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Roofing Terminology

  • Aggregate: Crushed stone, crushed slag, water-worn gravel used for surfacing a built up roofing system; any granular mineral material.

  • Application Rate: The quantity (mass, volume, or thickness) of material applied per area.

  • Algae: Gloeocapsa magma, blue - green algae that thrives in moist, humid environments and receives its nutrients from dust in the air. It is more likely to appear on the north and west sides of the house.

  • Apron Flashing: A flashing system that is located at the juncture of the top of a sloped roof and a vertical wall, chimney or steeper-sloped roof. This type of flashing makes a water tight junction, basically forming a right angle which starts up behind the cladding, comes down and out and over the roof. In the case of shingles, it comes out in between shingles.

  • Architectural Shingle: Shingle that provides a dimensional appearance

  • ARMA: Asphalt Roofing Manufacturers Association: A group of natural, fibrous, impure silicate materials used to reinforce some products.

  • Asphalt Roof Cement: Asphalt roofing cement is a composition of minerals, solvents, fillers and mostly asphalt. The combination of these ingredients makes it adhere to the asphalt shingle surface.

  • Bitumen: (1) a class of amorphous, black or dark colored, (solid, semi-solid, or) cementitious sub-stances, natural or manufactured, composed principally of molecular weight hydrocarbons, soluble in carbon disulfide, and found in asphalts, coal tars and pitches, wood tars and asphalts; (2) a generic term to denote any material composed principally of bitumen, typically asphalt or coal.

  • Blister: An enclosed pocket of air, which may be mixed with water or solvent vapor, between impermeable layers of felt or membrane, or between the membrane and substrate.

  • Bond: The adhesive and/or cohesive forces holding two components in positive.

  • Bond, Chemical: Adhesion between surfaces, usually of similar materials, resulting in a chemical reaction or cross-linking of polymer chains.

  • Bond, Mechanical: Adhesion between surfaces resulting from interfacial forces or interlocking.

  • Bonding Agent: A chemical substance applied to a suitable substrate to create bonding and a succeeding layer.

  • Boot: (1) A covering made of flexible material, which may be pre-formed to a particular, used to exclude dust, dirt, moisture, etc. from around a penetration; (2) material used to form a closure, sometimes installed at inside and outside.

  • Built-Up Roof Membrane (BUR): A continuous, semi-flexible multi-ply roof membrane, of plies or layers of saturated felts, coated felts, fabrics, or mats between alternate layers of bitumen are applied. Generally, built-up roof membranes are with mineral aggregate and bitumen, a liquid-applied coating, or a surfaced cap sheet.

  • Butt Joint: A joint formed by adjacent, separate sections of material, such as where neighboring pieces of insulation abut.

  • Butyl: Rubber-like material produced by copolymerizing isobutylene with isoprene. Butyl may be manufactured in sheets, or blended with other materials to make sealants and adhesives.

  • Butyl Coating: An elastomeric coating system derived from polymerized isobutylene. Coatings are characterized by low water vapor permeability.

  • Butyl Rubber: A synthetic elastomer based on isobutylene and a minor amount of. It is vulcanizable and features low permeability to gases and water vapor.

  • Cap Flashing: Usually composed of metal, used to cover or shield the upper edges of membrane base flashing, wall flashing, or primary flashing. (See Flashing and.)

  • Cap Sheet: A granule-surface coated sheet used as the top ply of some built-up or bitumen roof membranes and/or flashing.

  • Caulk: A material (usually a composition of vehicle and pigment) used for/sealing joints or junctures, where no elastomeric properties are required. (See.)

  • Caulking: (1) The physical process of sealing a joint or juncture; (2) Sealing and weather-tight the joints, seams, or voids between adjacent units by filling with sealant.

  • Chalk Line: A line made by snapping a taut string or cord dusted with chalk. Used for alignment purposes.

  • Chalking: The degradation or migration of an ingredient, in paints, coatings, or other.

  • Chemical Resistance: The ability to withstand contact with specified chemicals without significant change in properties.

  • Chlorinated Polyethylene (CPE): A thermoplastic material, used for single-ply roof, composed of high molecular weight polyethylene which has been vulcanized; a process that yields a flexible rubber-like material.

