Aggregate Stone, slag or river rock that comes in a variety of sizes. Used as ballast and / or UV protection for certain roof systems, BUR, EPDM etc. Alligatoring A characteristic in asphalt which occurs during aging. Exposed asphalt inherently over time loses volatile oils, in conjuction with oxidation caused by UV exposure (solar radiation) creates a pattern of cracks. These cracks resemble alligator hide. Apron Flashing A term used for a flashing located at the juncture of the top of a sloped roof and a vertical wall, chimney or steeper sloped roof. Architectural Shingle A laminated asphalt shingle that provides a dimensional appearance. Asphalt a dark bituminous substance that is found in natural beds and is also obtained as a residue in petroleum refining and that consists chiefly of hydrocarbons. Asphalt is used in many different roofing products, including but not limited to, shingles, underlayments, emulsions etc. Asphalt Shingle A shingle manufactured by coating a reinforcing material (felt or fibrous glass mat) with asphalt and having mineral granules on the side exposed to the weather (see shingle) ASTM American Society for Testing and Materials Ballast Various materials used to protect roof systems from UV rays, or to prevent blow off of systems which are not fully adhered. River rock, brick, pavers etc. Back Nailing Installation of nails in roof felts (to the deck) under the overlaps along with hot mopping to precent slippage during process. Base Sheet (Ply) An asphalt saturated or coated felt, installed as the first layer (ply) with 4" laps in a built up roof (BUR) system. Base Flashing A portion of the flashing attached to or resting on the deck used to direct the flow of water onto the roof covering Bitumen Bitumens are mixtures of hydrocarbons of natural or pyrogeneous origin; or combinations of both, frequently accompanied by their non metallic derivatives, which may be gaseous, liquid, or solid, and which are completely soluble in carbon disulfide. In the roofing industry the word covers both asphalt and coal tar pitch Blister / Blistering An enclosed bubble (under the surface). Can be caused by different reasons, for example, expansion of trapped air and water - vapour or moisture or other gases. Some blisters will expand during rising outside temperatures, this also causes the plies of roofing material to seperate from each other or from the deck. Blueberry blisters are smaller in size and are more common on unprotected roof systems (smooth modified or BUR without coating or aggregate) Blocking (aka Racking) A method of applying shingles in vertical rows from the eave to the ridge, rather than horizontally from rake to opposing rake. This is not a recommended method of installation, some shingle manufacturers will not warranty this. BUR / Built Up Roof Layers, or plies of roofing felt, bonded together with hot bitumen (see bitumen and asphalt), typically finished with a flood coat of hot bitumen and a protective coating or aggregate (rock etc) Cant Strip A bevelled material used at the intersection of a roof deck with vertical structural detail (parapet wall). Used to support roofing membrane used to form a base wall flashing in order to prevent breakage of materal (felts, modified, membrane etc). Made of various materials including bevelled wood, insulation, grout or concrete etc. Cap Sheet A granulated surface bitumen material commonly used as the top ply of a built up roof system (BUR). Use of aggregate for UV protection is not necessary when a cap sheet is installed. Cladding Material used as the exterior wall enclosure of a building Class "A" Refers to the highest of fire- resistant ratings in regards to roofing materials per ASTM E-108. A Class "A" rating indicates the material is able to withstand severe exposure to fire originating from outside the building in which the material is installed and will not support a flame on it's own. Closed Cut Valley A method of valley application in which shingles from one side of the valley extedn across the valley while shingles from the other side are trimmed back either in the middle of the valley or off center. Coal Tar A dark brown to black colored, semi-solid hydrocarbon produced by the distillation of coal. Coal tar pitch is further refined to conform to certain roofing grade specifications; Coal Tar Pitch: A coal tar used as the waterproofing agent in dead-level or low-slope built up roof membranes and membrane waterproffing systems, conforming to ASTM Specification D 450 Type I Coal tar waterproofing pitch: A coal tar used as the dampproofing or waterproofing agent in below-grade structures, conforming to ASTM Specification D 450 Type II Coal Tar Bitumen: A proprietary trade name for TypeIII coal tar used as the dampproofing or waterproofing agent in dead-level or low slope built up roof membranes and mambrane waterproofing