Aggregate: A surfacing or ballast for a roof system. Aggregate can be rock, stone, crushed stone or slag, water-worn gravel, crushed lava rock or marble chips.

Alligatoring: The cracking of the surfacing bitumen on a built-up roof, producing a pattern of cracks that resemble an alligator's hide.

Aluminum: A non-rusting metal used in roofing for metal roofing and the fabrication of gutter and flashings.

Apron Flashing: A flashing located at the low end of a curb or penetration.

Architectural Panel: A metal roof panel that usually requires solid decking underneath.

Architectural Shingle: Shingle that provides a dimensional appearance.

ARMA: Asphalt Roofing Manufacturers Association

Asphalt Felt: An asphalt-saturated and/or an asphalt-coated felt membrane.

Asphalt Roof Cement: The proper name for Plastic Cement and Flashing Cement. Asphalt roof cement consists of solvent-based bitumen, mineral stabilizers, and other fibers.

Ballast: A material installed over the top of a roof membrane to help hold it in place. Ballasts are loose laid and can consist of aggregate, or concrete pavers.

Barrel Roof: A roof configuration with a partial cylindrical shape to it.

Base Flashing (membrane base flashing): Plies of roof membrane material used to seal a roof at the vertical plane intersections, such as at a roof-wall and roof-curb junctures.

Base Ply: The primary ply of roofing material in a roof system.

Base Sheet: An asphalt-impregnated, or coated felt used as the first ply in some built-up and modified bitumen roof systems.

Batten: A strip of wood usually fastened to the structural deck for use in attaching a primary roof system such as tile.

Bay Window: A combination of three window units joined together that project outwards. The center unit is parallel to the wall and the two units each side are usually 45° or 90° (right angles) to the wall but can be any angle.

Bermuda Style Roof: A metal roof that has a step profile.

Birdstop: Barrier placed under the lower course of round spanish type tile, to keep birds from making nests in the roof.

Bitumen: Any of various flammable mixtures of hydrocarbons and other substances, occurring naturally or obtained by distillation from coal or petroleum, that are a component of asphalt and tar and are used for surfacing roads and for waterproofing.

Blind-Nailing: The use of nails so that they are not exposed to the weather in the finished roofing system.

Blister: A pocket of air trapped between layers of felt or membrane. Blisters are usually caused by water or other foreign substances.

Bonding Agent: A chemical agent used to create a bond between two layers.

Boot: A piece of material preformed to protect roof penetrations from dirt, moisture and other foreign and/or damaging substances.

Brake: A piece of equipment used for forming metal.

Buckle: A long, tented displacement of a roof membrane. Can occur over insulation and deck joints.

Built-in Gutter: A rain gutter built into the roof eave and supported by the roof structure.

Built-up Roof: A low-slope (or flat-seeming) roof covered with alternating layers of roofing felt and hot-mapped asphalt and topped off with a layer of gravel.

Built-up Roof Membrane: A roof membrane consisting of layers of bitumen, which serves as the waterproofing component, with plies of reinforcement fabric installed between each layer. The reinforcement material can consist of bitumen-saturated felt, coated felt, polyester felt or other fabrics. A surfacing is generally applied and can be asphalt, aggregate, emulsion or a granule-surfaced cap sheet.

Bundle: An individual package of shingles or shakes.

BUR: An acronym for Built-Up Roof. See Built-Up Roof.

Butyl Rubber: A butyl-based, synthetic elastomer.

Butyl Tape: A sealant tape used in numerous sealant applications such as sealing sheet metal joints.

Canopy: An overhang, usually over entrances or driveways.

Cant Strip: A triangular-shaped strip of material used to ease the transition from a horizontal plane to a vertical plane. Cant strips can be made of wood, wood fiber, perlite, or other materials.

Cap Flashing: A material used to cover the top edge of base flashings or other flashings.

Cap Sheet: A granule-surfaced membrane often used as the top ply of BUR or modified roof systems.

Caulk: A material with no elastomeric properties used for sealing joints.

Caulking: The act of sealing a joint or of material.

Castellated: Decorated with battlements (a parapet with alternating indentations and raised portions); also called crenellation. Buildings with battlements are usually brick or stone.

Chalk Line: (1) A string on a reel in a container that can hold chalk; (2) A line made on by pulling taut a string coated with chalk and snapping it.

Channel Flashing: Flashing with a built-in channel for runoff; used where roof planes intersect other vertical planes.