  • Clip: An individual (discrete) cleat.

  • Coated Base Sheet: A felt that has previously been saturated (filled or impregnated) asphalt and later coated with harder, more viscous asphalt, which greatly improves its impermeability to moisture.

  • Cold Process Built-Up Roof: A continuous, semi-flexible roof membrane, consisting of a ply or plies of felts, mats or other reinforcement fabrics that are laminated together with alternate layers of liquid-applied (usually asphalt-solvent based) roof cements or installed at ambient or a slightly elevated temperature.

  • Coping: The covering piece on top of a wall which is exposed to the weather, usually of metal, masonry, or stone. It is preferably sloped to shed water back onto the.

  • Copper: A natural weathering metal used in metal roofing; typically used in 16 or 20per square foot thickness (4.87 or 6.10 kg/sq m).

  • Counterflashing: Formed metal sheeting secured on or into a wall, curb, pipe, rooftop, or other surface, to cover and protect the upper edge of the membrane base or underlying metal flashing and associated fasteners from exposure to the.

  • Course: (1)The term used for each row of shingles of roofing material that forms the, waterproofing, or flashing system; (2) One layer of a series of materials applied to a surface (e.g., a five-course wall flashing is composed of three applications of roof with one ply of felt or fabric sandwiched between each layer of roof cement.)

  • Cricket: An elevated roof substrate or structure, constructed to divert water around.

  • Curb: (1) A raised member used to support roof penetrations, such as skylights, equipment, hatches, etc. above the level of the roof surface; (2) A raised perimeter relatively low in height.

  • Cure: A process whereby a material is caused to form permanent molecular linkages due to exposure to chemicals, heat, pressure, and/or weathering.

  • Cure Time: The time required to effect curing. The time required for a material to reach desirable long-term physical characteristics.

  • Dead Valley: A point on a roof where two slopes meet in such a way that makes it difficult for water to run off.

  • Dew Point Temperature: The temperature at which water vapor condenses in cooling at the existing atmospheric pressure and vapor content. Cooling at or below the point will cause condensation.

  • Double Coverage: Application of asphalt, slate, or wood roofing such that the lapped is at least 2 inches (51mm) wider than the exposed portion, resulting in two layers of roofing material over the deck.

  • Double Lock Standing Seam: A standing seam that utilizes a double, overlapping between two seam panels. (See Standing Seam.)

  • Downspout: a conduit used to carry runoff water from a scupper, conductor head, or 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 roof area.

  • Drip Edge: A metal flashing, or other overhanging component, with an outward lower edge, intended to control the direction of dripping water and help underlying building components. A drip edge also can be used to break the contact between the roof perimeter and wall components to help prevent action.

  • Dry-In or Dry-In Felt: Usually the underlayment or the process of applying the felt for steep roofing.

  • Dutch Roof: A Dutch gable roof or gablet roof (in Britain) is a roof with a small gable at the top of a hip roof. The term Dutch gable is also used to mean a gable with parapets. Some sources refer to this as a gable-on-hip roof.

  • Edge Stripping: Membrane flashing strips cut to specific widths used to seal/flash edge metal and the roof membrane.

  • Edge Venting: The practice of providing regularly spaced or continuously protected(e.g., louvered) openings along a roof edge or perimeter, used as part of a ventilation to dissipate heat and moisture vapor.

  • End Lap: The distance of overlap where one ply, panel, or piece extends beyond the end of the immediately adjacent underlying ply, panel, or piece. 

  • EPDM: Ethylene Propylene Diene Monomer (See also Ethylene Propylene Diene.)

  • Ethylene Propylene Diene Terpolymer (EPDM) (Rubber Roof): Designated nomenclature of ASTMA terpolymer of ethylene, propylene, and a diene. EPDM material is a synthetic elastomer.

  • Expansion Joint: A structural separation between two building elements that allows movement between the elements without damage to the roofing or waterproofing.

  • Exposed-Nail Method: A method of asphalt roll roofing application in which all nails driven into the adhered, overlapping course of roofing. Nails are exposed to the weather.

