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Dictionary of Roofing Terms
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T Tab: The portion of an asphalt shingle that is outlined by the cutouts. Tapered Edge Strip: Tapered insulation strip used to ease transitions from one substrate elevation to another and to provide slope along roof perimeters. Tape: See Joint Tape and Splice Tape. 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. Tar Boil: A small bubble found in the flood coat of an aggregate-surfaced built-up roof; usually the result of trapped moisture vapour. Tar Boils are also known as blueberries or blackberries. Tear-Off: To remove a roof system down to the structural substrate. Tear Resistance: A material’s ability to withstand tearing. The test is performed by placing stress on an area of the material where a flaw is located. Tear Resistance is expressed in psi per inch width or kilo-newton per meter width. Tear Strength: The strength necessary to tear a material. Tensile Strength: The amount of longitudinal pulling stress that a material can withstand before being pulled apart. Tension leveling:
Process that
takes the
distortion out
of the metal
prior to
rollforming, to Termination: The sealed edges of a roof membrane. Termination Bar (Term.’ 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 semifired 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 Barrier: Material used in conjunction with polyurethane foam that is designed to inhibit the rise in temperature of the foam during a fire in order to delay the foam’s involvement in the fire. Time ratings for thermal barriers should exceed 15 minutes. Thermal Conductance (C): A constant, equal to a material’s k-value (Thermal Conductivity) divided by the material’s thickness in inches; used often for materials of composite construction such as insulation. For more information,See Table 1. Thermal Conductivity (k): The heat energy that will be transmitted by conduction through 1 square foot of 1inch thick homogeneous material in 1 hour when there is a difference of 1 degree Fahrenheit perpendicularly across the two surfaces of the material. The higher the k-value, the lower the R-value. Materials with high k-values are good heat conductors, and conversely. For more information, see Table 1. Thermal Insulation: A material used to reduce heat flow. Thermal Movement: Movement of a material resulting from temperature changes. Thermal Resistance (R): The measure of a material’s ability to resist heat flow. The formula for Thermal Resistance is R = L / k where (L) is the material’s thickness and (k) is the material’s Thermal Conductivity constant. The higher a material’s R-value, the better it insulates, and conversely. For more information, See Table 1 Thermal Shock: The damage to a roof resulting from expansion and contraction which are the result of sudden extreme temperature changes. Thermal Shock often occurs when a cold rain shower suddenly cools a roof during a hot day. Thermal Stress: Stress to a roof system or component caused by expansion and / or contraction from temperature change. Thermoplastic: (1) adjective Becoming soft when heated and hard when cooled. (2) Noun a thermoplastic resin, such as polystyrene or polyethylene. Thermoset: A material that cannot be reshaped or formed by heating. EPDM and Butyl are thermosets. Thinners: Liquids that are used to reduce a material’s viscosity when mixed but that evaporates during cure. Thixotropy: Property of certain materials which liquefy when they are subjected to vibratory forces such as simple stirring or shaking and then solidify when left standing. Throat: (1) The cutout of a shingle. (2) The narrowing passage located between a fireplace and smoke chamber or flue. 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. Can be temporary (see Night Seal) or permanent. TIMA: Thermal Insulation Manufacturers Association Toggle Bolt: A bolt with a separate toggle end that can be flattened to fit through a pre-drilled hole and that springs outward to provide securement when the bolt is tightened. Tongue and Groove: Premanufactured materials with a convex "tongue" on one side and a concave "groove" on the other so that pieces of material can be joined together by placing the tongue of one piece into the groove of an adjacent piece so that the pieces fit more securely together. Torque: Force applied to an object, particularly, to screw a mechanical fastener into a roof deck or substrate. TPA: Tri-Polymer Alloy. Traffic: Any rooftop activity that can potentially damage the roof surface. 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. Treebark Surface Texture: An SPF surface deemed unacceptable for coating. This surface texture has deep valleys and is similar in appearance to rough tree bark. Tuck Pointing: To remove old and deteriorated mortar from between masonry blocks and replace it with new mortar. U U-Value: The overall coefficient of heat transfer of an assembly measured in BTUs per square foot, per degrees Fahrenheit difference in temperature per hour. UBC: Uniform Building Code. UL: Underwriters Laboratories, Inc. UL Label: A label that has been stamped on certain materials by authority of Underwriters Laboratories, Inc. indicating that the material has met certain performance criteria. 