Chimney Cricket: Roof boarding and flashing used to create a pitched surface behind a chimney to deflect running water away from the back of the chimney.

Cladding: A material used to cover the exterior wall of a building.

Cleat: A continuous metal strip used to secure two or more metal roof components together. Commonly used along with coping or gravel stop on tall buildings.

Clerestory (Clearstory): A room that extends above an abutting roof section of a building.

Clip: A small cleat.

Clipped Gable: A gable cut back at the ridge in a small hip configuration.

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 installed over the top of those and then trimmed back approximately 2 inches from the valley centerline.

Coal Tar Pitch: A type of coal tar used in dead-level or low-slope built-up roofs. It is not for use in roofs exceeding ?" in 12" (2%) slope.

Cold Process Built-Up Roof: A roof consisting of multiple plies of roof felts laminated together with adhesives that usually come right out of a can or barrel and require no heating.

Conductor Box: An enlargement or catch basin at the top of a downspout or leader to receive rainwater from a gutter or scupper. (Also called conductor, leader head, leader box, collector, collector head, collector box, scupper head, catch basin, or bell.)

Conductor Head: A component used to direct water from a through-wall scupper to a downspout.

Combing Ridge: A term used to describe an installation of finishing slate at the ridge of a roof whereby the slates on one side project beyond to the apex of the ridge.

Composition Shingle: A type of shingle used in steep-slope roofing and generally comprised of weathering-grade asphalt, a fiber glass reinforcing mat, an adhesive strip, and mineral granules.

Condensation: The conversion of water vapor to liquid state when warm air comes in contact with a cold surface. (See also Dew Point.)

Contact Cements: Adhesives used to adhere or bond roofing components.

Coping: The piece of material used to cover the top of a wall and protect it from the elements. It can be constructed from metal, masonry, or stone.

Copper: A reddish-brown element that conducts heat and electricity very well. It is also used as a primary roof material as well as a flashing component. Copper turns a greenish color after being exposed to the weather for a length of time and appears in the middle of the Galvanic Series.

Copper Patina Solution: Chemical ingredients and solutions to pre-patina new copper.

Cornice: The portion of the roof projecting out from the side walls of the house.

Counter Batten: Wood strips installed vertically on sloped roofs over which horizontal battens are secured.

Counterflashing: The flashing which is imbedded at its top in a wall or other vertical structure and is lapped down over shingle flashing.

Courses: Horizontal rows of shingles or tiles.

Cove: In roofing, a heavy bead of sealant material installed at the point where vertical and horizontal planes meet. It is used to eliminate the 90? angle.

Creep: Movement of roof membrane causing the roof system to be deformed.

Cricket: A roof component used to divert water away from curbs, platforms, chimneys, walls, or other roof penetrations and projections.

Crocket: Decorative ornament usually on a spire or cupola.

Cross Ventilation: The effect of air moving through a roof cavity between vents.

Cupola: A relatively small roofed structure set on the ridge of a main roof area. Also known as a Crow's Nest.

Curb: (1) A raised member used to support skylights, HVAC units, exhaust fans, hatches or other pieces of mechanical equipment above the level of the roof surface, should be a minimum of eight inches (8") in height; (2) A raised roof perimeter that is relatively low in height.

Cure: A process by which a material is forms permanent molecular linkages by exposure to chemicals, heat, pressure, and/or weathering.

Cutback: Bitumen thinned by solvents that is used in cold-process roofing adhesives, roof cements, and roof coatings.

Cutout: The open area between shingle tabs. Also known as a "throat".

Dampproofing: Treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure.

Dead Level: Refers to a roof with no slope or pitch.

Dead Loads: Permanent, non-moving loads on a roof resulting from the weight of a building's components, equipment, and the roof system.

Deck: The structural component of the roof of a building which provides the substrate to which the roofing system is applied.

Deflection: The downward displacement of a structural member under load.

Degradation: A decline in the appearance, structure, or properties, of a material or substance.

Delamination: Separation of laminated layers of a material or system.

Dew Point Temperature: The temperature at which water vapor turns to liquid in cooling air at the existing atmospheric pressure and vapor content.

Dimensional Shingle: A shingle that is textured, or laminated to produce a three-dimensional effect. Also known as Laminated and Architectural Shingles. Please be aware that there are also shingles being produced that can be classified as Dimensional but not as Laminated. These shingles are comprised of a single piece of material rather than two different materials laminated together.