  • Exposure: (1) The traverse dimension of a roofing element or component not by an adjacent element or component in a roof covering. For example, the of any ply in a built-up roof membrane may be computed by dividing the felt minus 2 inches (51mm) by the number of shingled plies; thus, the exposure of 36(914mm) wide felt in a shingled, four-ply membrane should be approximately/2 inches (216mm)(See Figure 3) ; (2) the dimension of sidewall or roofing covering is not covered or overlapped by the upslope course of component. The typical for a standard-size, 3-tab shingle is 5 inches (127mm), depending upon specifications. 

  • Factory Seam: A splice/seam made by the manufacturer during the assembly of materials into large sheets.

  • Fasteners: Any of a wide variety of mechanical securement devices and assemblies, nails, screws, cleats, clips, and bolts, which may be used to secure various types of a roof assembly.

  • Felt: A flexible sheet manufactured by the interlocking of fibers through a combination of mechanical work, moisture, and heat. Roofing felts may be manufactured principally with wood pulp and vegetable fibers (organic felts), asbestos fibers (asbestos felts),fibers (fiberglass felts or ply sheet), or polyester fibers.

  • Field Seam: A splice or seam made in the field (not factory) where overlapping sheets joined together using an adhesive, splicing tape, or heat- or solvent-welding.

  • Fire Resistance: The ability of a building component to act as a barrier to the spread of fire and confine it to the area of origin.

  • Flame Retardant: A substance which is added to a polymer formulation to reduce its tendency to burn.

  • Flashing: Components used to weatherproof or seal the roof system edges at, penetrations, walls, expansion joints, valley, drains, and other places the roof covering is interrupted or terminated. For example, membrane base covers the edge of the field membrane, and cap flashings or counter flashings the upper edges of the base flashing.

  • Flashing Cement: As used by the roofing industry, an ASTM D 2822 Type II roof that is a trowelable mixture of solvent-based bitumen and mineral stabilizers may include asbestos or other inorganic or organic fibers. Generally, flashing is characterized as vertical-grade, which indicates it is intended for use on surfaces. (See Asphalt Roof Cement and Plastic Cement.)

  • Flashing Collar: (Sometimes referred to as a Roof Jack or Flashing Boot) an accessory used to cover and/or seal soil pipe vents and other penetrations.

  • Gable Roof: A gable roof is the classic, most commonly occurring roof shape in those parts of the world with cold or temperate climates. It consists of two roof sections sloping in opposite directions and placed such that the highest, horizontal edges meet to form the roof ridge.

  • Gambrel Roof: A gambrel or gambrel roof is a usually symmetrical two-sided roof with two slopes on each side. The upper slope is positioned at a shallow angle, while the lower slope is steep.

  • Galvalume: Trade name for a coating, used over metal, which is composed of aluminum for corrosion protection.

  • Galvanized Steel: Steel coated with zinc for corrosion resistance.

  • Granule: (Also referred to as Mineral or Ceramic Granule) Opaque, natural, or colored aggregate commonly used to surface cap sheets, shingles, and granule-surfaced roof coverings.

  • Gravel Stop: A low profile upward-projecting metal edge flashing with a flange along the roof side, usually formed from sheet or extruded metal. Installed along the edge of a roof to provide a continuous finished edge for roofing material. Acts as a stop during mop application of hot bitumen along a perimeter edge.

  • Gutter Apron: A Specialized Drip Edge designed to direct water into the gutter system. Gutter Apron is installed over the roof edge and hangs in the gutter.

  • Headlap: The distance of overlap between overlapping shingles or tiles. 

  • Heat Welding: Method of melting and fusing together the overlapping edges of sheets or sections of polymer modified bitumen, thermoplastics or some thermoset roofing membranes by the application of heat (in the form of hot air open flame) and pressure.

  • Hip Roof: A type of roof where all sides slope downwards to the walls.

  • Ice & Water Shield: Ice and water shield, is a waterproof roof underlayment membrane developed to protect vulnerable areas on a roof from ice and water damage.  These areas include the eaves, valley, chimneys and all penetrations. Ice and water shield is made with polymer-modified bitumen. The self-adhesive backing surface of the membrane bonds to the roofs deck.

  • Ice Dam: A mass of ice formed at the transition from a warm to a cold roof surface, formed by refreezing meltwater at the overhang of a steep roof, causing ice water to back up under roofing materials.

