Glossary of common roofing terminology
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A
AGGREGATE– Crushed stone, slag or water-worn gravel that comes in a wide range of sizes. Used to surface built-up roofs.
ALGAE– Rooftop fungus that can leave dark stains on roofing.
ALGAE DISCOLORATION– A type of roof discoloration caused by algae, also called fungus growth.
ANGLED FASTENERS– Roofing nails and staples driven into decks at angles not parallel to the deck.
ARMA– Asphalt Roofing Manufacturer’s Association. Organization of roofing manufacturers.
ALLIGATORING– A characteristic of asphalt which occurs during the aging process in which the loss of volatile oils and the oxidation brought about by solar radiation produces a pattern of cracks which resemble an alligator hide, because of the limited tolerance of asphalt to thermal expansion or contraction.
ASPHALT– A dark brown to black, highly viscous, hydrocarbon produces from the residue left after the distillation of petroleum, used as a waterproofing agent.
ASPHALT EMULSION– Asphalt and additives or modifiers suspended in water.
ASPHALT CONCRETE PRIMER– Asphalt based primer used to prepare concrete and metal for asphalt sealant.
ASPHALT PLASTIC CEMENT– Asphalt based sealant material, meeting ASTM D4586 Type I or II. Used to seal and adhere roofing materials. Also called mastic, blackjack, roof tar, bull.
ASTM-The American Society for Testing and Materials. Organization that sets standards for a wide variety of materials, including roofing.
ATTIC– The open area above the ceiling and under the roof deck of a steep-sloped roof.
B
BALLAST– Weight used to protect single-ply roofs or to prevent blow off of systems which are not adhered. Typically #2 stone is used.
BACK NAILING– The practice of nailing roofing felts to the deck under the overlap, in addition to hot mopping, to prevent slippage of felts.
BACK SURFACING– Fine mineral matter applied to the back side of shingles to keep them from sticking.
BARE SPOTS– Small areas on a roof where the top membrane has become exposed to the elements.
BARREL ROOF– A roof design which in cross-section is arched.
BASE FLASHING– That portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof covering.
BATTENS– 1″x2″x4′ wood strips nailed to the roof, upon which the field tile hangs.
BASE PLY– An asphalt-saturated and/or coated felt installed as the first ply with 4 inch laps in a built-up roof system under the following felts which can be installed in a shingle like fashion.
BATTEN PLATE– A formed piece of metal designed to cover the joint between two lengths of metal edge.
BITUMEN– Any of various mixtures of hydrocarbons occurring naturally or obtained through the distillation of coal or petroleum. (See Coat Tar Pitch and Asphalt)
BLISTER (BLISTERING)– An enclosed raised spot evident on the surface of a roof. They are mainly caused by the expansion of trapped air, water vapor, moisture or other gases. Blisters on a roof may involve only the coating, one or more plies of felt or may involve the whole membrane thickness.
BEAD– A semi-rounded strip (bead) of caulking material.
BEAM– A heavy main support structure, steel or wood running horizontally between columns or load bearing walls.
BLOW-OFFS– When shingles are subjected to high winds, and are forced off a roof deck.
BOND BREAKER– A substance or a tape applied between two adjoining materials to prevent adhesion between them.
BRAKE METAL– Sheet metal that has been bent to the desired configuration.
BUCKLING– When a wrinkle or ripple affects shingles due to organic underlayment.
BUILT-UP ROOF (BUR)– A roof consisting of multiple layers of reinforcing membrane and waterproofing materials.
BULB TEE– A specialized steel reinforcing member which support form boards and reinforces a gypsum deck, which when poured surrounds the Bulb-Tee.
BUNDLE– A package of shingles. There are 3, 4 or 5 bundles per square.
BUTT EDGE– The lower edge of the shingle tabs.
BUTTON CAP NAILS– Miami-Dade county specification fasteners for underlayment. This is the safest and most efficient way to adhere underlayment to the roof.
BUTTERFLY ROOF– A roof assembly which pitches sharply from either side toward the center.
C
C-CHANNEL– A structural framing member that, when viewed cross-sectionally, has the shape of a “C”.
CANOPY– An overhanging roof.
CANT STRIP– A beveled support used at the intersection of the roof deck with vertical surfaces so that bends in the roofing membrane to form base flashings can be made without breaking the felts.
