When you hear a roofing term that you don't understand, come to our
easy to use glossary for help. Your new roof is a large investment you
deserve to know and understand the terminology used by your builder,
contractor, and suppliers.
Just click on the first letter of the word you need defined:
- AAMA: American Architectural Manufacturers Association
- Absorption: The act or process of retaining foreign particles, such as gas or liquid, without transmission of these particles.
- ACI: American Concrete Institute
(1) The use of a strong acid to remove the surface of concrete thereby
exposing the aggregate. (2) The use of a strong acid to etch the surface
of material such as metal in order for that material to accept a primer
or Spray Polyurethane Foam (SPF).
- ACIL: American Council of Independent Laboratories
- Acrylic Coating: A coating system with an acrylic resin base.
- Acrylic Resin: Polymers of acrylic or met acrylic monomers often used as a latex base for coating systems.
Will corrode in the presence of moisture or a noble metal. (Noble
metals being those that are resistant to corrosion and oxidation in
moist air, unlike most base metals.)
- Adhere: The clinging of one surface to another, either molecularly or otherwise.
- Adhesion: The state of adhering.
- AFA: American Fiberboard Association
- AGC: Associated General Contractors of America
A surfacing or ballast for a roof system. Aggregate can be rock, stone,
crushed stone or slag, water-worn gravel, crushed lava rock, or marble
- AHA: American Hardboard Association
- AIA: American Institute of Architects
Air Blown Asphalt:
Asphalt produced by blowing air through molten asphalt held at an
elevated temperature. This procedure is used to modify properties of the
- Alligatoring: The cracking of the surfacing bitumen on a built-up roof, producing a pattern of cracks that resemble an alligator's hide.
- Aluminized Steel: Sheet steel with a thin aluminum coating on the surface to enhance the steel's ability to withstand weathering.
- Aluminum: A non-rusting metal used for metal roofing and the fabrication of gutter and flashings.
- Ambient Temperature: The temperature of the air.
When two metals are connected in an electrolyte, they will form a
galvanic cell with the higher metal in the galvanic series being the
anode. The anodic will oxidize and produce an electrical current that
protects the cathode from corrosion.
- ANSI: American National Standards Institute
- APA: American Plywood Association
- Application Rate: The rate at which a material is applied per unit area.
- Apron Flashing: A flashing located at the low end of a curb or penetration.
- Architectural Panel: A metal roof panel that usually requires solid decking underneath.
- Architectural Shingle: Shingle that provides a dimensional appearance. See also Dimensional Shingle.
A flashed assembly usually extending above the surface of the roof that
is anchored to the roof deck. It is used to relieve thermal stresses in
a roof system where an expansion joint is not required, or to separate
large roof areas.
- ARMA: Asphalt Roofing Manufacturers Association
- ASA: American Subcontractors Association
An incombustible fibrous mineral form of magnesium silicate formerly
used for fireproofing and sometimes used for the reinforcement of
- ASC: Associated Specialty Contractors
- ASHI: American Society of Home Inspectors
- ASHRAE: American Society of Heating, Refrigerating & Air-Conditioning Engineers, Inc.
A substance left as a residue after evaporating or otherwise processing
crude oil or petroleum. Asphalt can be refined to conform to various
roofing grade specifications:
A roofing asphalt conforming to American Society for Testing and
Materials (ASTM) Specification D 312, Type I. This asphalt is for use in
roofs that do not exceed a ¼ in 12 slope (2%). Flat Asphalt: A roofing
asphalt conforming to the requirements of ASTM Specification D 312, Type
II. This asphalt is for use in roofs that do not exceed a ½ in 12 slope
(4%). Steep Asphalt: A roofing asphalt conforming to the requirements
of ASTM Specification D 312, Type III. This asphalt is for use in roofs
that do not exceed a 3 in 12 slope (25%). Special Steep Asphalt: A
roofing asphalt conforming to the requirements of ASTM Specification D
312, Type IV. This asphalt is for use in roofs that do not exceed a 6 in
12 slope (50%).
- Asphalt Emulsion: A mixture of asphalt particles and an emulsifying agent such as bentonite clay and water.
- Asphalt Felt: An asphalt-saturated and/or asphalt-coated felt membrane. See also Felt.
- Asphalt Primer: See Primer.
Asphalt Roof Cement:
The proper name for Plastic Cement and Flashing Cement. Asphalt roof
cement consists of solvent-based bitumen, mineral stabilizers, and other
fibers (sometimes asbestos). Asphalt roof cement is categorized by ASTM
standard D 2822-91 (1997) or for non-asbestos, ASTM standard D 4586-93.
Plastic Cement is for use on low-slope surfaces and conforms to ASTM
Specification D 312, Type I; Specification D 449, Types I or II; or
Specification D 946. Plastic Cement is self-sealing, adhesive, ductile
and classified by ASTM Standard D 2822-91 Asphalt Roof Cement, and D
4586-92 Asphalt Roof Cement, Asbestos-Free, Types I and II. Flashing
Cement can be used on vertical surfaces, has a high softening point, low
ductility and conforms to the requirement of ASTM Specification D 312,
Types II or III; or Specification D 449, Type III.
- ASTM: American Society for Testing and Materials
- Atactic Polypropylene: A group of high molecular weight polymers formed by the polymerization of propylene.
- Attic: The open area above the ceiling and under the roof deck of a steep-sloped roof.
- AWPA: American Wood Preservatives Association
- AWS: American Welding Society
The method of fastening the back or upper side of a ply of roofing felt
or other component in a roof system so that the fasteners are covered
by the following ply.
Back-Surfacing: A fine
mineral material on the back side of roofing materials such as roll
roofing to keep them from sticking together while packaged.
A material installed over the top of a roof membrane to help hold it in
place. Ballasts are loose-laid and can consist of aggregate, or
- Bar Joist: See Steel Joist.
- Barrel Roof: A roof configuration with a partial cylindrical shape to it.
Base Flashing (membrane base flashing):
Plies of roof membrane material used to seal a roof at the vertical
plane intersections, such as at a roof-wall and roof-curb junctures. See
- Base Ply: The primary ply of roofing material in a roof system.
- Base Sheet: An asphalt-impregnated, or coated felt used as the first ply in some built-up and modified bitumen roof systems.
(1) A strip of wood usually fastened to the structural deck for use in
attaching a primary roof system such as tile. (2) A plastic strip, wood
strip, or metal bar which is used to fasten or hold the roof and/or base
flashing in place - also known as a Termination Bar.
- Bermuda Seam: A metal roof that has a step profile.
- Bird Bath: Small, inconsequential amounts of water on a roof that quickly evaporate.
- Bird Screen: Wire mesh installed over openings in order to prevent birds from entering a building or roof cavity.