Dome: A roof with a partial-spherical shape.

Dormer: A framed projection through the sloping plane of a roof.

Double Coverage: Installing roofing so that there is twice the materials used resulting in a double layer of roofing.

Downspout: A conduit for carrying water from a gutter, scupper, drop outlet or other drainage unit from roof to ground level. Also known as a Leader Pipe.

Drainage: A roof system's design features, such as shape, slope and layout that affect its ability to shed water.

Drip Edge: A steel flashing bent at a 90 deg. angle that is placed along the outer perimeter of steep sloped buildings; used to help direct runoff water away from the building. Drip Edge resembles nosing except that it has an outwardly-angled bottom edge (preferably hemmed).

Dry Rot: Wood rot caused by certain fungi. Dry rot can result from condensation build-up, roof leaks that go untended, or from other problems. Dry rot will not remain localized. It can spread and damage any lumber touching the affected area.

Dynamic Load: Any moving load on a roof such as people and equipment. Wind can also be considered a Dynamic Load.

Eave: A roof edge that extends out past the exterior wall line.

Eaves-Trough: Another name for Gutter.

Edge Venting: The installation of vent material along a roof edge (e.g., Starter Vent) as part of a ventilation system. Edge vent material should be used in conjunction with other venting material (e.g., ridge vent) as it not intended for use by itself.

EPDM: A thermoplastic rubber with high tear strength that can be cross-linked by both peroxides and sulfur.

Exhaust Vent: A device used to vent air from the roof cavity with vents that are installed on or near the higher portions of the roof such as the ridge.

Expansion Cleat: A cleat designed to handle thermal movement of the metal roof panels.

Expansion Joint: A built-in separation between building sections to allow for free movement between the sections without damaging the buildings structural components.

Exposure: The portion of the membrane that is not overlapped by the succeeding ply or course. Or, the portion of the roofing material exposed to the weather after being installed.

Eyebrow: A small, shed roof protruding from the main roof or located on the side of a building below the level of the main roof.

Factory Seam: A splice/seam made in the roofing material by the manufacturer. It is preferable during installation to cut these splices out of the membrane.

Fascia: Vertical roof trim located along the perimeter of a building, usually below the roof level. Its use can be either decorative or for waterproofing.

Felt: A roofing sheet made of interwoven fibers. The fibers can be wood or vegetable for Organic Felts, glass fibers for fiberglass felts, polyester, or asbestos.

Ferrule: A metal sleeve used as a spacer to keep gutter from being beat up when secured to fascia with spikes.

Field of the Roof: Refers to the central part of a roof away from the perimeter.

Field Seam: A non-factory material seam made by joining overlapping seams together with adhesives, heat welders, or other means.

Fillet: A sealant material installed at horizontal and vertical planes to remove 90? angles.

Finial: A decorative ornament on top of a spire, peak, gable etc.

Fishmouth: An opening along the exposed edge of an installed ply of felt caused by shifting the ply during installation.

Flange: A projection edge of a roof component such as flashings, skylight frames, pre-manufactured curbs, etc. Usually refers to the part that sits on the roof surface.

Flash: To install flashing components.

Flashing: Components used to seal the roof system at areas where the roof covering is interrupted or terminated. For example, pipes, curbs, walls, etc. all have special components that, when correctly installed, will help prevent moisture entry into the roof system or building.

Flashing Cement: A trowelable mixture of solvent-based bitumen and mineral stabilizers.

Flashing Collar: A flashing component used to seal soil pipe vents, hot stacks or other roof penetrations.

Flat Lock: A type of interlocking two separate metal panels by folding one panel over on top itself and the folding the other down under itself and then hooking the panels together.

Fleece: Mats or felts used as a membrane backer and composed of fibers.

Flood Coat: The surfacing layer of bitumen into which aggregate is embedded on an aggregate-surfaced built-up roof. A flood coat is applied at an approximate rate of 45 to 60 pounds per square (100 square feet).

Fluid-Applied Elastomer: A liquid elastomeric material that cures to form a continuous waterproofing membrane.

Freeze Board: A board at the top of the house's siding, forming a corner with the soffit.

Gable: The triangular upper part of a wall closing the end of a ridged roof.

Gable Roof: A roof configuration that has gable ends.

Gable-On-Hip Roof: A roof configuration with hips coming up from the eave corners that terminate into a gable roof.

Galvalume: Trade name for a protective coating composed of aluminum zinc.