CAP FLASHING (COPING)– A material used to cover the top edge of base flashings or other flashings.
CAP SHEET– One to four plies of felt bonded and top coated with bitumen that is laid over an existing roof as a treatment for defective roofs.
CAPACITANCE METER– 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.
CATALYST– 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 roofing.
CAULK– A material with no elastomeric properties used for sealing joints.
CAULKING– The act of sealing a joint or of material.
CAVITATION– 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.
CEMENT– A general term for a variety of trowelable mastics, asphalt or tar, which are used during roof construction and repair.
CHALKING– The resulting dust which occurs on a surface due to Ultra Violet degradation.
CHANNEL FLASHING– Flashing with a built-in channel for runoff; used where roof planes intersect other vertical planes.
CHECKING– A pattern of surface cracks running in irregular lines. When found in the top pour of an asphalt built-up roof, is the preliminary stage of alligatoring.
CHLOROSULFONATED POLYETHYLENE– 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.
CHEMICAL RESISTANCE– A materials ability to retain its properties when it comes into contact with certain chemicals.
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.
CLASS “A”– The highest fire-resistance rating for roofing as per ASTM E-108. Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.
CLASS “B”– Fire-resistance rating that indicates roofing materials are able to withstand moderate exposure to fire originating from sources outside the building.
CLASS “C”– Fire-resistance rating that indicates roofing materials are able to withstand light exposure to fire originating from sources outside the building.
CLEAT– A device made of formed sheet metal which is mechanically attached onto which the fascia flange of a metal edge is snapped, so as to protect against wind uplift.
CLEARSTORY– A room that extends above an abutting roof section of a building.
CLIPPED GABLE– A gable cut back at the ridge in a small hip configuration.
CLOSED CUT VALLEY– A method of valley treatment in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed two inches from the valley centerline. The valley flashing is not exposed.
COAL TAR PITCH (Tar)– A bituminous material which is a by-product from the coking of coal. It is used as the waterproofing material for tar and gravel built-up roofing.
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.
COATING– layer of any brush consistency product spread over a surface for protection.
COLD APPLIED– Products that can be applied without heating. These are in contrast to tar or asphalt which need to be heated to be applied.
COLD PATCH– A roof repair done with cold applied material.
COLLAR– A conical metal cap flashing used in conjunction with vent pipes or stacks usually located several inches above the plane of the roof, for the purpose of shedding water away from the base of the vent.
COMPATIBLE– Two or more substances which can be mixed or blended without separating, reacting, or affecting either material adversely.
COMPONENT– Any one part of an assembly associated with construction.
COMPOSITE BOARD– An insulation board which has two different insulation types laminated together in 2 or 3 layers.
CONDENSATION– The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.
CONDUCTOR– A pipe for conveying rain water from the roof gutter to a drain, or from a roof drain to the storm drain; also called a leader, downspout, or downpipe.
CONCEALED NAIL METHOD– Application of roll roofing in which all nails are driven into the underlying course of roofing and covered by a cemented, overlapping course. Nails are not exposed to the weather.
COOLING TOWER– A large device mounted on roofs, consisting of many baffles over which water is pumped in order to reduce its temperature.
CORE– A small section cut from any material to show internal composition. Cores are taken from the roof to verify the construction of the existing roof system. The deck is visable along with the insulation and the roof membrane.
CORNICE– A horizontal projecting course on the exterior of a building, usually at the base of the parapet.
CORROSION– The deterioration of metal by chemical or electrochemical reaction resulting from exposure to weathering, moisture, chemicals or other agents or media.
CONTROL JOINT– A control joint controls or accommodates movement in the surface component of a roof.
COPING– A construction unit placed at the top of the parapet wall to serve as a cover for the wall. Coping is typically metal, clay, or cement.
CORRUGATED– Folded or shaped into parallel ridges or furrows so as to form a symmetrically wavy surface.
COUNTER-FLASHING-The metal or siding material that is installed over roof-top base flashing systems.
COURSE– A single layer of building material.
CRAZING– A series of hairline cracks in the surface of weathered materials, having a web-like appearance.
CRICKET– A tapered construction detail that promotes drainage of water from behind an obstacle such as chimney.
CUPOLA– A decorative detail at the peak of a pitched roof sometimes used with ventilation or a lightening rod system.