systems, conforming to ASTM D 450 Type III Cold Roof Assembly a rof assembly in which the insulation is located below the deck, and not typically in contact with the deck, allowing for ventilation space. The temperature of the roof assembly remains close to the outside air temperature. Composition Shingle An asphalt shingle roof, non specific to the design. (see further shingle definitions) Composite board roof insulation Rigid board insulation generally comprised of perlite or wood fiberboard factory bonded to polyisocyanurate or polystyrene. Compounded Thermoplastics A category of roofing membranes made by blending thermoplastic resins with plasticizers, various modifiers, stabilizers, flame retardants, UV absorbers, fungicides and other proprietary substances alloyed with proprietary organic polymers Condense To make denser or more compact, as when a material (water vapor etc) changes from it's gas phase to it's liquid phase Condensation The conversion of water vapor or other gas to liquid phase as the temperature drops; the act or process of condensing Coping The covering piece on top of a wall exposed to the weather, usually made of metal, masonry, or stone and sloped to carry off water Copolymer The product of polymerization of two or more substances, as two different isomers, together Core Sample (1) a smaple taken from a low-slope roof system for the purpose of obtaining information about it's construction. Typically core sample analysis can reveal the type of materials used, the number of plies, thiickness and condition of insulation (if present) and the type of deck material used as the substrate for the system. (2) in regards to an SPF roof system, core samples are used to obtain both quantitative and qualitative information (thickness of the foam, thicness and adhesion of the coationg, thickness of installation passes, and adheasion between each pass and to the substrate. Cornice The decorative horizontal molding or projected roof overhang Counter batten Vertical wood strips installed ona sloped roofs over which horizontal batens are secured. The primary roof covering is attached or secured to these horizontal battens (tile, slate, aluminum shingles etc) Counterflashing Metal or elastomeric sheeting, secured on or into a way, curb, pipe, rooftop unit or other surface, to cover and protect the upper edge of base flashing and it's fasteners. Course A term used for a row of roofing material , and/or one layer of a series materials. CPA Copolymer alloy Cricket A relatively small area of a roof constructed to divert water from a horizontal intersection of the roof with a chimney, wall, expansion joint or other projection. Curb (curbing) A raised member used to support roof penetration fixtures, skylights, mechanical equipment (HVAC) hatches etc, above the roof surface, also a low raised roof perimeter. Cure A process whereby a material is caused to form permanent molecular linkages by exposure to chemicals, heat, pressure, weathering. Cure time is the time required for a material to reach it's resiliant long term characteristics. Cured, is also used in reference to the time frame a material has been exposed to weather, and will eventually lose it's resiliant qualities. Dead level Absolutely no slope Deck A structural component of a roof. The deck supports the design, dead, and live loads, including the weight of the roof system, and additional live loads (ie snow etc.) as set forth (requred by) in building codes. The seck also provides the substrate to which the roofing or waterproofing system is applied to the structural surface of a building. Decks can be non combustible, metal, concrete, gypsum, or combustible, wood, plywood, osb etc. Degradation (degraded) A change in the chemical structure, physical properties or appearance of a material from natural or artificial exposure, (UV, moisture, heat, freezing, wind etc) Delamination Separation of the laminated layers of a component Dimensional Shingle a shingle that is textured, or laminate to produce a three dimensional effect **See architectural shingle** Dormer A structural projection from a sloping roof, typically housing a window, or a ventilation fixture Downspout A vertical pipe, or conduit used to facilitate runoff water from a scupper, or gutter of a building to a lower roof level, to the ground, or a storm drain system. Drip Edge Metal flashing, or other overhanging component with an outward projecting lower edge, used to control the direction of dripping water and help protect underlying building components (fascia etc) Eave The lower edge of sloped roof, extending past the wall. Eave Vent Protected openings along roof perimeter (edge) used as the intake part of a ventilation systems, to disapate heat and moisture. Elasticity The flexibility property of returning to an initial for or state following deformation (streching, pulling, compression etc) Elastomeric Coating A coating that is capable of being streched at least twice it's orginal length (100% elongation) and returning to it's original dimensions when pressure is released. Elongation The extension of a material (streching) beyond it's original state. Emulsion A mixture of bitumen (asphalt) and water, with uniform dispersion of the bitumen or water glbules, usually stabilized by an emulsifying agent or system. End Lap The distance of the overlap where one ply, or piece extends beyond the end of the immediatly adjacent underlying ply / piece. EPDM (Ethylene Propylene Diene Monomer) A material used for low slope roof installations. Typically black in color, although some manufacturers have introduced white sheets. Epoxy A class of synthetic, thermosetting resins that produce though, hard, chemical-resistant coatings and adhesives. Ethylene Interpolymers (EIP) Thermoplastic compounds generally based on PVC polymers from which single ply roofing membranes can be formulated Exhaust ventilation Aire that is vented, / exhasted from the roof cavity or attic space. Typically through vents installed near the ridge of a sloped roof. Expansion Joint A structural separation between two building elements that allows free movement between the elements without damage to the roofing system. Eyebrow A dormer, typically small, whose roof line is arched, (curved) resembling the arch of an eyebrow. Fabric A woven cloth or material of organic or inorganic filaments, threads, or yarns used for reinforcement in certain membranes, flashings, and roof systems. Fascia On a sloped roof, the fasica board is nailed to the end of the rafters, sometimes supporting a gutter, on low sloped roofs it is typically a border around the perimeter. Felt A flexible sheet of interlocking fibers with a binder, or through moisture or heat process. Typically manufactured from wood pulp and vegetable fibers (organic) glass fibers, or polyester fibers. Used as an underlayment in some roof systems (shingle systems for example) Field Seam A splice or seam made in the field, where overlapping sheets are joined together using sealing / joining method particular to the roof system. Fishmouth A half cylindrical shaped opening or void in a lapped edge or seam. Typically caused by wrinkling or shifting of ply sheets during installation. Shingle fishmouths occur at the cut edge. Flashing components used to weatherproof or seal roof system edges at perimeters, penetrations, walls, expansion joints, drains and other areas where the roofing material is interrupted or ends. Fleece Mats or felts composed of fibers, sometimes used as a membrane backer for fully adhered installations. Flood Coat Surfacing layer of bitumen (asphalt) on a built up roof installation. Gable The vertical triangular portion of the end of a building with a double sloped roof Galvanize To coat steel or iron with zinc for corrosion resistance Guage A metal thickness measurement. Granule Opaque, natural or synthetically colored aggregate commonly used to surface roofing materials, shingles cap sheets, etc. Gravel Stop A flanged device typically metal, designed to prevent loose gravel (aggregate) from washing off the roof. Also serves as a continuous finished edge. Gussett Typically used at the bottom of a valley, a flat metal piece, wider thant the valley to help prevent debris build up at the base of the valley. Hand Tabbing Spot applying adhesive (asphalt based) to underside of shingles for extra securement and wind resistance. Heat Seaming AKA heat welding, the process of joining thermo plastic membranes by heating and then applying pressure to join materials together. Hip The inclined external angle formed by the intersection of two sloping roof planes. HVAC Heating, Ventilating and air conditioning equipment. Ice Dam Ice formed at the transition from a warm to a cold roof surface. Typically formed at the over hang (eave). Snow melts down from the warm area of the roof, over attic space, to the eave where the temperature is the same as the ambiant temperature, where it freezes. Ice and water will then back up under roofing materials and can result in a leak. Impact Resistance Resistance to fracture under sudden application of force. For example, shingle manufacturers are producing impact resistant shingles for hail prone areas. Impregnate In regards to roofing materials; completely surround fibers in a felt or mat with bitumen. Spaces between the fibers are partially or completely filled without a continuous coating of bitumen on the surface. Infrared Thermography The process of displaying variations of apparent temperatures over the surface of a roof by measuring the viariations in infrared radiance. Inorganic composed of materials other than hydrocarbons and their derivatives, matter that is not of plant or organic origin. Insulation Materials