Galvanic Action: A reaction between different metals in the presence of an electrolyte.

Galvanized Steel: Steel that is coated with zinc to aid in corrosion resistance. Galvanized steel for use in roofing should be Hot-Dipped Galvanized with a G-90 coating.

Gambrel: A roof that has two different pitches.

Geodesic Dome: A geodesic dome uses a pattern of self-bracing triangles in a pattern that gives maximum structural advantage, thus theoretically using the least material possible.

Glass Felt: (1) In the manufacturing of roofing materials - a sheet comprised of bonded glass fibers prior to being saturated with bitumen; (2) short for asphalt or coal tar saturated fiberglass felt membrane.

Granule: A small aggregate, naturally or synthetically colored, used to surface cap sheets, shingles, and other granule-surfaced roof coverings.

Gutter: A channel (usually sheet metal) installed along the downslope perimeter of a roof to convey runoff water from the roof to the drain leaders or downspouts.

Headlap: The distance that the topmost ply of roofing felt or shingle overlaps the undermost ply or course.

Heat Welding: Fusing the seams of separate sections of roofing material together through the use of hot air or an open flame and pressure. Also known as heat seaming.

Hem: The edge created by folding metal back on itself. Metal is hemmed for safety and strength reasons.

Hip: The angle formed by the intersection of two sloping roof planes.

Hook Ladder: A ladder with a bracket at the top which hooks over the ridge of the roof, allowing the ladder to lay flat on the roofing material.

Hip Roof: A roof that rises by inclined planes on all sides of a building. The line where two adjacent sloping sides of a roof meet is called the Hip.

Hypalon: The trademark name for Chlorosulfonated Polyethylene (CSPE), which is a single-ply roofing material.

Ice Dam: Ice formed at the transition from a warm surface to a cold surface, such as along the overhang of a house. The build-up of ice is the result of ice or snow melting on the roof area over the warmer, living area of a building and then refreezing when it runs down and reaches the overhang.

Impact Resistance: A roof assembly?s ability to withstand the impact from falling objects such as hail.

Intake Ventilation: The part of a ventilation system used to draw fresh air in. Usually vents installed in the soffit or along the eaves of a building.

Interlocking Shingles: Shingles that lock together to provide wind resistance. See also T-Lock.

Joist: In a flat roof, a horizontal structural member over which sheathing is nailed.

Lap Cement: Asphalt-based roof cement used to adhere overlapping plies of asphalt roll roofing.

Lap Seam: Where two material that overlap are sealed together.

Lead: Metal used for flashing material.

Leader Head: A component used to direct water from a through-wall scupper to a downspout. Also known as a Collector Head.

Leader Pipe: A conduit for carrying water from a gutter, scupper, drop outlet or other drainage unit from roof to ground level. Also known as Downspout.

Loose-Laid Roof Membranes: Roofing material attached only at the perimeter and at penetrations and held in place by ballast, pavers, or other materials.

Mansard: A steep-sloped roof located at the perimeter of a building and usually used for decorative purposes.

Mansard Roof: A steeper roof that terminates into a lower sloped roof at its high point.

Membrane: The portion of the roofing system that serves as the waterproofing material. Can be composed of one material or several materials laminated together.

Metal Flashing: Roof components made from sheet metal that are used to terminate the roofing membrane or material along roof edges. Metal flashings are also used in the field of the roof around penetrations.

Mil: A unit of measure equal to 0.001 inches (1/1000 in.) used to indicate the thickness of a roofing membrane.

Mineral-Surfaced Roofing: Roofing materials with a top surface consisting of mineral granules.

Miter: The joint made by two diagonally cut pieces put together.

Modified Bitumen: a bitumen modified by one or more polymers such as Atactic Polypropylene (APP), styrene butadiene styrene (SBS).

Moisture Relief Vent: A vent installed through the roofing membrane to relieve moisture vapor pressure that has been trapped within the roofing system.

Monolithic: Used to describe something without seams; formed from a single material.

Nailer: A piece of lumber, preferably treated, that is secured to the deck, walls, or to premanufactured curbs. Nailers are used to receive fasteners for roof membranes. Generally, nailers are installed wherever it is necessary to secure base flashings and edge metal.

Nesting: To overlay existing shingles with new shingles and butt the top edge of the new shingle up against the bottom edge of the existing shingles.

Net Free Vent Area: The area permitting unrestricted air flow.