  • Infrared Thermography: A practice of roof system analysis where an infrared camera is used to measure the temperature differential of a roof surface to locate areas of wet or moist insulation.

  • Insulation: Any of a variety of materials designed to reduce the flow of heat, either from or into a building.

  • Intake Ventilation: The fresh air that is drawn into a passive ventilation system typically installed in the soffit or eave of a roof.

  • Interlayment: A felt, metal, or membrane sheet material used between courses of sloped roofing to improve the weather- and water-shedding characteristics of the  roof covering during times of wind-driven rain and snow. Typically used with shakes.

  • Lap: That part of a roofing, waterproofing, or flashing component that overlaps portions of the same or another type of adjacent component.

  • Lap Seam: Occurs where overlapping materials are seamed, sealed, or otherwise.

  • Layover: See Re-Roof

  • Leak Barrier: See Ice and Water Shield

  • Lichen: Lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens have properties different from those of their component organisms. It doesn't trap as much water against the surface of the roof as moss, but it can be acidic and has strands that can penetrate into the shingles. Lichen can sometimes be confused with hail damage because of the granule loss.

  • Mansard Roof: A decorative steep-sloped roof on the perimeter of a building.

  • Mastic: See Asphalt Roof Cement.

  • Material Safety Data Sheets (MSDS): A written description of the chemicals in a, and pertinent other data including such things as safe handling and procedures. In accordance with OSHA regulations, it is the manufacturer’s to produce an MSDS and the employer’s responsibility to communicate contents to employees.

  • Mechanically-Fastened Membranes: Generally used to describe membranes that been attached at defined intervals to the substrate. Mechanical fastening may be with various fasteners and/or other mechanical devices, such as plates or.

  • Membrane: A flexible or semi-flexible material, which functions as the waterproofing in a roofing or waterproofing assembly.

  • Metal Flashing: Accessory components fabricated from sheet metal and used to terminate roof covering edges. Frequently used as through-wall, cap flashing (coping), counterflashing, step-flashing, etc. (See Flashing.)

  • Metal Valley: A metal valley is a pre-bent roof material that protects vulnerable areas of your roof prone to water damage or leaking. The proper way to install a metal valley is on top of an ice and water shield, creating an effective passageway for rainwater into your gutter and keeping your roof dry and well-protected.

  • Mineral-Surfaced Roofing: Roofing materials whose surface or top layer consists of granules.

  • Model 750: A three sided louver to allow more air to flow through the vent which in turn will remove more heat and moisture from an attic.

  • Modified Bitumen: (1) A bitumen modified through the inclusion of one or more (e.g., a tactic polypropylene, styrene butadiene styrene, etc.)

  • Mopping: The application of hot bitumen, with a roofer’s hand mop or mechanical, to the substrate or to the felts of a bituminous membrane.

  • Nailer: (Commonly referred to as Blocking) A piece or pieces of dimensional lumber/or plywood secured to the structural deck or walls, which provide a receiving for the fasteners used to attach membrane or flashing. Generally, it is that nailer’s be the same thickness as the adjacent insulation, and may be treated with a non-oil-borne preservative, and be of sufficient width to fully support horizontal flashing flange of a metal flashing (where used).

  • Nailing: The application of nails. May be: (1) exposed nailing of roofing wherein nails are exposed to the weather; (2) concealed nailing of roofing wherein nail heads concealed from the weather by an overlapping material.

  • Nailing Zone: The area of the shingle where the nails are to be installed. The nailing zone helps eliminate human error, in such as high or low nailing, and speeds up the installation process.

  • Neoprene: A synthetic rubber (polychloroprene) used in liquid-applied and applied elastomeric roof membranes or flashings.

  • NRCA: National Roofing Contractors Association

  • Parapet Wall: A barrier that is an extension of the wall at the edge of a roof, terrace, balcony, walkway or other structure.

  • Partially-Attached: A roofing assembly in which the membrane has been “spot” to a substrate, usually with an adhesive or a mechanical device.

  • Penetration: Any object passing through the roof.

  • Pipe Boot: Prefabricated flashing piece used to flash around circular pipe.