Any of various flammable mixtures of hydrocarbons and other substances,
occurring naturally or obtained by distillation from coal or petroleum
that are a component of asphalt and tar and are used for surfacing roads
and for waterproofing.
continuous seal for preventing bitumen from leaking down into or off a
building. Is constructed by extending the base sheet or other non-porous
ply of felt beyond the edge of the field plies. It is then turned back
onto the top of the system and adhered. See also Envelope.
- Bituminous Emulsion: Bituminous particles suspended in water or other solution. See also Asphalt Emulsion.
- Bleeder Strip: A starter strip placed along rake edges for use in asphalt shingle roofing. See also Rake-Starter.
- Blind-Nailing: The use of nails so that they are not exposed to the weather in the finished roofing system. See Back-Nailing.
- Blister: A pocket of air trapped between layers of felt or membrane - usually caused by water or other foreign substances.
Pieces of wood built into a roof assembly used to stiffen the deck
around an opening, support a curb, or for use as a nailer for the
attachment of membranes or flashing.
- Blown Asphalt: See Air Blown Asphalt.
- Blueberry: A small bubble found in the flood coat of an aggregate-surfaced, built-up roof.
- BOCA: Building Officials and Code Administrators, International, Inc.
- BOMA: Building Owners and Managers Association, International
- Bond: The force(s) holding two components in positive contact.
- Bonding Agent: A chemical agent used to create a bond between two layers.
- Boot: A piece of material preformed to protect roof penetrations from dirt, moisture, and other foreign and/or damaging substances.
- Brake: A piece of equipment used for forming metal.
- Bridging: When membrane is unsupported at a juncture.
- British Thermal Unit (BTU): The heat energy necessary to raise the temperature of one pound of water one degree Fahrenheit - equivalent to a joule.
Embedding a ply of roofing material into hot bitumen or adhesive by
using a broom, squeegee, or other piece of equipment to eliminate voids
and help ensure adhesion.
- Buckle: A long, tented displacement of a roof membrane. Can occur over insulation and deck joints.
Built-Up Roof Membrane:
A roof membrane consisting of layers of bitumen, which serves as the
waterproofing component, with plies of reinforcement fabric installed
between each layer. The reinforcement material can consist of
bitumen-saturated felt, coated felt, polyester felt or other fabrics. A
surfacing is generally applied and can be asphalt, aggregate, emulsion
or a granule-surfaced cap sheet.
- Bundle: An individual package of shingles or shakes.
- BUR: An acronym for Built-Up Roof. See Built-Up Roof.
- Butadiene: A colorless, highly flammable hydrocarbon, C4H6, obtained from petroleum and used in the manufacture of synthetic rubber.
- Butt Joint: Where two separate, adjacent pieces of material abut.
A hydrocarbon radical, C4H9. Butyl has a rubber-like consistency, is
formed from the copolymerization of isobutylene and isoprene and is used
primarily in sealants and adhesives.
- Butyl Rubber: A butyl-based, synthetic elastomer.
- Butyl Tape: A sealant tape used in numerous sealant applications such as sealing sheet metal joints.
- CABO: Council of American Building Officials
- Calender: A machine used to laminate sheeting or for applying coating with a specified thickness and/or surface attribute.
- Calendering: A specific process used to manufacture some membranes such as PVC.
- Camber: A slight convex curve of a surface.
- Canopy: An overhang, usually over entrances or driveways.
- Cant: (1) Short for Cant Strip. (2) The act of installing foam at a right angle adjunct.
A triangular-shaped strip of material used to ease the transition from a
horizontal plane to a vertical plane. Cant strips can be made of wood,
wood fiber, perlite, or other materials.
- Cap Flashing: A material used to cover the top edge of base flashings or other flashings. See also Coping.
- Cap Sheet: A granule-surfaced membrane often used as the top ply of BUR or modified roof systems.
A device for locating moisture within a roof system by measuring the
ratio of the change to the potential difference between two conducting
elements that are separated by a non-conductor.
A substance that effects a chemical reaction and/or the rate at which a
chemical reaction takes place. In roofing, catalysts are used in SPF
- Cathodic: Metals low in the Galvanic Series.
- Caulk: A material with no elastomeric properties used for sealing joints.
- Caulking: The act of sealing a joint or of material.
The vaporization of a liquid under the suction force of a pump which
can create voids within the pump supply line. Cavitation will result in
off-ratio foam in Sprayed Polyurethane Foam applications.
- CCF: 100 cubic feet.
- C-Channel: A structural framing member that, when viewed cross-sectionally, has the shape of a "C."
A complex carbohydrate, (C6H10O5)n, that is composed of glucose units,
forms the main constituent of the cell wall in most plants, and is used
in the manufacturing of organic roofing materials.
- CERL: Construction Engineering Research Laboratory
- CG&E: See Chopped Glass and Emulsion.
- Chalk: A powdery residue on the surface of a material.
(1) A string on a reel in a container that can hold chalk. (2) A line
made on by pulling taut a string coated with chalk and snapping it.
- Channel Flashing: Flashing with a built-in channel for runoff; used where roof planes intersect other vertical planes.
- Chemical Resistance: A materials ability to retain its properties when it comes into contact with certain chemicals.
Chlorinated Polyethylene1 (CPE):
CPE is a flexible material with high tear strength, good chemical
resistance and patency towards UV radiation. As a result of the high
chlorine content (typically 30%) it is inherently difficult to ignite,
but releases hydrogen chloride during combustion. It suffers from an
extremely high permeability to gas. Resistance to most inorganic
chemicals is generally good, while resistance to hydrocarbons increases
with increasing chorine content. The material is used mainly as an
impact modifier for PVC and, to a lesser extent, LDPE and HDPE film.
Chlorosulfonated Polyethylene (NRCA Definition):
A synthetic, rubber-like thermoset material, based on high molecular
weight polyethylene with suphonyl chloride, usually formulated to
produce a self-vulcanizing membrane. Chlorosulfonated Polyethylene or
CSPE. Best know as Hypalon™, it was developed in 1951 by DuPont.
Chopped Glass and Emulsion (CG&E):
A roof coating that consists of asphalt or clay emulsion and glass
fiber reinforcement. The glass fiber comes in rope form and is
mechanically chopped into small pieces and then mixed with the emulsion
at the end of the spray gun so that the mixture is complete by the time
the surfacing hits the top of the roof. Standard mixture is 9 gallons of
emulsion and 3 pounds of glass fiber for every 100 square feet (36.5
Liters of emulsion and 1.5 kg of chopped glass for every 10 square
meters). The CG&E coating is then usually surfaced with a fibered
aluminum roof coating at rate of 1.5 gallons per 100 square feet (6
Liters per 10 square meters).