CUPPING– When shingles are improperly installed over an existing roof or are over-exposed, they form a curl or cup.
CURB– A short wall or box built above the level of the roof to provide a means of flashing the deck equipment.
CUTBACK– Asphalt or tar that has been “cutback” with solvents and oils so that the material become fluid.
D
DAMPPROOFING– A process used on concrete, masonry or stone surfaces for the purpose of repelling water. Moisture vapor readily penetrates coatings of this type. The main purpose of dampproofing is to prevent the coated surface from absorbing rain water while allowing is to breathe moisture vapor out of the structure.
DEAD LOAD– The constant designed weight (of the roof) and any permanent fixtures attached above or below.
DECK– The base surface to which a roof system is applied.
DECKING– The structural “skin” of a roof over which roofing in applied. Most new homes have decking made of plywood. There are four main types of decking commonly used on residential roofing projects-
PLYWOOD– Plywood is strong, durable, and light. It comes in many grades with ratings from A to D. Use only exterior grade plywood for decking. The thickness of plywood depends on the spacing of the rafters.
OSB– Oriented strand board (OSB) is cheaper than plywood, but not as strong as plywood, and does not hold nails as well as plywood. One side has a slip resistant coating and should be placed facing up.
TONGUE AND GROOVE 2×6– If a roof will be seen from the inside (no ceiling installed), tongue and groove is used. It is a wood decking that provides great insulation without additional rigid roof insulation in moderate climates. Also, the boards can be painted or stained on the inside to match the interior.
STEP SHEATHING– Step sheathing is used alone or in combinations with solid sheathing for installation of tiles or shakes. Step sheathing allows air circulations under the tiles by using 1-by-6 or 2-by-6 boards that are evenly spaced so that air can move under the tiles or shakes.
DEFLECT– To bend or deform under weight.
DEW POINT– The critical temperature at which vapor condenses from the atmosphere and forms water.
DIFFUSION– The movement of a substance such as water vapor from regions of high concentration to regions of lower concentration
DIMENSIONAL SHINGLE– 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 together.
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.
DORMER– Structure which projects from a sloping roof.
DOUBLE TEE– Refers usually to a pre-cast roof deck panel poured with two fins in its underside to impart flexural rigidity.
DOWNSPOUT– The metal pipe used to drain water from a roof.
DRAWING OUTLINE– A top view drawing, of a building or roof showing only the perimeter drawn to scale.
DRAIN– a device used to carry water off of a roof.
DRAWING DETAIL– A top view drawing, of a building or roof showing the roof perimeter and indicating the projections and roof mounted equipment, drawn to scale.
DRIP EDGE- A device designed to prevent water from running back or under an overhang.
DRIPPAGE– Bitumen material that drips through roof deck joints, or over the edge of a roof deck.
DRY-IN– The process of installing the underlayment in steep slope roofing; Or making a low-slope roof watertight. Does not always mean getting all of the required plies installed.
DRY LAP– A term describing the absence of bitumen between the plies of felt at the overlap in a BURM.
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.
DRY SHEET- A ply mechanically attached to wood or gypsum decks to prevent asphalt or pitch from penetrating the deck and leaking into the building below.
DUCT– A cylindrical or rectangular “tube” used to move air either from exhaust or intake. The installation is referred to as “duct work”.
DUTCH LAP METHOD– Application of giant individual shingles with the long dimension parallel to the eaves. Shingles are applied to overlap adjacent shingles in each course as well as the course below.
DYNAMIC LOAD– Any moving load on a roof such as people and equipment. Wind can also be considered a Dynamic Load.
E
EAVE– A roof edge that extends out past the exterior wall line.
EDGE STRIPPING- Roofing material used to seal perimeter edge metal and the roof itself.
EDGE VENTING– 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.
EFFLORESCENCE– The process by which water leeches soluble salts out of concrete or mortar and deposits them on the surface. Also used as the name for these deposits.
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.
EMBEDMENT– In roofing, to uniformly press one material into another, such as aggregate into bitumen, roofing felt into bitumen, or granules into a coating.
EMULSION– Fine particles suspended in a liquid solution.
EPDM– Ethylene Propylene Diene Monomer. A single ply membrane consisting of synthetic rubber; usually 45 or 60 mils. Application can be ballasted, fully adhered or mechanically attached.