  • Polymer: A natural or synthetic chemical compound of high molecular weight, or of such compounds, formed when monomers (small individual molecules) are to form large long-chain molecules.

  • Polyvinyl Chloride (PVC): A synthetic thermoplastic polymer prepared from. PVC can be com-pounded into flexible and rigid forms through the plasticizers, stabilizers, fillers, and other modifiers; rigid forms are used in pipes; forms are used in the manufacture of sheeting and roof membrane materials.

  • Ponding: The excessive accumulation of water at low-lying areas on a roof.

  • Positive Drainage: the drainage condition in which consideration has been designed for all loading deflections of the deck, and additional roof slope has provided to ensure drainage of the roof area within 48 hours of rainfall, during drying conditions.

  • Power Vent: Electric-powered attic vents use a thermostat and humidistat control to monitor heat and moisture buildup inside the attic. Featuring a low-profile dome, the power attic vent is unobtrusive when installed on the roof slanting away from the front of your home. It's an efficient option to replace wind turbines or roof pots already in place.

  • Primer: (1) A thin, liquid-applied solvent-based bitumen that may be applied to improve the adhesion of subsequent applications of bitumen; (2) a material is sometimes used in the process of seaming single-ply membranes to prepare surfaces and increase the strength (in shear and peel) of the field splice.

  • Re-Cover: The addition of a new roof membrane or steep-slope roof covering over a portion of an existing roof assembly. This process does not involve removal of the existing roofing.

  • Re-Roof: Re-roofing or Layover is a process in which the second set of shingles is layered over an existing set of shingles on a roof without taking off the existing layer of old shingles on a roof.

  • Ridge Cap: A material or covering applied over the ridge of a roof.

  • Ridge Course: The last or top course of roofing materials, such as tile, roll roofing, etc., that covers the ridge and overlaps the intersecting field roofing.

  • Ridge Vent: A ventilator located at the ridge that allows the escape of warm and/or air from the attic area or rafter cavity. Most ridge vents are either metal or flexible, shingle-over type.

  • Roll Roofing: Smooth-surfaced or mineral-surfaced, coated, prepared felts.

  • Roof Assembly: An assembly of interacting roof components (includes the roof deck, retarder [if pre-sent], insulation, and roof covering).

  • Roof Curb: Raised frame used to mount mechanical units (such as air conditioning or fans), skylights, etc.

  • Roof Seamer: Machine that crimps neighboring metal roof panels together, or that laps membrane sheets together using heat, solvent, or dielectric energy.

  • Roof Slope: The angle a roof surface makes with the horizontal, expressed as a ratio of units of vertical rise to the units of horizontal length (sometimes referred to as run). English units of measurement, when dimensions are given in inches, the slope may be expressed as a ratio of rise to run, such as 4:12, or as a percent.

  • Roof System: A system of interacting roof components, generally consisting of primary roof covering and insulation (not including the roof deck) to weatherproof and, sometimes, to improve the building’s thermal.

  • Seam: A joint formed by mating two separate sections of material.

  • Shed Roof: A shed style roof, also known as a skillion or lean-to roof, is a roof that slopes down in one direction. It is flat with a steep slope

  • Side Lap: The continuous longitudinal overlap of neighboring like materials. 

  • Single-Lock Standing Seam: A standing seam that utilizes one overlapping interlock to seam panels, in contrast with the double interlocking used in a double seam.

  • Single-Ply Membranes: Roofing membranes that are field applied using just one layer membrane material (either homogeneous or composite) rather than multiple layers.

  • Single-Ply Roofing: A roofing system in which the principal roof covering is a single flexible membrane, often of thermoset, thermoplastic, or polymer modified compounds.

  • Single-Ply System: Generally, there are six types of single-ply roofing systems:

  1. Fully-adhered
    2) Loose-laid
    3) Mechanically-fastened
    4) Partially-adhered
    5) Protected membrane roof
    6) Self-adhering

  • 634 Broan Vent: Steel roof cap for 6" round duct for range hoods, losone fans, and bath ventilation fans, black

  • 636 Broan Vent: Steel roof cap for 3" or 4" round duct for bathroom ventilation, laundry ventilation, home gym, etc…

  • Split Boot: An adjustable rubber pipe boot flashing that simplifies the replacement of deteriorating flashings around electrical masts on shingle roofing.