- Cladding: A material used to cover the exterior wall of a building.
A continuous metal strip used to secure two or more metal roof
components together. Commonly used along with coping or gravel stop on
- Clerestory (Clearstory): A room that extends above an abutting roof section of a building.
- Clip: A small cleat.
- Clipped Gable: A gable cut back at the ridge in a small hip configuration.
A method of valley application in which shingles from one side of the
valley extend across the valley while shingles from the other side are
installed over the top of those and then trimmed back approximately 2
inches from the valley centerline.
- Closure Strip: A material used to close openings created by joining metal panels or sheets and flashings.
Coal Tar Bitumen:
A proprietary trade name for Type III coal tar used in dead-level or
low-slope built-up roofs. It is not for use in roofs exceeding ¼ in 12"
- Coal Tar Pitch: A type of coal tar used in dead-level or low-slope built-up roofs. It is not for use in roofs exceeding ¼ in 12" (2%) slope.
- Coal Tar Felt: A roofing membrane saturated with refined coal tar.
- Coal Tar Roof Cement: A trowelable mixture of processed coal tar base, solvents, mineral fillers and/or fibers.
Coarse Orange Peel Surface Texture:
A surface showing a texture where nodules and valleys are approximately
the same size and shape. This surface is generally acceptable for
installing a protective coating.
Coated Base Sheet:
An asphalt-saturated base sheet membrane later coated with harder, more
viscous asphalt, thereby increasing its impermeability to moisture.
- Coated Felt: An asphalt-saturated ply sheet that has also been coated on both sides with harder, more viscous asphalt.
- Coating: A layer of material that is spray, roller, or brush applied over a surface for protection or sometimes decoration.
- Cohesion: Mutual attraction by which the elements or particles of a body or substance are held together.
- Coil Coating: The application of a finish to a coil of metal or other material.
- Cold Forming: The process of shaping metal into desired configurations at ambient room temperature.
Cold Process Built-Up Roof:
A roof consisting of multiple plies of roof felts laminated together
with adhesives that usually come right out of a can or barrel and
require no heating.
- Collector Head: A component used to direct water from a through-wall scupper to a downspout. Also known as a Conductor Head.
- Column: A vertical structural member placed on a footing or foundation used to support horizontal above-ground building components.
A term used to describe an installation of finishing slate at the ridge
of a roof whereby the slates on one side project beyond to the apex of
- Combustible: Capable of igniting and burning.
A type of shingle used in steep-slope roofing and generally comprised
of weathering-grade asphalt, a fiberglass reinforcing mat, an adhesive
strip, and mineral granules.
Compounded Thermoplastics1 (NRCA Definition):
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. Some of the membranes listed in this
generic category are CPA, EIP, NBP, and TPA.
A method of installing asphalt roll roofing material in which all nails
or fasteners are driven into the underlying roofing and covered by an
- Condensate: The liquid resulting from condensation.
- Condensation: The conversion of water vapor to liquid state when warm air comes in contact with a cold surface. See also Dew Point.
The transmission or conveying of something through a medium or passage,
especially the transmission of electric charge or heat through a
conducting medium without perceptible motion of the medium itself.
- Conductor Head: A component used to direct water from a through-wall scupper to a downspout. Also known as a Collector Head.
- Construction Joint: A constructed joint where two successive installments of concrete come together.
- Contact Cements: Adhesives used to adhere or bond roofing components.
The piece of material used to cover the top of a wall and protect it
from the elements. It can be constructed from metal, masonry, or stone.
A reddish-brown element that conducts heat and electricity very well.
It is also used as a primary roof material as well as a flashing
component. Copper turns a greenish color after being exposed to the
weather for a length of time and appears in the middle of the Galvanic
- Cornice: A horizontal projecting part that crowns the wall of a building.
- Counter Batten: Wood strips installed vertically on sloped roofs over which horizontal battens are secured.
Formed metal sheeting secured to walls, curbs, or other surfaces, for
use in protecting the top edge of base flashings from exposure to
Course: (1) The term used for each row
of roofing material that forms the roofing or flashing system. (2) One
of multiple layers materials applied to a surface. For example, a
three-course flashing consists of a layer of mesh or other reinforcing
material sandwiched between two layers roofing cement.
In roofing, a heavy bead of sealant material installed at the point
where vertical and horizontal planes meet. It is used to eliminate the
90º angle. See also Fillet.
- Cover Plate: A metal strip sometimes installed over the joint between formed metal pieces.
- Coverage: The surface area covered by a material.
- CPA: Copolymer Alloy.
- CPE: Chlorinated Polyethylene.
- Crack: A separation or fracture occurring in a material.
Time in seconds at a given temperature when the A and B (isocyanate and
resin) components of SPF will begin to expand after being mixed.
- Creep: Movement of roof membrane causing the roof system to be deformed.
A roof component used to divert water away from curbs, platforms,
chimneys, walls, or other roof penetrations and projections. See also
- Cross Ventilation: The effect of air moving through a roof cavity between vents.
- CRREL: Cold Regions Research and Engineering Laboratory
- Crow's Nest: See Cupola.
- CSI: Construction Specifications Institute
- CSM: ASTM designation for Chlorosulfonated polyethylene. See CSPE.
- CSPE: Chlorosulfonated polyethylene.
- Cupola: A relatively small roofed structure set on the ridge of a main roof area. Also known as a Crow's Nest.
(1) A raised member used to support skylights, HVAC units, exhaust
fans, hatches or other pieces of mechanical equipment above the level of
the roof surface, should be a minimum of eight inches (8") in height.
(2) A raised roof perimeter that is relatively low in height.
A process by which a material is forms permanent molecular linkages by
exposure to chemicals, heat, pressure, and/or weathering.
- Cure Time: The time necessary to effect curing.
- Curing Agent: A material additive that alters chemical activity between the components resulting in a change in the rate of cure.
- Curing Compound: A liquid that is applied to newly installed concrete that slows water loss while curing.
- Cutback: Bitumen thinned by solvents that is used in cold-process roofing adhesives, roof cements, and roof coatings.
A detail designed to seal and prevent lateral water movement in an
insulation system, and used to separate different sections of a roofing
- Cutout: The open area between shingle tabs. Also known as a "throat."
- Dampproofing: Treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure.
- Dead Level: Refers to a roof with no slope or pitch.
A roofing asphalt conforming to the requirements of ASTM Specification D
312, Type I. This asphalt is for use in roofs which do not exceed a ¼
in 12 slope (2%).
- Dead Loads: Permanent, non-moving loads on a roof resulting from the weight of a building's components, equipment, and the roof system.
- Deck: The structural component of the roof of a building that provides the substrate to which the roofing system is applied.
- Decking: See Deck.
- Deflection: The downward displacement of a structural member under load.