END LAP– The amount or location of overlap at the end of a roll of roofing felts in the application.
E.V.T. EQUI-VISCOUS TEMPERATURE– The critical temperature at which asphalt reaches the viscosity most favorable to good adhesion when applied in a BUR.
EXHAUST VENT– 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 COEFFICIENT– The amount that a specific material will vary in any one dimension with a change of temperature.
EXPANSION CLEAT– A cleat designed to handle thermal movement of the metal roof panels.
EXPANSION JOINT– A device used to make up the motion of expansion and contraction. On large roofs this provision for the movement of the materials forming the walls, roof deck and roof covering is usually made by deliberately separating the building into sections, and covering separation between adjacent sections with the expansion joint to allow movement but keep out the weather. Expansion joints, unlike control joints, penetrate through the roof deck.
EXPOSURE– The portion of a material (shingle or membrane) that is not overlapped by the succeeding ply or course.
EXTRUSION– An item formed by forcing a base metal (frequently aluminum) or plastic, at a malleable temperature, through a die to achieve a desired shape.
EYEBROW– A flat, normally concrete, projection which protrudes horizontally from a building wall; Eyebrows are generally located above windows.
F
FASADE– The front of a building. Frequently, in architectural terms an artificial or decorative effort.
FACTORY MUTUAL FM– A major insurance agency who has established stringent guidelines for maximum construction integrity as it relates to fire and environmental hazards. Their specifications have become industry standards.
FACTORY SEAM– A splice/seam made in the roofing material by the manufacturer. It is preferable during installation to remove these splices from the roof system. If a splice occurs on a shingle, it should be thrown away.
FASCIA– Any cover board at the edge or eaves of a flat, sloping, or overhanging roof which is placed in a vertical position to protect the edge of the roof assembly.
FASTENERS– A general term covering a wide variety of screws and nails that may be used for mechanically securing various components of a building.
FHA-The Federal Housing Authority. Sets construction standards
throughout the U.S.FELT– A very general term used to describe composition of roofing ply sheets, consisting of a mat of organic or inorganic fibers unsaturated, impregnated with asphalt or coal tar pitch, or impregnated and coated with asphalt.
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.
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.
FIRE WALL– Any wall built for the purpose of restricting or preventing the spread of fire in a building. Such walls of solid masonry or concrete generally sub-divided a building from the foundations to two or more feet above the plane of the roof.
FISHMOUTH– A characteristic opening at the exposed lap edge of BUR felts due to loss of bond or wrinkling of the felt.
FLAKE– A scale like particle. To lose bond from a surface in small thin pieces. Sometimes a paint film “flakes”.
FLANGE– 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.
FLASHING– Connecting devices that seal membrane joints at expansion joints, walls, drains, gravel stops, and other places where the membrane is interrupted or terminated.
FLASHING BASE– The upturned edge of the watertight membrane formed at a roof termination point by the extension of the felts vertically over the cant strip and up the wall for a varying distance where they are secured with mechanical fasteners.
FLASHING CEMENT– A trowelable mixture of solvent-based bitumen and mineral stabilizers.
FLASHING COLLAR– A flashing component used to seal soil pipe vents, hot stacks or other roof penetrations.
FLASHING, COUNTER– The formed metal secured to a wall, curb, or roof top unit to cover and protect the upper edge of a base flashing and it’s associated fasteners.
FLASH POINT– The critical temperature at which a material will ignite.
FLASHING, THRU-WALL– Flashing extended completely through a masonry wall. Designed and applied in combination with counter flashings to prevent water which may enter the wall above from proceeding downward in the wall or into the roof deck or roofing system.
FLAT SEAM– A seam at the junction of sheet metal roof components that has been bent at the plane of the roof.
FLOOD COAT– 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).
FLOP– Cutting of felts into strips, coating the deck side with bitumen and placing (flopping) the felt onto the deck.
FLASHING, STEP– Individual small pieces of metal flashing material used to flash around chimneys, dormers, and such projections along the slope of a roof. The individual pieces are overlapped and stepped up the vertical surface.
FOLDED SEAM– In sheet metal work, a joint between sheets of metal wherein the edges of the sheets are crimped together and folded flat.
FULLY ADHERED– A completely attached (adhered) roof membrane.
G
GABLE– The end of a building as distinguished from the front or rear side. The triangular end of and exterior wall from the level of the eaves to the ridge of a double-sloped roof.