  • SquareOne roofing square, or square of roofing shingles, is the amount of material needed to cover 100 square feet of roof area

  • Standing Seam: A metal roof system that consists of an overlapping or interlocking that occurs at an upturned rib. The standing seam may be made by turning up edges of two adjacent metal panels and overlapping them, then folding them in a variety of ways.

  • Starter or Starter StripA starter strip is an asphalt based shingle utilized to waterproof the eave and rake edges of your home during a re-roof.

  • Static Vent: Static ventilation uses non-powered ventilation products to cool the home. These products work with the natural flow of air and temperature. Here's how static ventilation works: As air heats up, it rises and becomes less dense. The wind movement around and over a home creates areas of low and high pressure.

  • Steep-Slope Roofing: A category of roofing that includes water shedding types of roof installed on slopes exceeding 3:12 or 25%.

  • Step Flashing: Step flashing is a rectangular piece of flashing bent 90 degrees in the center. It is used for roof to wall flashing. Multiple pieces of the flashing will be installed in layers with shingles to ensure the water flows away from the wall.

  • Styrene Butadiene Rubber (SBS): High molecular weight polymers having rubber-like, formed by the random copolymerization of styrene and butadiene. Used in class 4 impact rated shingles and manufacture’s hip and ridge shingles.

  • Substrate: The surface upon which the roofing or waterproofing membrane is applied (e.g., in roofing, the structural deck or insulation).

  • Synthetic Underlayment: Synthetic underlayment is a roofing accessory created by weaving/spinning together polypropylene or polyethylene and a polymer to form an all-over protective barrier to put between the roofing material and the roof deck. The purpose of underlayment is to absorb asphalt from the shingle and provide an extra level of water resistance.

  • Tapered Edge Strip: A tapered insulation strip used to (1) elevate and slope the roof to the perimeter and at curbs, and (2) provide a gradual transition from one layer to another.

  • Taping: (1) The technique of connecting joints between insulation or deck panels with tape; (2) the technique of using self-adhering tape-like to seam or splice single-ply membranes.

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

  • Termination: The treatment or method of anchoring and/or sealing the free edges of membrane in a roofing or waterproofing system.

  • Thermal Barrier: A material applied over polyurethane foam designed to slow the rise of the foam during a fire and delay its involvement in the fire. Thermal for use with SPF must have a time rating of not less than 15 minutes.

  • Thermal Block: A compression-resistant insulation block installed between the steel and the panel to maintain insulation value.

  • Tobacco Juicing: A result of water solubles leaching from the oxidized surface of exposed asphalt and/or air contaminants and may be seen on all asphalt-based products.

  • Thermoplastic Polyolefin (TPO):  A single-ply roofing membrane that is one of the fastest growing commercial roofing systems on the market. TPO roofing systems are made up of a single layer of synthetics and reinforcing scrim that can be used to cover flat roofs.

  • Turtle Vent: Turtle vents are non-mechanical curved vents (yep, like a turtle shell) that allow hot air to escape the attic space. 

  • Underlayment: An asphalt-saturated felt or other sheet material (may be adhering) installed between the roof deck and the roof system, usually used in a slope roof construction. Underlayment is primarily used to separate the roof from the roof deck, to shed water, and to provide secondary weather protection for the roof area of the building.

  • Underwriters Laboratories, Inc. (UL): An organization that tests, rates and classifies assemblies for their resistance to: fire, impact, leakage, corrosion of metal, and wind uplift.

  • Wicking: The ability of a liquid to flow in narrow spaces

  • Wind Load: Force exerted by the wind on a structure or part of a structure.

  • Wind Turbine: Wind turbines are a type of attic exhaust vent that make up half of a balanced attic ventilation system for each roof. Intake vents make up the other half of the system.

  • Wind Uplift: The force caused by the deflection of wind at roof edges, roof peaks or, causing a drop in air pressure immediately above the roof surface. This is then transmitted to the roof surface. Uplift may also occur because of the air pressure underneath the membrane and roof edges, where it can cause the membrane to balloon and pull away from the deck.