- Degradation: A decline in the appearance, structure, or properties, of a material or substance.
- Delamination: Separation of laminated layers of a material or system.
- Dew Point Temperature: The temperature at which water vapor turns to liquid in cooling air at the existing atmospheric pressure and vapor content.
- Diaphragm: A type of structural roof deck capable of resisting shear that is produced by lateral forces such as wind or seismic loads.
- Diffusion: The movement of a substance such as water vapor from regions of high concentration to regions of lower concentration.
A shingle that is textured, or laminated to produce a three-dimensional
effect. Also known as Laminated and Architectural Shingles. Please be
aware that there are also shingles being produced that can be classified
as Dimensional but not as Laminated. These shingles are comprised of a
single piece of material rather than two different materials laminated
Dimensional Stability: The ability of
a material to retain its current properties and to resist a change in
size resulting from exposure to temperature changes and moisture.
- Dome: A roof with a partial-spherical shape.
- Dormer: A framed projection through the sloping plane of a roof.
- Double Coverage: Installing roofing so that there is twice the materials used resulting in a double layer of roofing.
Installing one layer of gravel in a flood coat of hot bitumen, removing
the excess gravel and then installing a second layer of gravel in
another flood coat of hot bitumen.
conduit for carrying water from a gutter, scupper, drop outlet or other
drainage unit from roof to ground level. Also known as a Leader Pipe.
- Drain: a device used to carry water off of a roof.
A steel flashing bent at a 90º angle that is placed along the outer
perimeter of steep sloped buildings; used to help direct runoff water
away from the building. Drip Edge resembles nosing except that it has an
outwardly-angled bottom edge (preferably hemmed).
- Dry Bulb Temperature: The temperature of air in degrees Fahrenheit measured by an ordinary thermometer.
- Dry Film Thickness: The thickness in mils (thousandths of an inch), of a dried coating or mastic.
(1) The process of installing the underlayment in steep slope roofing.
(2) Making a low-slope roof watertight. Does not always mean getting all
of the required plies installed.
Dry Rot: Wood
rot caused by certain fungi. Dry rot can result from condensation
build-up, roof leaks that go untended, or from other problems. Dry rot
will not remain localized. It can spread and damage any lumber touching
the affected area.
- Dual Level Drain: An item that will permit drainage at two different levels.
- Dynamic Load: Any moving load on a roof such as people and equipment. Wind can also be considered a Dynamic Load.
- Eave: A roof edge that extends out past the exterior wall line.
- Eaves-Trough: Another name for Gutter.
- ECH: Polyepichlorohydrin.
- Edge Stripping: Roofing material used to seal perimeter edge metal and the roof itself.
The installation of vent material along a roof edge (e.g., Starter
Vent) as part of a ventilation system. Edge vent material should be used
in conjunction with other venting material (e.g., ridge vent) as it not
intended for use by itself.
- Elastomer: A material which, after being stretched, will return to its original shape.
- Elastomeric: Properties of a material that will permit it to return to its original shape after being stretched.
- Elastomeric Coating: A coating that can be stretched to twice its dimensions and that will return to original when tension is released.
- Elongation: The ability of a material to be stretched or lengthened.
In roofing, to uniformly press one material into another, such as
aggregate into bitumen, roofing felt into bitumen, or granules into a
- Emulsion: Fine particles suspended in a liquid solution. See also Asphalt Emulsion
- End Lap: The extension of one component of material past the end of an adjacent piece of material.
A continuous seal for preventing bitumen from leaking down into or off a
building. Is constructed by extending the base sheet or other
non-porous ply of felt beyond the edge of the field plies. It is then
turned back onto the top of the system and adhered.
- EPDM: Ethylene Propylene Diene Monomer.
- Epichlorohydrin (ECH): A synthetic rubber material similar to EPDM with a stronger resistance to animal fats and oils than EPDM.
- Epoxy: A type of synthetic, thermosetting resins that produce tough, hard, chemical-resistant coatings and adhesives.
A nonstructural wall or screen constructed around rooftop equipment
such as HVAC units, curbs, etc. to hide the look of the equipment and
make the structure more aesthetically pleasing.
Equiviscious Temperature (EVT):
The temperature at which a bitumen attains the proper viscosity for use
in built-up roofing. There is usually a twenty-five degree Fahrenheit
(25º F) variance permitted above and below the recommended EVT. The EVT
is measured in application equipment just prior to application using a
standard thermometer or it can be measured just after application using a
The following tables have SAMPLE EVT temperatures.
- ASPHALT - ASTM D 312
- Asphalt Type Mop Application (º F) Mechanical Spreader Application (º F)
- Type I Dead Level 350 ± 25 375 ± 25
- Type II Flat 400 ± 25 425 ± 25
- Type III Steep 425 ± 25 450 ± 25
- Type IV Special Steep 450 ± 25 475 ± 25
- COAL TAR - ASTM D 450
- Coal Tar Type Mop Application (º F) Mechanical Spreader Application (º F)
- Type I Pitch 360 ± 25 380 ± 25
- Type III Bitumen 375 ± 25 400 ± 25
- Ethylene Propylene Diene Monomer (EPDM): A thermoplastic rubber with high tear strength that can be cross-linked by both peroxides and sulfur.
- EVT: Equiviscous Temperature
A device used to vent air from the roof cavity with vents that are
installed on or near the higher portions of the roof such as the ridge.
- Expansion Cleat: A cleat designed to handle thermal movement of the metal roof panels.
A built-in separation between building sections to allow for free
movement between the sections without damaging the buildings structural
- Exposed-Nail Method: A method of installing roll roofing materials to where all nails/fasteners are visible and exposed to the elements.
The portion of the membrane that is not overlapped by the succeeding
ply or course. Or, the portion of the roofing material exposed to the
weather after being installed.
- Extrusion: The process of manufacturing and/or shaping a material by forcing it through a die.
- Eyebrow: A small, shed roof protruding from the main roof or located on the side of a building below the level of the main roof.
Factory Mutual Research Corporation (FMRC):
As it relates to roofing - a division of Factory Mutual System that
tests and classifies roof components and systems for their resistance to
fire, traffic, impact, weathering, and wind-uplift. The various
organizations of Factory Mutual are owned or directed by Allendale
Insurance, Arkwright, and Protection Mutual Insurance.
A splice/seam made in the roofing material by the manufacturer. It is
preferable during installation to cut these splices out of the membrane.
- Fading: Losing brightness or brilliance-dim.
A reduction in the softening point temperature of asphalt that occurs
when asphalt is overheated for pro-longed periods of time.
Vertical roof trim located along the perimeter of a building, usually
below the roof level. Its use can be either decorative or for
- Fasteners: Devices used to secure roof system components.
