movement in the surface component of a roof.
COPING- A construction unit placed at the top of the parapet wall to serve as a cover for the wall. Coping is typically metal, clay, or cement.
CORRUGATED- Folded or shaped into parallel ridges or furrows so as to form a symmetrically wavy surface.
COUNTER-FLASHING-The metal or siding material that is installed over roof-top base flashing systems.
COURSE- A single layer of building material.
CRAZING- A series of hairline cracks in the surface of weathered materials, having a web-like appearance.
CRICKET- A tapered construction detail that promotes drainage of water from behind an obstacle such as chimney.
CUPOLA- A decorative detail at the peak of a pitched roof sometimes used with ventilation or a lightening rod system.
CUPPING- When shingles are improperly installed over an existing roof or are over-exposed, they form a curl or cup.
CURB- A short wall or box built above the level of the roof to provide a means of flashing the deck equipment.
CUTBACK- Asphalt or tar that has been "cutback" with solvents and oils so that the material become fluid.
Roofing Terminology A-C