Night Seal: To temporarily seal the edge of a roof membrane in order to protect it from moisture entry. A.K.A. Night Tie-Off and Water Cut-Off.

Ninety-Pound: Granule-surfaced or fiber glass or organic felt roll roofing that has a mass of approximately 90 pounds per 100 square feet.

Open Valley: A valley where both sides of the roof are trimmed back from the centerline to expose the valley flashing material .

Organic Felt: An asphalt roofing base material manufactured from cellulose fibers.

Organic Shingle: An asphalt shingle reinforced with organic material manufactured from cellulose fibers.

Oriel Window: An oriel window is a window which projects from the main line of an enclosing wall of a building, carried on brackets or corbels, or supported by cantilevered floor structure.

Oriel Bay Window: A polygon shaped/3 sided oriel window.

OSB: Oriented Strand Board - Often used as roof sheathing in place of plywood.

Parapet: That part of any wall rising entirely above the roof.

Pitch Pocket: A flanged piece of flashing material placed around irregularly shaped roof penetrations on flat roofs.

R-Value: The measure of a material's resistance to heat flow. The higher a material?s R-value, the more it insulates.

Racking: The method of installing asphalt shingles where the shingles are installed straight up to the ridge rather than horizontally.

Rafter: The structural member extending from the downslope perimeter of a roof to the ridge or hip and is designed to support the roof deck and roof system components.

Raggle: A groove that is cut into the side of a vertical surface such as a wall or chimney that is used to insert a flashing element such as a reglet or counterflashing.

Rake: The sloped perimeter edge of a roof that runs from the eaves to the ridge. The rake is usually perpendicular to the eaves and ridge.

Rake-Starter: A starter strip placed along rake edges for use in asphalt shingle roofing.

Random slate roof: Slate roof installation with varying sizes or shapes of roofing slates

Reglet: A receiver, usually sheet metal, that counterflashings are attached to. Reglets can be surface-mounted, set in a raggle, or be part of the wall assembly.

Reinforced Membrane: A roofing membrane that has been strengthened by adding polyester scrims or mats, glass fibers or other material.

Re-roofing: The procedure of installing a new roof system.

Ridge: The line where two planes of roof intersect, forming the highest point on the roof that runs the entire length of the roof.

Ridge Cap: Material applied over the ridge or hip of a roof.

Ridge Course: The final course of roofing applied that covers the area where two or more roof planes intersect.

Ridge Vent: An exhaust venting device located at the ridge of a roof that works in conjunction with a starter or under eave soffit vent and is used to ventilate attics. Ridge vents and their cooperative starter or soffit vents should be installed at a 1:1 ratio in order to function properly.

Roof Assembly: A term used to describe all of the roof components including structural roof deck.

Roof Bracket: A metal bracket fastened to the roof decking to hold roof scaffolding in place.

Roof Covering: Shingles, tile, slate or metal and underlayment that protect the sheathing from weather.

Roof Curb: A frame used to structurally mount rooftop equipment such as HVAC units, exhaust fans, skylight, etc.; may be pre-constructed or constructed on site.

Roofer: An individual who installs roof systems and materials.

Roof Jack: (1) A steel bracket fastened to the roof that is used to support toe boards. (2) A term used to describe a Pipe Boot or Flashing Collar.

Roof Jack Vent: A roof vent used to ventilate a bathroom exhaust fan.

Roof Overhang: That portion of the roof that extends beyond the exterior wall line of the building.

Roof Seamer: (1) A mechanical device used to crimp metal roof panels and make the seams watertight. (2) A machine used to weld membrane laps of PVC (Thermoplastic) roofing material

Roof Pitch: The angle made by the roof surface plane with the horizontal plane and expressed as the amount of vertical rise for every twelve inch (12") horizontal run. For instance, a roof that rises four inches (4") for every twelve inch (12") horizontal run, is expressed as having a "four in twelve" slope; often written as "4:12." Expressed as a percentage, the slope would be 33%, which is equal to 4 divided by 12. Also known as the Slope of a roof.

Rosin: Non-asphaltic material used as slip sheets and sheathing paper in roof systems. Also referred to Rosin Paper and Rosin-Sized Sheathing Paper.

Row Lock: A brick laid on its face with the end surface visible in the wall face. Frequently spelled rolock.

Run: The horizontal dimension of a slope.

Saddle: (1) A type of flashing usually used in conjunction with step, counter, and apron flashings on steep slope roof systems. (2) A small, somewhat pyramid-shaped figure constructed in between sump drains that is used to direct run-off water toward the sump drains.