Strips of wood that are placed along the butt ends of wood shingles to
form a somewhat smooth surface so that the shingles can be roofed over
Felt: A roofing sheet made of
interwoven fibers. The fibers can be wood or vegetable for Organic
Felts, glass fibers for fiberglass felts, polyester, or asbestos.
- Felt Machine: A machine that will install bitumen and felt at the same time.
- Ferrule: A metal sleeve used as a spacer to keep gutter from being beat up when secured to fascia with spikes.
- Fiberglass Insulation: Insulation composed of glass fibers used to insulate walls and roofs. It can be rigid board or blanket insulation.
- Field of the Roof: Refers to the central part of a roof away from the perimeter.
- Field Seam: A non-factory material seam made by joining overlapping seams together with adhesives, heat welders, or other means.
- Filler: An inert ingredient added to roofing materials in order to alter their physical characteristics.
- Fillet: A sealant material installed at horizontal and vertical planes to remove 90º angles.
- Film: A membrane or sheeting material with a nominal thickness of 10 mils or less.
- Film Thickness: The thickness of a membrane or coating that is expressed in mils (thousandths of an inch).
- Fin: A sharp protrusion in a roof deck that can damage roof components.
A fine mineral material on the surface of roofing materials to prevent
them from sticking to surfaces. 50% of this material has to pass through
a sieve with holes that are 1/35" in size (#35 sieve).
An opening along the exposed edge of an installed ply of felt caused by
shifting the ply during installation. Repair these by making a slice
along their entire length and feathering two plies of felt over the
fishmouth for a minimum coverage of one foot all the way around.
- Flaking: Occurs when a coating loses its cohesion.
- Flame Retardant: A substance used to impede a material's tendency to burn or ignite.
Per ASTM E 84, a measure of relative combustibility. The flame spread
of a tested material is rated relative to asbestos cement board (flame
spread = 0) and red oak flooring (flame spread = 100).
- Flammability: The ability of a material to burn or ignite.
A projection edge of a roof component such as flashings, skylight
frames, pre-manufactured curbs, etc. Usually refers to the part that
sits on the roof surface.
- Flash: To install flashing components.
- Flash Point: The lowest temperature of a liquid material at which combustion will occur when air reaches its surface.
Components used to seal the roof system at areas where the roof
covering is interrupted or terminated. For example, pipes, curbs, walls,
etc. all have special components that, when correctly installed, will
help prevent moisture entry into the roof system or building.
A trowelable mixture of solvent-based bitumen and mineral stabilizers.
Flashing cement that may contain asbestos stabilizers is categorized by
ASTM standard D 2822-91 (1997) or for non-asbestos, ASTM standard D
4586-93. Flashing Cement is the term for Asphalt Roof Cement that can be
used on vertical surfaces and has a high softening point, low ductility
and conforms to the requirement of ASTM Specification D 312, Types II
or III; or Specification D 449, Type III. See also Asphalt Roof Cement
and Plastic Cement.
- Flashing Collar: A flashing component used to seal soil pipe vents, hot stacks or other roof penetrations.
A type of interlocking two separate metal panels by folding one panel
over on top itself and the folding the other down under itself and then
hooking the panels together.
- Fleece: Mats or felts used as a membrane backer and composed of fibers.
The surfacing layer of bitumen into which aggregate is embedded on an
aggregate-surfaced built-up roof. A flood coat is applied at an
approximate rate of 45 to 60 pounds per square (100 square feet).
- Flood Test: A water test performed to determine the effectiveness of a roof covering.
- Flow: To become fluid in character.
- Fluid-Applied Elastomer: A liquid elastomeric material that cures to form a continuous waterproofing membrane.
- FM: Short for Factory Mutual Research Corporation.
- Foam Stop: The edge metal used to terminate Sprayed Polyurethane Foam.
An structurally-framed opening in a roof of a building for use in
installing large items such as HVAC units, skylights, or ventilators.
- Froth Pack: A term used to describe small, disposable aerosol cans of SPF.
- G-90: A coating weight for galvanized sheet metal, 0.90 ounces of zinc per sq. ft., measured on both sides of the sheet.
- Gable: A triangular-shaped portion of the endwall of a building directly under the sloping roof and above the Eave line.
- Gable Roof: A roof configuration that has gable ends.
- Gable-On-Hip Roof: A roof configuration with hips coming up from the eave corners that terminate into a gable roof.
- Galvalume: Trade name for a protective coating composed of aluminum zinc.
- Galvanic Action: A reaction between different metals in the presence of an electrolyte.
- Galvanize: To coat with zinc.
Steel that is coated with zinc to aid in corrosion resistance.
Galvanized steel for use in roofing should be Hot-Dipped Galvanized with
a G-90 coating.
- Gambrel: A roof that has two different pitches.
A standard of measurement. For instance the thickness of sheet metal or
the diameter of wire. The thicker the wire or metal, the lower the
Geodesic Dome: A geodesic dome uses a
pattern of self-bracing triangles in a pattern that gives maximum
structural advantage, thus theoretically using the least material
possible. (A "geodesic" line on a sphere is the shortest distance
between any two points.) The first contemporary geodesic dome on record
was designed by Walter Bauersfeld.
- Girt: A horizontal beam place between support columns that is used for attaching wall cladding.
(1) In the manufacturing of roofing materials - a sheet comprised of
bonded glass fibers prior to being saturated with bitumen. (2) short for
asphalt or coal tar saturated fiberglass felt membrane.
(1) The uppermost layer of asphalt on a smooth-surfaced built-up roof
membrane, usually a reflective surfacing is installed over it. (2) A
thin coat of bitumen applied to help protect the roof membrane when
application of additional felts or the flood coat and aggregate
surfacing are delayed.
- Grain: A unit of measure for the mass of moisture: a unit of weight equal to 0.002285 ounces or 0.036 dram.
A small aggregate, naturally or synthetically colored, used to surface
cap sheets, shingles, and other granule-surfaced roof coverings.
- Gravel: Aggregate consisting of rock fragments or pebbles.
A flanged, sheet metal edge flashing with an upward projection
installed along the perimeter of a roof to stop the flow of bitumen over
- Grout: A thin mortar used to fill cracks in masonry and tile.
- Grout (Non-Shrink): A cementitious material used to partially fill penetration pockets (pitch pans). A pourable sealer is used afterward.
A channel (usually sheet metal) installed along the downslope perimeter
of a roof to convey runoff water from the roof to the drain leaders or
- Half Gable Roof: See Shed Roof.
- Hand-Tabbing: Applying spots of adhesive to shingle tabs.
- Hatch: A unit used to provide access to a roof from the interior of a building.
- Headlap: The distance that the topmost ply of roofing felt overlaps the undermost ply or course.
