Roofing Definitions

Sloped Roofs

Common roofing terminology

• Absorption Value - the measure of a materials’ ability to accept quantities (such as moisture) or gas.

• Aggregate – a mixture of sand, stone, and other fragmented particles; a major component of concrete.

• Alligatoring – a condition resulting from drying and deteriorating roof surface, producing a pattern of cracks similar to an alligator’s hide.

• Allowance Factor – a term used in estimating the amount of roofing material needed for a job which accounts for over-cutting and lapping.

• Apron Flashing – flashing located at the junction of the top of a sloped roof and a vertical wall, chimney, or steeper-sloped roof.

• Asbestos – a group of natural, fibrous impure silicate materials.

• Asphalt – a dark brown to black material containing mainly bitumen found in a natural state.

• Asphalt Emulsion – a mixture of asphalt particles and an emulsifying agent such as bentonite clay and water.

• Asphalt Flat Roof Repair - fixing a dark to black material on a low-sloped roofing containing mainly bitumen in the mix.

• Asphalt Roof Repair - general fix of a dark to black material on a low-sloped roofing containing mainly bitumen in the mix.

• Asphalt Roof Replacement - the complete removal and reinstallation of a new fix of a dark to black material on a low-sloped roofing containing mainly bitumen in the mix.

• Asphalt Roofing Contractors - the company that provides the series of maintaining, repairing, or replacement of a dark to black material on a low-sloped roofing containing mainly bitumen in the mix.

• Asphalt Shingle Repair - repair roofing tiles on a dark to black material on a low-sloped roofing containing mainly bitumen in the mix.

• Ballast – aggregate materials installed on some low-slope roofs to provide weather protection and fire resistance.

• Base Sheet – a saturated, impregnated, or coated felt that is placed as the first and heaviest membrane installed in a low-slope roofing system.

• Batten – a strip of wood set in or over the structural deck, used to elevate and/or attach a primary roof covering system. 

• Asphalt Shingle Roof Leak Repair – repairing a shingle roof with water leaks on the membrane roof.

• Best Commercial Roofing Companies -  A company that specializes in maintaining, repairing and replacing roofing systems.

• Best Flat Roof Repair - A flat roofing repair that satisfies the highest industry standards.

• Best Roof Repair - A roofing repair that satisfies the highest industry standards.

• Best Roofers - Roofing service individuals that exceed in the industry.

• Roofing Companies - Roofing companies that exceed in the industry.

• Bitumen – a black or dark-colored cement based-substance composed of high molecular-weight hydrocarbons and found in asphalts and tars.

• Flat Roof Repair - Fixing a low-sloped roof that is made of black or dark-colored cement-based substances composed of high molecular weight hydrocarbons and found in asphalts and tars.

• Bitumen Roof Repair: Fixing a roof that is made of black or dark-colored cement-based substances composed of high molecular weight hydrocarbons and found in asphalts and tars.

• Blister – a raised portion of a roofing membrane resulting from local internal pressure, such an enclosed pocket of air, trapped between impermeable layers of felt or membrane or between the membrane and substrate.  Also refers to surface swelling in roofing material such as asphalt shingles.

• Built Up Roof Repair - The fixing of a built-up roof (BUR) which is a type of low-slope membrane roofing made up of asphalts or coal tar saturated felts, coated felt, fabric or mats within layers of asphalt or pitched bitumen.

• Built-up Roof (BUR) – a type of low-slope membrane roofing made up of asphalt or coal tar saturated felt, coated felts, fabrics or mats within layers of asphalt or pitch bitumen.

• Bundle – a package of singles, that is three bundles per square and 27 shingles per bundle.

• Butt Edge – the lower edge of the shingle tabs.

• Cant Strip – a 45 degree angle of ridge block insulation (i.e. or other material) used to transition the horizontal roofing membrane from horizontal to vertical and relieve deterioration stresses.

• Capillary Action – the act that causes siphoning of liquids into voids by surface tension when in contact with two adjacent surfaces such as panels side-laps roofing membrane.

• Cedar Roof Company: A contractor that specializes in the maintenance, repair, and replacement of cedar roofing systems.

• Cedar Roof: Cedar shake roofs are made of wooden shingles produced from split logs. Aesthetically appealing look because the thickness and length of each shingle can vary by the natural wood growth.

• Cedar Shake Roof Repair: Fixing a damaged cedar roof.

• Ceiling Joist – one of a series of parallel framing members used to support ceiling loads.

• Certified Roofers:  A roofing individual that has passed the manufacturer’s certification process. 

• Certified Roofing Company: A company employing a roofing contractor that has passed the manufacturer’s certification process. 

• Chalk Line – a made by snapping a taut string or cord dusted with chalk use for alignment.

