Roofing Glossary
Glossary
Select a letter
Aggregate
crushed or water worn stone or slag that is used as a protective surface or ballast to anchor loosely laid or protected membrane assemblies
All Weather Elastomeric Mastic
a pliable asphaltic based elastomeric roofing mastic that can be installed in moist or wet conditions
Alligatoring
a term describing the cracking and shrinking of asphalt
Application Rate
the quantity per unit a material is applied i.e. 1 gallon per square
Area Divider
a raised detail installed to relieve stress in a roofing system on a roof deck that does not have an expansion join
Asbestos
a natural fibrous silicate material
Asphalt, Roofing
a dark brown to black material that is a residual by product of petroleum distillation
Asphaltic
containing or treated with asphalt
Asphalt Felt
an asphalt saturated or coated felt
Backnailing
the practice of mechanically fastening felts in addition to hot-mopping
Base Flashing
the flashing material that covers a cant strip or transition from the roof deck to a vertical surface
Base Ply
the lowermost or first ply of roofing felt installed
Base Sheet
a saturated or coated felt placed as the first ply in a multi-ply roof membrane assembly
Bitumen
an asphaltic type material derived from coal or petroleum
Bituminous
containing or treated with bitumen
Bituminous Emulsion
a suspension of minute globules of bituminous material in water or a water soluble solutions
Bituminous Grout
a mixture of bituminous material and fine sand that flows into place when heated
Blackberry
a small bubble or blister in the flood coat of a gravel surfaced roof system
Blind Nailing
the practice of nailing the back portion of a roofing felt so that the fasteners are not exposed to the weather when the system is completely installed
Blister
an enclosed pocket of air mixed with water or solvent vapor, trapped between two layers of felt or between the felts and substrate
Blocking
wood built into a roofing system generally above the substrate and around penetrations and perimeter of a deck to act as a nailer for attachment of membrane or flashing and provide a termination method for insulation
Bond
the adhesion and cohesive forces holding two roofing components together
Brooming
embedding a ply of roofing material into an adhesive with a broom or squeegee
Built-Up Roof Membrane
a continuous semi-flexible roof membrane assembly of saturated or coated felts and a bituminous material
Cant Strip
A beveled strip of material that eases the transition between vertical projections in a roof deck
Cap Flashing
A sheet of metal coping installed on the top of a higher wall such as a parapet
Capillarity / Capillary Action
The process of water being absorbed or “wicked” into a reinforcing fiber of a felt which can cause felt delamination
Cap Sheet
A granule surfaced membrane used as the top ply of a built up roofing system
Caulking
A material that is used to fill a crack or joint, generally remains flexible for an extended period to compensate for expansion
Coal Tar
A dark brown to black material that is the residue from partial evaporation or distillation of coal tar
Coal-Tar Pitch
A coal tar used as a waterproofing agent in low slope or dead-level roofing systems
Coal-Tar Felts
a felt that has been saturated with refined coal tar
Coated Sheet Felt
an asphaltic felt which has been additionally coated with a harder more viscous asphalt
Cold Process Roofing
a built-up roofing system that uses an asphaltic material which does not require heating to be applied
Condensation
the formation of water from vapor in the air upon contact of a cold surface
Coping
the covering piece on top of a wall exposed to the weather, usually sloped to shed water
Counterflashing
material usually metal that is installed into or on a vertical surface to cover the top edges of the base flashing material
Course
one layer of a series of materials which make a complete system
Coverage
the surface area consistently covered by a specific quantity of a particular material
Crack
a separation or fracture in a material generally caused by a stress or movement
Cricket
a false roof generally installed on horizontal roof valleys created by projections such as a chimney, to divert water around the projection. also called a saddle or saddle flashing
Cutback
a solvent thinned bitumen used in cold process, as a primer or coating
Cutoff
a detail designed to prevent lateral water movement. generally installed as a temporary seal to protect an existing system during reproofing. this detail is always removed.