- Heat Seaming: See Heat Welding.
Thermal energy going from an area of higher temperature to an area of
lower temperature by conduction, convection, or radiation.
Fusing the seams of separate sections of roofing material together
through the use of hot air or an open flame and pressure. Also known as
- Hem: The edge created by folding metal back on itself. Metal is hemmed for safety and strength reasons.
- Hip: The angle formed by the intersection of two sloping roof planes.
A roof that rises by inclined planes on all sides of a building. The
line where two adjacent sloping sides of a roof meet is called the Hip.
- Hoist: A mechanical lifting device. A hoist can be hand or electrically operated.
- Holiday: An area where a liquid-applied material is missing.
- Honeycomb: Small voids left in concrete because the mortar failed to fill the spaces around the aggregate.
- Hot: Slang for hot bitumen.
- Humidity: The amount of water vapor in the air.
- HVAC: Acronym for Heating, Ventilating, and Air Conditioning.
- Hypalon: The trademark name for Chlorosulfonated Polyethylene (CSPE), which is a single-ply roofing material.
- ICBO: International Conference of Building Officials, responsible for The Uniform Building Code.
Ice formed at the transition from a warm surface to a cold surface,
such as along the overhang of a house. The build-up of ice is the result
of ice or snow melting on the roof area over the warmer, living area of
a building and then refreezing when it runs down and reaches the
- Ignition Temperature: The minimum temperature at which a material will combust.
- Impact Resistance: A roof assembly's ability to withstand the impact from falling objects such as hail.
To saturate; in roofing, asphalt impregnated fiber glass roofing felts
are fiber glass mats that have been completely permeated with asphalt
- Infrared Thermography: The use of an infrared camera to detect moisture in roof insulation.
- Inorganic: Involving neither organic life nor the products of organic life; relating to compounds not containing hydrocarbon groups.
- Insect Screen: Material used to inhibit an insects ability to enter a building through openings in a roof such as vents.
Material used to help maintain a certain temperature in a building by
reducing the flow of heat to and from that building. See also Thermal
Intake Ventilation: The part of a
ventilation system used to draw fresh air in. Usually vents installed in
the soffit or along the eaves of a building.
A waterproof material usually installed between adjacent rows of wood
shakes to help with the roof's waterproofing characteristics.
- Interlocking Shingles: Shingles that lock together to provide wind resistance. See also T-Lock.
- Internal Pressure: Atmospheric pressure inside a structure that correlates to the number and location of openings and air leaks.
Inverted Roof Membrane Assembly (IRMA®):
A variation of the "Protected Membrane Roof Assembly" in which
Styrofoam® brand insulation is used. IRMA® and Styrofoam® are registered
trademarks of the Dow Chemical Company.
- IRWC: Institute of Roofing and Waterproofing Consultants
- ISANTA: International Staple, Nail and Tool Association
A highly reactive organic chemical containing one or more Isocyanate
groups - a basic component in Sprayed Polyurethane Foam (SPF) systems
and some polyurethane coating systems.
- Jack: See Roof Jack.
- Joint Tape: Tape used to seal joints between insulation boards.
- Joist: Any of the parallel horizontal beams set from wall to wall to support the boards of a floor, ceiling, or roof of a building.
- Knee Cap: Sheet metal trim that fits over a panel rib after it has been cut and bent.
An accumulation of fine, powdery aggregate particles on fresh cement
caused by the upward movement of water - indicates that too much water
was used in the mix resulting in poor surface adhesion for a
- Laminated Shingles: See Dimensional Shingles or Architectural Shingles.
- Lap: The part of the roofing material that overlaps a section of adjacent material.
- Lap Cement: Asphalt-based roof cement used to adhere overlapping plies of asphalt roll roofing.
- Lap Seam: Where two material that overlap are sealed together.
- Lead: Metal used for flashing material.
- Leader Head: A component used to direct water from a through-wall scupper to a downspout. Also known as a Collector Head.
A conduit for carrying water from a gutter, scupper, drop outlet or
other drainage unit from roof to ground level. Also known as Downspout.
- Lift: The rise in Sprayed Polyurethane Foam (SPF) resulting from a pass.
- Live Loads: Temporary items on a roof such as equipment, people, snow, etc. that the roof must be designed to support.
- Loose-Laid Roof Membranes: Roofing material attached only at the perimeter and at penetrations and held in place by ballast, pavers, or other materials.
(1) A steep-sloped roof located at the perimeter of a building and
usually used for decorative purposes. (2) The upper story formed by the
lower slope of a mansard roof.
- Mansard Roof: A steeper roof that terminates into a lower sloped roof at its high point.
- Masonry: Refers to bricks, concrete, or concrete blocks.
- Mastic: See Asphalt Roof Cement.
- Mat: A thin layer of woven, non-woven, or knitted fiber used to reinforce a material.
Material Safety Data Sheets (MSDS):
Written descriptions of the chemicals in a product provided by the
product's manufacturer. MSDS also contain other information such as
emergency procedures and safe handling.
- MBMA: Metal Building Manufacturers Association
- MCA: Metal Construction Association
Damage to a roof by means of items puncturing or otherwise
unnecessarily penetrating the roof system or any of its components.
Screws or nails stuck in the roof and heel marks along base flashings
are examples of mechanical damage.
- Mechanical Fasteners: Devices such as screws, plates, battens, nails, or other materials that are used to secure roofing materials.
The portion of the roofing system that serves as the waterproofing
material. Can be composed of one material or several materials laminated
Metal Flashing: Roof components made
from sheet metal that are used to terminate the roofing membrane or
material along roof edges. Metal flashings are also used in the field of
the roof around penetrations.
- Meter: A metric unit of length measurement equal to 39.37 inches.
A unit of measure equal to 0.001 inches (1/1000 in., or one
one-thousandth of an inch) used to indicate the thickness of a roofing
- Mildew: A superficial coating or discoloration of organic materials caused by fungi, especially under damp conditions.
- Millimeter: A metric unit of measure equal to one one-thousandth (0.001) of a meter, or 0.03937 inches.
- MIMA: Mineral Insulation Manufacturers Association
- Mineral Fiber: Inorganic fibers of glass or rock.
- Mineral Granules: See Granules.
- Mineral-Surfaced Roofing: Roofing materials with a top surface consisting of mineral granules.
- Miter: The joint made by two diagonally cut pieces put together.
A group of codes and standards accepted by more than one of the
Building Code regulatory agencies such as Southern Building Code
Congress International (SBCCI), Building Officials and Code
Administrators (BOCA), and the International Conference of Building
- Modified Bitumen: A bitumen modified by one or more polymers such as Atactic Polypropylene (APP), styrene butadiene styrene (SBS).