Saturated Felt: Felt that has been saturated with bitumen.

Scaffold: A temporary framework used to support people and material in the construction or repair of buildings and other large structures. It is usually a modular system of metal pipes, although it can be made out of other materials. Bamboo is still used frequently in Asia.

Scupper: An opening in a parapet wall that allows water to run off an interior roof or surface.
Scupper Box: A component used to collect water running through a scupper and directing it into a conductor head or downspout.

Sealant: Generic term for a multitude of materials used to seal joints or junctures against moisture or weather.

Self-Adhering Membrane: A type of membrane whose bottom surface will stick or adhere to a substrate without the use of an additional adhesive material.

Self-Sealing Shingle: Asphalt shingles with adhesive strips that will soften and stick to the following course of shingles when heated by the sun; used to help against wind uplift.

Selvage Edge: That portion of a granule-surfaced membrane that is designed to be overlapped by the following membrane course; usually two, four, or nineteen inches in width.

Sheathing: The rigid material (often on inch by six inch or one inch by 12 inch boards or sheets of plywood) which is nailed to the rafters, and to which shingles or other outside roofing materials are secured.

Shingle Flashing: Flashing that is laid in strips under each shingle and bent up the edge of a chimney or wall.
Side Lap: The longitudinal overlap of neighboring materials

Sill: The bottom framing member of a door or window opening.

Sill Flashing: Flashing material(s) used to waterproof the bottom framing member of a door or window opening.
Single Coverage: One layer of roofing material.
Single-Lock Standing Seam: A standing seam system with one overlapping interlock between two seam panels.
Single-Ply Membranes: Roofing membranes that are applied in one layer. Thermoplastic and thermoset membranes are usually Single-Ply Membranes.

Single-Ply Roofing: Roofing systems where the principal component consists of a single-ply membrane.

Skylight: A transparent or translucent item that is designed to admit light and set over a curbed opening in the roof.

Slate: A fine-grained metamorphic rock that splits into thin, smooth-surfaced layers used in steep slope roofing applications.

Slating Hook: A hook-shaped device used to secure roofing slate.

Slip Sheet: Sheeting material placed between roofing components to prevent those components from adhering to one another or to prevent material damage due to component incompatibility. Slip Sheets may be polyethylene, rosin-sized sheathing paper, or other material.

Slope: The number of inched of vertical rise in a roof per 12 inches of horizontal distance. Also referred to as pitch.

Soffit: The boards that enclose the underside of that portion of the roof which extends out beyond the sidewalls of the house.

Soffit Vent: An intake ventilation device located in the soffit. An exhaust vent should be installed on or near the ridge of the roof to work in conjunction with the soffit vent in order to properly ventilate the attic space. The ratio of intake vent area to exhaust vent area should be 1:1.

Soil Stack/Pipe: A pipe that penetrates a roof and is used to vent a building?s plumbing.

Solder: Any of various fusible alloys, usually tin and lead, used to join metallic parts.

Solvent Weld: To weld materials using a liquid solvent.

Spall: A chip, fragment, or flake from concrete or masonry.

Splash Guard: A fabricated metal pan or masonry block that is placed below a leader pipe or downspout and is used to help protect the roof membrane on a lower roof level or to prevent soil erosion when placed on the ground.

Splice: To join by overlapping along ends.

Splice Plate: A metal plate placed beneath the joint between two pieces of metal.

Sprayed Polyurethane Foam (SPF): A monolithic sprayed-on roofing material with a high R-value; formed when isocyanate ("A" component) and resin ("B" component) are mixed at a 1:1 ratio.

Square: One hundred square feet of roof, or the amount of roofing material needed to cover 100 square feet when properly applied.
Stack flashing: Pre formed roof flashing component for sealing plumbing vent pipe penetrations in roofing.

Stainless Steel: A highly corrosion resistant steel alloy containing either chromium, nickel, or copper.

Stair Step: The diagonal method of laying shingles.
Standing Seam: A type of metal roof system where the longitudinal seams on adjacent panels are turned up, overlapped and folded in various ways in order to prevent moisture entry and interlock the panels.