designed to reduce the flow of heat, either entering or exiting a building. Intake Ventilation Fresh air drawn into a passive ventilation system through vents typically installed in the soffit or eave of a roof. Interlayment a felt, metal, or membrane sheet material used between courses of steep-slope roofing to improve the weather and water shedding characteristics of the primary roof materials in times of wind driven precipitation. This method is typically used in wood shake installations. Interlocking Shingles These are individual shingles that mechanically attach to each other. This provides additional wind resistance as they do not rely soley on sealing strips. Isolation Sheet Refer to Slip Sheet Joist Timbers, metal, or wood beams that are arranged parallel to each other, spanning from wall to wall, supporting a floor, ceiling or the roof of a building / structure. Laminate To join layers of materials together. The process of joing layers of materials together utilizing ahesive / adhesion. Laminated Shingles Refer to Dimensional or Archtectural shingles Liquid Applied The application of bitumous cements, adhesives, coatings, applied at ambient or slightly above ambien temperatures (cold applied) Live Loads Temporary in nature loads that the roof structure must be designed to support as set forth in govt building codes. Generally dynamic or environmental (installation equipment, snow, rain, ice, service personel etc) Loose Laid Referring to a ballasted roof system whereas membrane is attached to the substrate only at the edges and the penetrations of the roof. Ballast is required as there are no field attachments along the roof with the exception of penetrations. Low Slope Roof A roof with a pitch (slope) lower or lesser than 3:12 (14 degrees). Typically these roofs have membrane (single ply, EPDM, modified bitumen) roof systems installed as shingles are not meant to be waterproof, but to shed water. Low temperature flexibility The ability of roofing material to flex, resist cracking when subjected to low temperatures. Particularly important on roofs where there may be anticipated foot traffic during winter months for maintenance. Mansard A decorative addition, steep slope usually with shingles or metal on the perimeter of a building. A mansard roof is this portion of a roof, which terminates into a flat roof at it's highest point. Mastic An adhesive material (cementing agent) used to facilitate holding waterprofing membrane in place on a roof surface. Mat Thin layer of woven, knitted, or non woven fiber used as a reinforcement in roofing materials. (shingles, membranes) MSDS (Material Safety Data Sheets A written description of chemicals and other pertinent data in a roofing material. Including safe handling and emergency procedures. It is the responsibility of the manufacturer to produce an MSDS to comply with OSHA regulations. Mechanically Fastened Referring to membrane (single ply) installations, describing the process of attaching the membrane at strategic points to the substrate (screws and plates etc) Membrane A flexible / pliable roofing material which excludes water (waterproofing sheet) Metal Roof Panel an interlocking metal sheet, with an installed exposure of approx. 3 square feet. Metal Roof Shingle Interlocking metal component, with an installed exposure of less than 3 feet. Mil A unit of measurement. One mil is equal to .001 inches, 25.4 micrometers. Used to indicate the thickness of a roofing material, typically membrane. Mildew Growth produced on organic matter or living plants by fungi. Millimeter A unit of measurement, equalling .03937 inches. Mineral Surfaced Roofing Roofing material with a surface (top) of granules (embedded). Mineral surfaced sheet, commonly referred to as "rolled roofing", a class B material typically used on out buildings. Model Codes Commonly referred to as "building codes", are standards or codes established to provide uniformity in regulations in regards to construction. These codes are set forth by local govt entities. Modified Bitumen A roofing material used on low slope roofs. a bitumen modified by adding one or more polymers (atactic polypropylene, butadiene styrene etc.). Sheet forms are typically reinforced with various types of mats or films, also surfaced with films (smooth modified) or mineral granules (granulated modified) Moisture Relief Vent AKA Anti condensation vent, a device installed through roofing membrane to vent moisture vapor pressure from within the system. Moisture Scan A process utilizing a device (infrared, capacitance etc) to detect the presence of moisture within a roofing system. Monolithic / Monoform A roofing system formed from or comprised of a single material, hence seamless. Monomer Low molecular weight substance, consisting of molecules capable of reacting with like or unlike molecules to form a polymer. Mopping