Moisture Relief Vent:
A vent installed through the roofing membrane to relieve moisture vapor
pressure that has been trapped within the roofing system.
A survey of a roof specifically to detect the amount of moisture
present in the roof system. Devices used in moisture surveys can be
capacitance meters, infrared cameras, and nuclear scanners. Infrared
scans can be done from the air or on the surface of the roof.
Capacitance and nuclear scans are done on the roof surface. It is argued
that the most accurate scans are done from the surface of the roof with
the most accurate of these being nuclear scans.
- Mole Run: A term used to describe a ridge in a roof membrane that is not the result of improper deck or insulation joints.
- Monolithic: Used to describe something without seams; formed from a single material.
- Monomer: A simple molecule that can combine with other to form a polymer.
- Mop-and-Flop: A roofers' term where the back side of a roofing material is mopped, then the piece is turned over and set in place.
- Mopping: To apply hot asphalt or coat tar using a hand mop or mechanical applicator.
- Mud Cracking: Surface cracking of a material that looks similar to dried, cracked mud.
- Multiple Coats: More than one layer of coating applied to a substrate.
- NAHB: National Association of Home Builders
A piece of lumber, preferably treated, that is secured to the deck,
walls, or to premanufactured curbs. Nailers are used to receive
fasteners for roof membranes. Generally, nailers are installed wherever
it is necessary to secure base flashings and edge metal.
Refers to a specific method or pattern at which nails are applied. For
instance, a nailing pattern for base sheets on plywood roof decks can be
"Nine and Eighteen". This means one row of nails on the outside edge of
the sheet set at nine inches (9") on center, and two rows in the center
of the sheet, each set at eighteen inches (18") on center.
- Neoprene: A synthetic rubber produced by polymerization of Chloroprene for use in liquid-applied and sheet-applied elastomeric roofing.
To overlay existing shingles with new shingles and butt the top edge of
the new shingle up against the bottom edge of the existing shingles.
- Net Free Vent Area: The area permitting unrestricted air flow.
In the meter-kilogram-second system, the unit of force required to
accelerate a mass of one kilogram one meter per second per second (s²).
- NICA: National Insulation Contractors Association
To temporarily seal the edge of a roof membrane in order to protect it
from moisture entry. Also known as Night Tie-Off and Water Cut-Off.
- Ninety-Pound: Granule-surfaced, fiberglass, or organic felt roll roofing that has a mass of approximately 90 pounds per 100 square feet.
- NIST: National Institute of Standards and Technology
- Noble: In reference to metal, inert, or inactive.
- No-Cutout Shingle: A shingle made of one solid strip of material.
- Non-Breathing Membrane: A membrane that does not permit water vapor or air to permeate it.
- Non-Flammable: Material with no measurable flash point.
- Non-Friable: Refers to a material's inability to be crushed or pulverized into a powder.
- Non-Volatile Content: The portion of a material that will not evaporate.
- Non-Vulcanized Material: A material that retains its thermoplastic properties throughout its service life.
- Nonwoven: Random arrangement of the reinforcement fibers of a scrim sheet or mat.
Metal flashing bent at a 90º angle and is installed around roof
perimeters, curbs, platforms, etc. in order to protect the edge of the
roofing system. Nosing should not be used in place of drip edge.
- NRCA: National Roofing Contractors Association.
- NTRMA: National Tile Roofing Manufacturers Association
Sprayed Polyurethane Foam (SPF) where the 1 to 1 ratio of the A and B
components has been compromised and which results in a lower quality
- Open Time: The time after an adhesive has been applied and permitted to cure when the two surfaces can be bonded.
- Open Valley: A valley where both sides of the roof are trimmed back from the centerline to expose the valley flashing material beneath.
- Orange Peel Surface Texture: A surface with a texture comparable to the skin of an orange upon which a protective coating may be applied.
- Organic: Formed from hydrocarbons.
- Organic Felt: An asphalt roofing base material manufactured from cellulose fibers.
- Organic Shingle: An asphalt shingle reinforced with organic material manufactured from cellulose fibers.
- ORNL: Oak Ridge National Laboratory
- OSB: Oriented Strand Board - often used as roof sheathing in place of plywood.
- Overlay: See Re-Cover.
- Overspray: The loss of spray particles (from coatings, Sprayed Polyurethane Foam (SPF), etc.) in the air.
- Pallet: A platform used to hold materials.
(1) The concave piece of "Pan and Cover" tile whose rounded surface
touches the top side of the roof substrate. (2) The flat part of a
roofing panel located between the ribs.
A sheet metal flashing that covers an equipment platform and is
designed to counter flash the base flashings surrounding the platform.
- Parapet Wall: That part of a perimeter wall that extends above the surface of the roof.
The term used to describe the application of one layer of Spray
Polyurethane Foam (SPF). The speed of a pass will determine foam
Pass Line: The distinct line formed
between two passes of Spray Polyurethane Foam (SPF). This line is the
top skin of the bottom pass of the SPF.
- Penetration: Any object that pierces the surface of the roof.
The maximum amount that a material can be lengthened or stretched
before breaking; expressed as a percentage of the original length of
Perlite: A natural volcanic
glass having distinctive concentric cracks and a relatively high water
content. In a fluffy heat expanded form, it is used in lightweight
insulating concrete, fire-resistant rigid insulation board (R = 2.78 per
inch) and potting soil.
Perm: A unit of water
vapor transmission, defined as one grain of water vapor per square foot
per hour per inch of mercury (Hg) pressure difference (1 inch of mercury
= 0.491 psi).
- Permeability: The rate of flow of a liquid or gas through a porous material.
A measure of the acidity or alkalinity of a solution, numerically equal
to 7 for neutral solutions, increasing with increasing alkalinity and
decreasing with increasing acidity. The pH scale commonly in use ranges
from 0 to 14.
Phasing: Installing roof system
components in separate time intervals. For instance, installing a base
sheet, and then two plies of roofing one day, and coming back and
installing the remaining two plies one or more days later. It is
generally not considered Phasing if the surfacing is applied at a later
- Picture Framing: Rectangular patterns seen in a roof that are created by buckles or ridges in the roof system or sumps in the substrate.
- PIMA: Polyisocyanurate Insulation Manufacturers Association
- Pinhole: A small hole in a coating, foil, membrane, or other roofing material.
- Pipe Boot: A prefabricated flashing piece used to flash around circular pipe penetrations. Also known as a Roof Jack.
- Pitch: Term used to describe Roof Slope and also short for Coal Tar Pitch.
Pitch Pocket (also known as Pitch Pan):
A flanged piece of flashing material placed around irregularly shaped
roof penetrations and filled with grout and a pourable sealer to seal
around the penetration in order to seal it from against moisture entry.