• Closed-cut Valley - a valley in which shingles from one side of the valley extends across the valley, while shingles from the other side are trimmed back approximately two inches from the valley centerline.

• Coal-tar Pitch – a bitumen utilized as a waterproofing agent used in low-slope BUR membranes roofing systems.

• Commercial Roof Replacement - the maintenance, repair, and replacement of commerce buildings. 

• Condensation – conversion of water vapor or other gas into a liquid phase as the temperature drip or atmospheric pressure rises.

• Conduction – direct contact transfer of heat energy through a material.

• Conductivity – rate at which heat is transmitted through a material.

• Contractors Roof Service -  A company that specializes in maintenance, repair, and replacement roofing membrane.

• Coping – the covering (cap) piece on top of a wall exposed to the weather as a parapet wall.  The top portion is cap with a coping stone, metal or other to protect it from moisture infiltration.

• Counter flashing – a formed metal sheet used to waterproof roofing penetrations.

• Crazing – cracking on the roofing surface of a material which can weaken and impair the material.

• Damp Proofing – treatment of a surface to resist the passage of water in the absence of hydrostatic pressure. 

• Deck – the structural part of a building’s roofing assembly. It lays above rafters and under the underlayment (i.e. the plywood boards).

• Dormer – opening in a sloped roofing system; framed to project outward and vertically to allow the installation a window assembly.

• Downspout – a pipe system, usually made of metal to carry and control the runoff of rainstorm water off the roof in a vertically downward manner and onto grade level.

• Drain – a round pipe outlet on the roofing system to collect and direct the flow of rainstorm runoff water from the roof.

• Drip Edge – a flat metal flashing with an outward projection at bottom edge to direct rainstorm water away from building surface.

• Eave – a projecting edge of a roof that extends beyond the supporting wall.

• Elastomer – any material that has the ability to return to its original shape after being repeatedly stretched to twice its size at ambient temperature.

• Emergency Roofing Repairs - The immediate action to correct a damaged roof.

• Equiviscous Temperature (EVT) – the temperature at which bitumen attains the proper viscosity (flow resistance) for BUR membrane application.

• Expansion Joint – a structure separation between two building elements that allow free movement between the elements without the damage to the roofing system.

• Fascia – horizontal boards attached to rafters or trusses at the lower ends of the eaves and along gables.

• Flat Roofing Replacement - Removal and installation of new low-steep roof.

• Felt – also known as “tar paper”, felt is an unwoven fabric produced by matting fibers under pressure.  Installed above the roofing deck for waterproofing.

• Fishmouth – a half-cylindrical or half-conical shaped opening or void in a lapped edge or seam, usually caused by wiring or shifting of ply sheets during installation. In shingles, it is a half-conical opening formatted at a cut edge.

• Gable – the end, upper, triangular area of a structure beneath the roof.

• Gable Roof – a roof containing sloping planes of the same pitch on each side of the ridge.

• Gutter – a shallow channel or conduit of metal or wood set below and along the downslope perimeter of a roof to catch and carry runoff water from the roof to the drain leaders or downspouts.

• Hail Damage Roof Repair: Ice balls the size of a marble or golf ball that fall from the clouds and damage the roofing system.

• Hip – the inclined external angle formed by meeting the two sloping sides of a roof.

• Hip Roof – a roof that rises by inclined planes of the same pitch from four sides of a building.  A hip roof contains no gables.

• Home Roofing Experts -  A roofing professional.

• Hydrostatic Pressure – the pressure exerted on a surface by a column of water.

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

• Insulation – any of a variety of roofing materials designed to reduce the flow of heat from or into a building.

• Interlayment – a layer of roof covering that is used in wood roof systems between each course of wood shakes.  Interlayment provides an extra layer of water shedding protection throughout the roof.

• Jack Rafter – a rafter that spans the distance from the wall plate to a hip, or from a valley to a ridge.

• Laminated – overland or coated with, such as oriented strand board (OSB) or plywood.

• Liquid-Applied – application of bituminous cements, adhesives, or coatings installed at ambient or slightly elevated temperatures.

• Live Loads – temporary loads that the roof structure must be designed to support (i.e ice, vehicles, people, snow, rainstorm water, wind, or temporary mechanical equipment). 

• Mastic – a pasty material used as a cement (as for setting tile); protecting coating, such as thermal insulation or waterproofing.

• Material Safety Data Sheet (MSDS) – a written description of the chemicals within a product, and pertinent other data including safe handling and emergency procedures. Occupational Safety and Health Administration (OSHA) requires the manufacturers to produce MSDS content to its employees.

• Metal Roof Replacement - The removal and installation of a new galvanized, aluminum, copper, or tin roofing system.