Application of a hot bitumen with a mop applicator to the substrate or plies of membrane Nailer Lumber and or plywood material (incl osb) secured to the deck, or walls, that provides a receiving medium for the fasteners used to mechanically attach single ply membranes, or flashing. Net Free Vent Area Area open to unrestricted air flow. Commonly used as a measuring unit of sorts, to measure vent performance. (eg; area of the opening of vent, minus the area displaced by the screening material) Night Seal / Night Tie In The method of temporarily sealing an existing membrane edge to the newly installed membrane edge, while roof installation is underway, but halted by nightfall. This method is used to protect structure from possible water until roof installation can resume. Non Traffic Bearing A roof system that will not withstand foot traffic without reinforcement / protection (walk tread etc) Nonwoven Fabric A roofing related textile structure processed by bonding or interlocking fibers. This is accomplished by use of chemicals, thermal, solvent or mechanical processes. NRCA National Roofing Contractors Association Open Valley A type of material installation in the valley (steep slope roofs) where both sides of the valley are trimmed, and metal installed (exposed) in the valley Organic Composed of hydrocarbons or derivatives, or of plant or animal design. Overflow Drainage A component in a roof drainage system. This component is to safeguard the roof structure in the event primary drains are blocked, or partially blocked, thus there is a large collection of water on the roof. (scuppers, overflow interior drains) Parapet Wall The portion of the perimeter wall that extends above the roof level. Pass Refers to one layer of roofing material applied, typically in regards to spray materials. (SPF, emulsion etc) Pedestal A base, or support for roof top components, HVAC units, pipes, pavers etc. Penetration Any fixture construction that passes through the roof surface (HVAC, pipes, conduits etc) Perlite Aggregate used in insulating concrete and preformed insulation boards Pipe Boot Prefabricated flashing unit used to flash around pipe penetrations. Pitch Pan / Pitch Container Flanged open bottomed fixture made of sheet metal (or other) placed around a roof penetration, filled with sealants to seal the area around penetrations. Plasticizer Material incorporated (mixed) in a material increasing it's ease of flexibility or warkability. Pliability Property of a roofing material to be flexible or moldable. Ply A layer of felt or sheet in a BUR (built up roof) system. Polymer Macromolecular material formed by chemical combination of monomers Polyvinyl Chloride / PVC Synthetic Thermoplastic polymer processed from vinylchloride. The flexibility or rigidity of PVC is contingent upon the use of plasticizers, stabilzers, fillers and other modifiers. EG, used in pipes for plumbing (rigid form) single ply membranes (flexible form) Pond (ponding) On a roof surface, an area that is incompletely drained. Primer Solvent based, liquid applied bitumen, typically used to approve adhesion of bitumen based roofing materials, applied to the substrate. PVC Polyvinyl Cloride R-Value A term used to describe the thermal resistance of insulation, see THERMAL resistance. Racking A method of asphalt shingle installation where courses are aplied vertically up the roof. This is not a recommended installation method. Rafter A structural component installed from ridge (high point) to eave, designed to support the roof deck, roof system and live loads. Rake The sloped edge of a roof, directional of rafter. Rake Starter Bleeder Strip - Starter Strip. Used along the rake edges in an asphalt shingle installation. Re-cover Installation of new roofing materials over existing roof system. Reflectivity The ability of a roofing material to reflect light instead of absorbing and the heat. Release Tape / Strip Plastic or paper film or strip applied to self sealing shingles to prevent them from sticking toether in the packaging. This strip need NOT be removed during installation. Ridge Highest point of the roof, where two slopes come together. Ridge Cap The roofing material specifically purposed / manufactured for installation on the ridge. Ridge Vent Contiuous ventilation along the ridge of the roof utilizing specifically manufactured vent components. Roof Cement See asphalt roof cement. Roof Covering The outer most exterior layer of roof assembly. Roof Jack A bracket used to support toe boards on sloped roofs, these are for saftey and convenience during roof installation. Roof Slope (pitch) The rate of vertical rise to horizontal length. 