Dampproofing
the treatment of a surface to resist the passage of moisture. this does not prevent the passage of moisture under pressure (hydrostatic pressure)
Dead Level
absolutely level, no slope
Dead-Level Asphalt
an asphalt that has a low softening point (temperature), and flows when warmed in the sun. always installed on dead level decks
Dead Loads
non-moving rooftop loads such as mechanical equipment, air conditioning equipment, or the deck itself
Deck
the structural surface to which the roofing system and insulation are installed
Delamination
Separation of the piles of a roofing system, or the separation of a ply itself
Dew Point
the temperature at which water vapor starts to condense in cooling air at the existing atmospheric pressure and vapor content
Double-Pour
the process of applying two layers of aggregate and bitumen to a built-up roof
Drain
a device that allows for the flow of water from a roof area
Dropback
a reduction in the softening point of bitumen that occurs when bitumen is heated in the absence of air
Edge Sheets
felt strips that are cut to a width narrower than a full sheet, used to start the felt shingling pattern at the roof edge
Edge Stripping
application of narrow felt strips to cover the joint between flashing and the built-up roofing system
Edge Venting
the practice of providing regularly spaced protected openings along the roofs edge to provide a means to relieve moisture vapor pressure
Elastomer
a material that returns to it’s approximate size and shape after being subjected to a stress and then released
Elastomeric
a rubber like synthetic polymer that will stretch when pulled and return quickly to its original shape when released
Embedment
the process of pressing a material into an adhesive
Emergency Repair
a repair which has been installed under adverse conditions to stop water penetration into a building, which must be replaced when weather conditions are more favorable
Emulsion
the intimate dispersion of an organic material and water achieved by using a chemical or clay emulsifying agent
Envelope
a continuous membrane edge seal formed at the perimeter and at the penetrations by folding the base ply back over the plies to prevent any asphalt seepage from the edges of the membrane
Equiviscous Temperature (EVT)
the recommended temperature of asphalt, plus or minus 25 degrees F at the time of application
Expansion Joint
a structural separation of a roof deck or walls to allow movement
Exposure
the amount of a roofing material that is left exposed to the elements after installation is complete or the time during which a portion or a roofing element is exposed to the weather
Fabric
a woven cloth of organic or inorganic filaments, threads, or yarns
Factory Mutual (FM)
an organization that classifies the fire and wind characteristics of materials for insurance companies
Factory Square
108 square feet of roofing material
Fallback
see “Dropback”
Felt
a flexible sheet manufactured by the interlocking or fibers through a combination of mechanical work, moisture, and heat
Felt Layer
a machine used for applying bitumen and built-up roofing felts
Fiber Glass Felt
see “Glass Felt”
Fine Mineral Surfacing
inorganic material used on the surface of roofing, more than 50% of the material must pass a No. 35 sieve test
Fishmouth
a half cylindrical or half conical opening formed by edge wrinkles
Flashing
the system used to seal membrane edges at penetrations or perimeters
Flashing Cement
a trowelable mixture of cutback bitumen and mineral stabilizers including asbestos or other inorganic fibers
Flat Asphalt
see “Dead-Level Asphalt”
Flood Coat
the top layer of the bitumen into which the aggregate is embedded on an aggregate-surface built-up roofing system
Fluid Applied
an elastomeric material, fluid at ambient temperature, that dries or cures after installation to form a continuous membrane. these systems do not generally incorporate a reinforcement membrane
Glass Felt
glass fibers bonded into a sheet with resin and suitable for impregnation in the manufacture of bituminous waterproofing materials, roof membranes, and shingles
Glass Mat
a thin mat composed of glass fibers with or without a binder
Glaze Coat
a thin layer of asphalt which is the top layer of a smooth surface roof or protects inner plies in delayed construction conditions
Gravel
Coarse, granular aggregate larger than sand, normally occurs due to natural erosion
Gravel Guard
a flanged device usually metal, designed to be a continuous finished edge for roofing material and to prevent loose aggregate from washing off the roof
Gravel Spot
see “Gravel Guard”
Gravel Stop
see “Gravel Guard”
Headlap
the minimum distance measured at 90 degrees from the eave along the face of a shingle or felt, from the upper edge of the nearest exposed surface
Hot Sheet
a felt that has been installed with hot bitumen
Hot Stuff / Hot
the roofer’s term for hot bitumen
Incline
The slope of a roof expressed either in percent or in the number of vertical unites per horizontal unit of run i.e. 4” in 12’ – 4 inches of vertical rise per 12 inches of horizontal run
Inorganic
being composed of materials other than plants or animals
Insulation
a material which retards the flow of heat or sound
Live Load
moving roof installation equipment, ice, snow, or rain
Mastic
a trowelable mixture of asphalt, volatile solvent and mineral fillers used as a cold coating in the application of flashing, for sealing around details
Membrane
a continuous flexible or semi-flexible roof covering that forms the water control element of a roofing system. An open weave fabric that is used to reinforce a waterproofing agent such as mastic
Mesh
a metallic screen or wire that is used to reinforce stucco or concrete. An open weave fabric that is used to reinforce a waterproofing agent such as mastic