Pitch pockets are a good source of leaks and should be avoided if
- Pittsburgh Lock Seam: A method of interlocking two separate pieces of metal.
A term used to describe Type I asphalt roof cement. Plastic cement
should not be used on vertical surfaces. See also Asphalt Roof Cement
and Flashing Cement.
- Plastic Film: A flexible sheet made by the extrusion of thermoplastic resins.
- Plasticizers: Material incorporated into rubber and plastic in order to increase their flexibility and workability.
- Plenum: A space or enclosure in which air or other gas is at a pressure greater than that of the outside atmosphere.
- Ply: A layer of felt or other reinforcement material in a roof system.
- PMR: See Protected Membrane Roof.
Any of numerous synthetic polymers produced chiefly by reaction of
dibasic acids with Dihydric alcohols and used primarily as light,
strong, weather-resistant resins. In roofing, polyester is used to
Polymer: Any of numerous
natural and synthetic compounds of usually high molecular weight
consisting of up to millions of repeated linked units, each a relatively
light and simple molecule.
- Polymer Modified Bitumen: See Modified Bitumen.
Polymeric Methylene Diphenyl Diisocyanate (PMDI):
The "A" component in Spray Polyurethane Foam (SPF); when mixed with
"B", it forms polyurethane. PMDI is an organic chemical compound having
two reactive Isocyanate (-N=C=O) groups.
- Polymerization: The combining of monomers to produce polymers.
Any of various thermoplastic resins that are polymers of propylene.
They are hard, tough, and used to make molded articles and fibers.
Polyvinyl Chloride (PVC):
A thermoplastic polymer that can be compounded into flexible and rigid
forms through the use of plasticizers, stabilizers, fillers, and other
modifiers; rigid forms are used in pipes; flexible forms are used in the
manufacture of sheeting and roof membrane materials.
- Ponding: The accumulation of water at low-lying areas on a roof.
A small metal pin having a head on one end, inserted through aligned
holes in pieces of light gauge metal to be joined and then the head is
expanded to join the metal.
- Popcorn Surface Texture: A coarse surface texture of Spray Polyurethane Foam (SPF) considered unacceptable for coatings.
The drainage condition of a roof where all water is gone from the roof
surface within forty-eight hours of precipitation during normal drying
- Pot Life: The period of time during which a material with multiple ingredients can be applied or administered after being mixed together.
A type of sealant that is initially in liquid form commonly used in
conjunction with pitch pans to form a watertight barrier around
penetrations that are difficult to flash.
- Press Brake: A mechanical device used to form sheet metal into desired shapes and profiles.
A material that is applied to a surface in order to increase that
surface's ability to adhere to or work in conjunction with a
subsequently applied material.
pumping unit comprised of two (2) positive displacement pumps that is
designed to dispense two (2) components at a precise ratio. Used in SPF
and plural component coating applications.
Protected Membrane Roof (PMR):
A roof assembly in which the insulation and ballast are placed on top
of the membrane component. Commonly referred to as an "inverted roof
Psychrometer: An instrument that
uses the difference in readings between two thermometers, one having a
wet bulb and the other having a dry bulb, to measure the moisture
content or relative humidity of air.
- Puncture Resistance: The ability of a material to withstand being pierced by a sharp object.
- Purlin: Horizontal secondary structural member used to transfer loads from the primary structural members.
- PVC: Polyvinyl Chloride.
- Quarter Sized: Term for the size of hand sealant dabs, size of a U.S. 25¢ piece.
The measure of a material's resistance to heat flow. The higher a
material's R-value, the more it insulates. For more information on
R-Value, click on the term.
Racking: The method
of installing asphalt shingles where the shingles are installed
straight up to the ridge rather than horizontally. If this method is
used with 3-tab shingles, the throats of every other course will line
Rafter: The structural member extending
from the downslope perimeter of a roof to the ridge or hip and is
designed to support the roof deck and roof system components.
A groove that is cut into the side of a vertical surface such as a wall
or chimney that is used to insert a flashing element such as a reglet
Rake: The sloped perimeter
edge of a roof that runs from the eaves to the ridge. The rake is
usually perpendicular to the eaves and ridge.
- Rake-Starter: A starter strip placed along rake edges for use in asphalt shingle roofing. See also Bleeder Strip.
- RCI: Roof Consultants Institute
- RCMA: Roof Coatings Manufacturers Association
- RDCA: Roof Deck Contractors Association
- Re-Cover (Overlay): The installation of a new roof system over an existing system without removing an existing system.
- Reglet: A receiver, usually sheet metal, that counterflashing.
The exposed section of double thickness on Timberline® Series shingles -
also called dragon teeth. Shaped to imitate wood shake look on the
- Self-Sealant: Sealant installed on shingles. After installation, heat and sun will activate sealant to seal the shingles to each other.
- Selvage: The non exposed area on rolled roofing. Area without granules. Designed for nail placement and sealant.
- Shed Roof: Roof design of a single roof plane. Area does not tie into any other roofs.
- Side Laps: The area on rolled material where one roll overlaps the rolled material beneath it. Also called selvage edge on rolled roofing.
- Side Walls: Where a vertical roof plane meets a vertical wall. The sides of dormers etc.
- Soffit Ventilation: Intake ventilation installed under the eaves, or at the roof edge.
- Starter Strip: The first course of roofing installed. Usually trimmed from main roof material.
- Steep Slope Roofing: Generally all slopes higher than 4/12 are considered steep slopes.
- Stepflashing: Metal flashing pieces installed at sidewalls and chimneys for weatherproofing.
- Tab: The bottom portion of traditional shingle separated by the shingle cut-outs.
- Tear-Off: Removal of existing roofing materials down to the roof deck.
- Telegraphing: When shingles reflect the uneven surface beneath them. Ex: Shingles installed over buckled shingles may show some buckles.
- Transitions: When a roof plane ties into another roof plane that has a different pitch or slope.
- Underdriven: Term used to describe a fastener not fully driven flush to the shingles surface.
- Underlayments: Asphalt based rolled materials designed to be installed under main roofing material to serve as added protection.
- Valleys: Area where two adjoining sloped roof planes intersect on a roof creating a "V" shaped depression.
- Vapor: Term used to describe moisture laden air.
The finished wall inside of a structure, used in roofing to determine
how far up the deck to install waterproof underlayments at eaves.
- Waterproof Underlayments: Modified bitumen based roofing underlayments. Designed to seal to wood decks and waterproof critical leak areas.
- Woven Valleys: The method of installing valleys by laying one shingle over the other up the valley center.
in SPF-based roofing, the volume of foam per unit weight, normally
expressed as board feet per pound or board feet per 1000 pounds.
- Zinc: a metal that has application considerations including high expansion-contraction rates and low-temperature Restrictions.