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 (15#) or thirty (30#) pound organic felt but can also be self-adhering such as an ice and water protection membrane. Underwriters Laboratories (UL): A non-profit agency which functions as the testing arm of the National Board of Fire Underwriters. It maintains laboratories for the examination and testing of various devices, systems, and materials to determine their safety against the hazards of fire, wind, and accidents. Uplift: See Wind Uplift. Upside Down Roof: See Protected Membrane Roof. V Valley: The internal intersection of two sloping roof planes that runs from the eaves to the ridge. This intersection collects the most water run-off. See Open Valley, Closed-Cut Valley, and Woven Valley. (See Fig 1) Vapour Migration: The natural movement of water vapour from regions of higher vapour pressure to regions of lower vapour pressure. Vapour Pressure: The pressure at which a liquid and its vapour are in equilibrium at a definite temperature. Vapour Retarder: A material used to restrict the passage of water vapour through a roof assembly. Veneer: Any of the thin layers of wood glued together to make plywood. Vent: An opening or device used to permit air or vapours to exit an enclosed structure. Ventilation Short Circuit: The disruption of airflow in an intake-exhaust ventilation system. For instance, if vents such as turbine vents or gable vents are placed in between the intake vents and exhaust vents (such as soffit and ridge vents) then the draw created by the Stack Effect will be disrupted and the ventilation system will be much less effective. Ventilator: A device that circulates fresh air and expels stale air. Verge of Popcorn Texture: A rough surface texture of Sprayed Polyurethane Foam generally considered unsuitable to receive a base coating. Nodules on this surface are larger than the valleys and an additional 50% or more of coating material is necessary to properly cover and protect the surface. Photos? Vermiculite: One off a group of micaceous hydrated silicate minerals related to the chlorites and used in lightweight insulating concrete. Viscosity: The resistance of a material to heat flow. Viscous: Having a fairly high resistance to heat flow. Void: An open space or a break in continuity; a gap. Volatile: That which readily vaporizes; evaporates quickly. Vulcanise: To improve the strength, resiliency, and freedom from stickiness and odour of rubber, for example, by combining with sulphur or other additives in the presence of heat and pressure. W Wash
coat:
(Metal
sheeting) A
coating applied
to the back or
unexposed side
of the strip.
Its purpose is
to protect Water Absorption: The increase in weight of a test specimen expressed as a percentage of its dry weight after being immersed in water for a specified time at a given temperature. Water Cure: To control the rate of cure of materials such as concrete by spraying a fine mist of water on the surface. Water Cut-off: See Night Tie-Off. Water Guard: A turned up edge on valley metal or continuous wall flashing; used to prevent water migration under the roof system. Water Stop: Material placed over a joint and used to prevent water entry. Waterproof: Being resistant to moisture infiltration. Waterproofing: The treatment of a surface or structure in order to prevent the passage of water under hydrostatic pressure. Water Trough: The area in a valley where water runs. Usually referred to with open valley configurations. Weather: To undergo degradation in quality and appearance which is caused by exposure to the sun, wind, rain, etc. Weep Holes: Small holes used to permit moisture to drain that has gathered inside a building component. Weld: To join multiple metal or PVC components together by heat fusion. Wet Bulb Temperature: Air temperature in ° F as measured by a thermometer with a bulb covered by a damp wick. Wet Film Thickness: The thickness of an uncured material such as a coating. Wick: To convey liquid by capillary action. 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. Wind Load: The force that wind puts on structures. Wind Uplift: (1) The upward displacement of a section of a roof system or component caused by movement of air from a location of higher air pressure, such as inside a building, to an area of lower air pressure, such as the surface of a roof during a windy day. Strong wind across the surface of a roof, especially at corners and along perimeters, creates low air pressure above the surface of the roof. Nature will automatically try to compensate for this by moving air from an area of higher pressure such as inside a building. If all penetrations and perimeters are not properly sealed, then "blow-off" can occur. (2) Displacement or blow-off of shingles or other roofing caused by the wind. Windward: Facing into the wind. 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. Z Z Bar or Z Section: A piece of steel formed in the shape of a "Z." 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. Atomic number 30; atomic weight 65.37; melting point 419.4 °C; boiling point 907 °C; specific gravity 7.133 (25 °C); valence 2.
Although these pages are checked regularly and every care is taken with the information within. Delston can not accept any responsibility or liability for information or results displayed within due to third party interference. Author Myrddin
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