Mineral Fiber Felt
a felt with mineral wool as its primary component
Mineral Granules
see “Fine Mineral Surfacing”
Mineral Stabilizer
a fine water insoluble inorganic material, used in a mixture with solid or semi-solid bituminous materials
Mineral Surfaced Roofing
built-up roofing materials whose top ply consists of a granule surface sheet
Modified Bitumen
a composite sheet consisting of a copolymer modified bitumen often reinforced and surfaced
Mole Run
a meandering ridge in a roof membrane which is not associated with insulation or deck joints
Mop and Flop
an application procedure where a material is placed upside down adjacent to its final installation point and coated with an adhesive then turned over and applied to the substrate
Mopping
the application of hot bitumen with a mop or mechanical applicator
Nineteen-inch Selvage
a granule surfaced roll material which has a 19 inch smooth portion to allow an overlap when installed, yielding a two-ply” system
Ninety-Pound
a granule surface roll roofing material that is composed or organic felt and has a mass of approximately 90 pounds per 100 square feet
Not To Exceed (NTE)
a pre-approved billing limit established with a client prior to responding and performing work
NRCA
National Roofing Contractors Association
Organic
of plant or animal origin
Parapet Wall
that part of any wall entirely above the roof
Parge Coat
a coating of cementious material to a wall to help resist hydrostatic pressure
Perlite
an aggregate used in lightweight concrete and in performed insulation boards
Permanent Repair
a repair that has been installed in such a way as to match the existing system and to outlast the surrounding roofing materials
Phased Application
the installation of a system in two or more separate time intervals, requiring nightly cutoffs
Picture Framing
the regular patterning of material around the perimeter of a building or deck joints
Pitch
see “Coal Tar”
Pitch Pocket
a flanged metal collar device that is placed around penetrations and filled with bitumen, mastic, or a pourable sealer
Plastic Cement
see “Flashing Cement”
Plastomeric
a plastic like polymer that can be molded, extruded, or cast into shapes that will soften when heated and harden when cooled
Ply
a layer of felt in a built-up roof membrane assembly
Polyester
an inorganic polymeric material which can be made into fibers that are used as reinforcement felts and fabrics
Pond
an area of a roof which does not completely drain water
Positive Drainage
the drainage conditions which allow water to be completely gone within 48 hours after a rainfall
Primer
a thin liquid bitumen applied to a surface to improve the adhesion of subsequent bituminous materials
Quoted Price
a fixed price given to a client to perform specific work
Rake
the slope edge of a roof at the first and last rafter
Re-Covering
the process of covering an existing roofing system with a new roofing system
Re-Entrant Corner
an inside corner of a surface, producing stress concentrations in a roofing or waterproofing system
Reglet
a groove in a wall or other surface adjoining a roof surface for use in the attachment of counterflashing
Reinforced Membrane
a roofing or waterproofing membrane reinforced with felts, mats, fabrics, or chopped fibers
Repair
the corrective materials and actions necessary to stop water from entering through the defect in the roofing system
Restore
the corrective materials and actions necessary to bring a neglected roofing system back to it’s best possible condition to extend it’s current life cycle
RIEI
Roofing Industry Educational Institute
Roof Cement
see “Flashing Cement”
Roof Divider
a building detail used to limit the size of continuous roof membrane, dividing a roof into smaller areas. the divider extends only to the roof deck and is not an expansion joint
Roof Mastic
see “Flashing Cement”
Slippage
the lateral movement of components of a roofing system
Slope
see “Incline”
Smooth-Surfaced Roofing
a roofing system that has been installed and whose top layer has no aggregate or ballast
Softening Point
the temperature at which bitumen begins to soften and flow
Solid Mopping
a continuous mopping of bitumen
Special Steep Asphalt
see “Steep Asphalt”
Split
a membrane tear resulting from tensile strength
Split Sheet
see “Nineteen-Inch Salvage”
Tear-off
The process of removing components or the entirety of a roofing system. Complete tear-offs usually involve stripping the roof down to the decking.
Thermal Imaging Service
A form of leak detection and energy-efficiency audit. It detects and indicates differences in temperature between sections of a rooftop.
Thermoplastic Membrane
A membrane (or ply) molded by the use of extreme heat. Membranes of this variety typically have much stronger seams. Material examples include TPO and PVC
TPO Roofing
Stands for thermoplastic polyolefin. A form of single ply, rubberized roofing that typically comes in a reflective white color.
Two-way Air Vent
Designed to allow limited air flow through a roofing system, lessening the negative effects of negative air flow.
Underlayment
A sheet placed over the surface of roof decking prior to installing the subsequent layers. Protects some protection against moisture infiltration.
Urethane Modified Acrylic Coating
A form of reflective roof coating designed for stronger resistance against water erosion.
Vents/Pipe Stacks
Types of rooftop penetrations, identifiable by their round shape.
Wind Load
The force placed on a building or roof as wind strikes it.
Wind Uplift
The force inflicted on a roofing system when upward pressure (created by wind) is greater than downward pressure. Measured in pounds per square foot.