• Modified Bitumen – a bitumen, usually asphalt, with a polymer added to provide elastomeric properties and a fabric reinforcement to improve strength.

• Modified Bitumen Roof Repair - The fixing of a 2-ply bitumen system.

• Nesting – the installation of a new metal roof deck or metal roof panel without removing the existing metal deck or roof system.

• Neoprene – Synthetic rubber (polychloroprene) used in liquid or sheet-applied elastomeric roofing membranes or flashing.

• New Steel Roofers - Individuals that maintain, repair, or replace new galvanized, aluminum, copper, or tin roofing systems.

• NICA – National Insulation Contractors Association.

• Oil Canning – observable physical distortions in the flatness of metal; prevalent in light-gauge, cold-formed metal products.

• Open Valley – a method of valley construction in which the steep-slope roofing, that's covering materials on both sides, are trimmed along each side of the valley, exposing the metal valley flashing.

• Paper (Building Paper) – a general term for papers, such as felts and similar sheet materials used in building without referencing to their properties or use.

• Parapet Wall – the part of a perimeter wall extending above the roof and along the edges.

• Perlite – an amorphous volcanic glass that is typically formed by the hydration of obsidian. It is an industrial mineral and used for its light weight after processing.  Included in rigid insulation and used to make lightweight concrete.

• Permeability – a measure of the ease with which water penetrates or passes through a material.

• Perm Rating – the time rate of water vapor transmission between two specific surfaces, induced by the vapor pressure difference between them. The unit of measurement for permanence is ‘perm’ units.

• Plumb – exactly vertical or perpendicular.

• Plumb Bob – a lead weight attached to a string. It is the tool used in determining absolute verticality on a surface or plane.

• Ply – a term denoting the number of layers of roofing felt, veneer in plywood, or layers in built-up materials.

• Purlin – a horizontal structural member that transfers loads from the primary structural framing to the columns and/or walls.

• Re-Roofing Service - Removal service of a deteriorated roof and installation of new roofing system.

• R-Factor or Value – a measure of insulation, or a measure of a material resistance to the passage of heat.  The higher the R value, the more insulating ability the product contains.

• Rake – the slope edge of a roof.

• Re-Cover – the addition of a new roof membrane over an existing deteriorated membrane.  Note: It does not involve removal of an existing roofing.

• Re-Roofing – removal of a deteriorated roof down to the deck (plywood) and installing a new roof.

• Reshingle Roofing - same as re-roofing.

• Roll Roofing – coated felts (i.e. smooth or mineral-surfaced).

• Roof Estimates - calculating the area of a roof.

• Roof Joist – the rafters of a flat roof, used to support the roof sheeting and roof loads.

• Saturated Felt – a felt that is impregnated with tar or asphalt.

• Sheathing or Sheeting – the structural wood panel covering the OSB or plywood, used over a surface joists or rafters (i.e. trusses) of a structure.

• Scupper – a collection opening through the parapet wall, created for peripheral drainage of the roof, usually a safety overflow to limit accumulation of ponded rainwater caused by clogged drains.

• Soffit – the area below the eaves and overhangs.

• Square – a unit of measure, equal to 10 by 10 feet, or 100 square feet. 

• Structural Lightweight Concrete – a type of concrete used in deck construction which weighs about two-thirds the amount of ‘normal concrete’ structural concrete.

• Tear-Off – the removal of all roof system components down to the structural deck (i.e. plywood), followed by the installation of a new roofing system.

• Thermal Insulation – a material applied to reduce the flow of heat.

• Thermoset – a material that solidifies heat.

• Tread – the walking surface (i.e. horizontal plank) board in a stairway.

• UL (Underwriters’ Laboratories) – an independent testing agency that checks electrical devices and other components for possible safety hazards.

• Valley – the internal angle formed by the intersection of two sloping roof planes.

• Vapor Drive – the movement of vapor across a barrier from areas of high pressure to areas of low pressure.

• Vapor Retarder – also known as a ‘vapor barrier’, it is a layer or layers of material used to reduce the flow of water vapor into a roof system.  A vapor retarder prevents warm humid air from contacting a cold surface.

• Vermiculite – a hydrous, silicate mineral that expands greatly when heated.  Exfoliation occurs when the mineral is heated sufficiently, and the effect is routinely produced in commercial furnaces. 

• Viscosity – the resistance of a liquid material to flow under stress; the ‘thicknesses’ of a liquid material.  As viscosity increases, the flow rate decreases.

• Warping – a distortion in the material.

• Wicking – the process of moisture movement by capillary action, as contrasted to movement of water vapor.

• Woven Valley – a method of valley construction in which shingles or roofing from both sides of the valley extend across the valley and are woven together by overlapping alternate course as they are being installed.