4:12 = four inch vertical rise per 12 inch horizontal lentch Roof System All components included in the installation of a roof. Rubber Quite possibly the most mis-used term when referring to low slope or flat roof materials. Run The horizontal dimension of a roof slope. Saddle See Cricket Saturated Felt A felt material that has been immersed in hot asphalt (bitumen). The materail remains porous, used as underlayment for various roof systems. SBS Styrene Butadien Styrene. Scrim A woven or nonwoven fabric of continuous strands of material. This is used as a reinforcement for strengthening membranes. Scupper A secondary (back up) drainaige device, through a wall or parapet wall. Self Adhering Membrane A roofing membrane manufactured to self adhere to the substrate and underlying material by removal of a film or paper. Shingle A small unit designed for installation with like units, overlapping rows, for installation on slopedroofs. Typically steeper sloped than 3:12. Ther term "Shingle" also refers to the act of installing shingles Shrinkage A decrease in one or more dimensions of an object or material. In regards to roofing, some materials will, over time, shrink, and begin pulling away from parapet walls / perimeters. Single Ply Membrane Roofing Membranes that are field applied using just one layer of single ply. Often thermoset or thermoplastic. Skirt Flashing Metal counterflashing used under a mechanical unit, or skylight. Used to cover an protect the upper edege of a base flashing enad it's fasteners. Slate A hard brittle rock consisting mainly of clay minerals. Used on steep sloped roofs. Slip Sheet A sheet material (kraft paper, plyester scrim, polyethylene etc) placed betweent to components of a roof system. It's purpose is to ensure no adhesion occures between them and to protect one or more component. Snow Guard A series of devices attached to a roof in a pattern used to prevent snow sliding from the roof in a sheet onto the ground. These are used on steep sloped roofs and metal roofs. Snow Load The live load due to the weight of snow (see live load) Soffit The undersurface of any exterior overhanging section of a roof eave. Soffit Vent Intake vents installed unobstructed at the eave to facilitate circulation of air along the underside of decking to exhaust vents located at the ridge or near the ridge. SPF Spray Polyurethate Foam, formed by spraying two components "A" and "B" that forms a fully adhered insulating membrane. SPF Compound A term used to describe the raw materials used to make polyurethane foam (Isocynate and resin) Square A unit of measurement used for roof areas. One square = 100 square feet. Standing Seam A type of seam between adjacent sheets of metal material which are manipulated and then interlocked. Starter Course The first course of roofing material, installed at the lower most edge. Steep Slope Roof A roof with a pitch, or slope greater than 3:12 - 14 degrees Step Flashing Individual pieces of sheet metal material used to flash around chimneys, dormers, walls. Strapping A method of installing roof felts parallel with the slope of the roof. Surfacing The top layer of a roof covering specifically in place to protect the underlying material from direct exposure to UV or weather (granules etc) Tar A brown or black bituminous material liquid or semi solid in consistency. Tear Strength the maximum force require to tear a roofing material Tensile Strength The strenth of a material under tension as distinct from torsion, compression or shear. Thermal Expansion The increase in the dimension or volume of a body due to temperature variations. Thermal Insulation A material used to reduce the flow of heat. Thermoplastic A material that softens when heated and hardens when cooled, used in roofing single ply membranes. Thermoplastic Olefin Membrane (TPO) A blend of polypropylene and ethylene propylene plymers, flame retardants and other proprietary substanes for desired physical properties. TPO may or may not be reinforced. Tie In The transition from one roof system to another type roof system. Typically where a steep sloped roof, terminates and joins with a low slope roof, the tie in is the junction between the two roofing materials. Tongue and Groove One of the oldest types of wood used as roof decking. The sides are convex and concave, joining and aligning each other to form deck. Traffic Bearing In roofing, a membrane or area of roofing system forumlated to withstand foot traffic. (Walk Tread for maintenance workers / HVAC) UL Underwriters Laboratories Inc. A testing facility, which certifies roofing and other materials have met certain criteria. Ultraviolet / UV Invisible light radiation, adjacent ot the violet end of the visible spectrum with wavelengths from about 200 to 400 nanometres Underlayment An asphalt saturated felt, or other sheet type material installed between the roof deck and other roofing materials. Underlayments are also a second line of defense in shedding water on steep sloped roofs. Valley The area (internal angle) formed by the intersection of two sloping roof planes.