Starter Course: The primary course of roofing materials. The Starter course is installed along the downslope perimeter edge and usually covered by the first course of roofing.
Starter Strip: Strips of shingles (usually 3-Tab shingles with the tabs cut off) or roll roofing material that is laid along the eave line of the roof prior to the application of the first course of shingles. The starter strip is used to fill in the gaps created by shingle cutouts and joints.
Steep-Slope Roof: A roof with a slope exceeding 3 in 12 (25%). Deemed appropriate to receive water-shedding type roofing materials such as asphalt shingles, wood shakes and shingles, concrete or clay tile, etc.

Steeple: A tall tower forming the superstructure of a building, such as a church or temple, and usually surmounted by a spire.

Step Flashing: Separate pieces of metal flashing set into a masonry wall following the elevation of a sloped roof.
Storm collar/shield: A formed sheet metal covering installed on pre fabricated chimney flues that shields the flue roof flashing from excessive rain.

Straw Nail: Long-shanked nails used to fasten tile along hips and ridges.

Strip Flashing: Pieces of membrane material that are used to flash metal flashing flanges such as gravel stop.

Substrate: The surface that the roof is installed upon.

Tab: The portion of an asphalt shingle that is outlined by the cutouts.

Tar: A brown or black bituminous material, liquid or semi-solid in consistency, in which the predominating constituents are bitumens obtained as condensates in the processing of coal, petroleum, oil-shale, wood, or other organic materials.

Tear-Off: To remove a roof system down to the structural substrate.

Tear Resistance: A material?s ability to withstand tearing.

Termination: The sealed edges of a roof membrane.

Termination Bar: A bar, usually metal or vinyl, used to seal and anchor the free edges of a roof membrane.

Terne: Sheet iron or steel plated with an alloy of three or four parts of lead to one part of tin, used as a roofing material.

Terra Cotta: A semi-fired ceramic clay used in building construction.

Thatch Roof: A roof covering made with straw, palms, reeds or other natural growths that are bound together in order to shed water.

Thermal Stress: Stress to a roof system or component caused by expansion and / or contraction from temperature change.

Thermoplastic: (1) Becoming soft when heated and hard when cooled. (2) A thermoplastic resin, such as polystyrene or polyethylene.

Thermoset: A material that cannot be reshaped or formed by heating. EPDM and Butyl are thermosets.

Through-Wall Flashing: A material that extends through a wall and is used to direct water entering a wall cavity to the exterior of the structure.

Tie-In: The joining of two different roof systems.

Tie-Off: A watertight seal used to terminate roof membranes at system adjuncts, terminations, flashings, or substrates.

Tile: Flat Tile Flashing

Transverse Seam: The joint between the top of one metal roof panel and the bottom of the next panel, which runs perpendicular to the roof slope.

Transition: A meeting of two different roof slopes and roofing materials.

Tuck Pointing: To remove old and deteriorated mortar from between masonry blocks and replace it with new mortar.

Ultraviolet Light (UV): A form of luminous energy occupying a position in the spectrum of sunlight beyond the violet, and having wavelengths that do not enter the visible spectrum. UV rays accelerate deterioration of roof materials. Hence, the need for protective coatings.

Underlayment: A material installed over the roof deck prior to the application of the primary roof covering. Usually consists of fifteen or thirty pound organic felt but can also be self-adhering such as an ice and water protection membrane.

Valley: The less-than 180-degree angle where two sloping roof sections come together.

Valley Flashing: The flashing in valleys, extending in under to shingles on both sides.

Vapor Retarder: A material used to restrict the passage of water vapor through a roof assembly.

Vent: An opening or device used to permit air or vapors to exit an enclosed structure.

Wash,Chimney: The top flat section, or crown, of a chimney.

Water Guard: A turned up edge on valley metal or continuous wall flashing; used to prevent water migration under the roof system.

Weep Holes: Small holes used to permit moisture to drain that has gathered inside a building component.

Wind Clip: A clip that slips over the ends of tile, slate and other steep slope roofing materials in order to help prevent wind uplift damage.

Wire Tie: A system for attaching heavy steep slope roofing materials such as slate r tile by using wire fasteners in addition to or in place of nails.

Woven Valley: A valley construction whereby the valley has a woven look which is effected by overlapping alternate courses of shingles from both sides of the valley.

Zinc: A bluish-white, lustrous metallic element that is brittle at room temperature but malleable with heating. It is used to form a wide variety of alloys including brass, bronze, various solders, and nickel silver, in galvanizing iron and other metals, for electric fuses, anodes, and meter cases, and in roofing, gutters, flashings, edge metals and also for various household objects.

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