GABLE ROOF– A roof configuration that has gable ends.
GAMBREL ROOF– A type of roof which has its slope broken by an obtuse angle, so that the lower slope is steeper than the upper slope. A double sloped roof having two pitches.
GALVANIC ACTION– A reaction between different metals in the presence of an electrolyte.
GALVANIZE– To coat a metal with zinc by dipping in molten zinc after cleaning.
GAUGE– The thickness of sheet metal and wire, etc.
GLASS FELT– In the manufacturing of roofing materials – a sheet comprised of bonded glass fibers prior to being saturated with bitumen.
GLAZE COAT– A light, uniform mopping of bitumen on exposed felts to protect them from the weather, pending completion of the job.
GRANULES– Mineral particles of a graded size which are embedded in the asphalt coating of shingles and roofing.
GRAVEL– Loose fragments of rock used for surfacing built-up roofs, in sizes varying from 1/8″ to 1 3/4″.
GRAVEL STOP– A flanged, sheet metal edge flashing with an upward projection installed along the perimeter of a roof to stop the flow of bitumen over the edge.
GROUT– A cement mortar mixture commonly used to fill joints and cavities of masonry. On roof decks, the joints between many types of precast roof deck slabs are grouted with cement grout.
GUTTER– Metal trough at the eaves of a roof to carry rainwater from the roof to the downspout.
GUTTER STRAP– Metal bands used to support the gutter.
GUY WIRE– A strong steel wire or cable strung from an anchor on the roof to any tall slender projection for the purpose of support.
GYPSUM– A hydrated sulfate of calcium occurring naturally in sedimentary rock. In roofing, a type of lightweight deck made from this pulverized rock.
H
HATCH– An opening in a deck; floor or roof. The usual purpose is to provide access from inside the building.
HEAT SEAMING– Fusing the seams of separate sections of roofing material together through the use of hot air or an open flame and pressure.
HEAT TRANSFER– Thermal energy going from an area of higher temperature to an area of lower temperature by conduction, convection, or radiation.
HEM– The edge created by folding metal back on itself. Metal is hemmed for safety and strength reasons.
HEX SHINGLES– Shingles that have the appearance of a hexagon after installation.
HIP– The angle formed by the intersection of two sloping roof planes.
HIP ROOF– A roof which rises by inclining planes from all four sides.
HIGH NAILING– When shingles are nailed or fastened above the
manufacturer’s specified nail location.“HOT”– Slang for hot bitumen.
I
ICE DAM– 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 overhang.
ICE AND WATER SHIELD (Leak Guard)– Composite materials of asphalt polymers in a self-adhered roll used in roofing as underlayment to prevent problems associated with ice-dams and high water flow areas.
IMPACT RESISTANCE- A roof assembly’s ability to withstand the impact from falling objects such as hail.
INFRARED THERMOGRAPHY– The use of an infrared camera to detect moisture in roof insulation.
INCOMPATIBILITY– Descriptive of two or more materials which are not suitable to be used together.
INSIDE DRAIN– A roof drain positioned on a roof at some location other than the perimeter. It drains surface water inside the building through closed pipes to a drainage system.
INSULATION– Material which slows down or retards the flow or transfer of heat.
INSULATION FASTENERS– Any of several specialized mechanical fasteners designed to hold insulation down to a steel or a nailable deck.
INSULATION VENT– A vent placed into the insulation which extends above the roof surface.
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.
INTERLAYMENT– 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.
IRMA– Insulated (or Inverted) Roof Membrane Assembly. In this system the roof membrane is laid directly on the roof deck, covered with extruded foam insulation and ballasted with stone, minimum of 1000 lbs. per square.
J
JOIST– Horizontally placed timber or beam set on edge to give support to a floor or ceiling.
K
KETTLE– Equipment used for heating bitumen to a flowing consistency.
L
LADDER, FIXED– A ladder which is permanently attached to a building.
LAP– To overlap or extend one material partially over another.
LEAD– A malleable metal once extensively used for flashings.
LEAN-TO ROOF– The sloping roof of a building addition having its rafters or supports pitched against and supported by the adjoining wall of a building.
LIQUID-APPLIED MEMBRANE– Generally applied to cast-in-place concrete surfaces in one or more coats to provide fully-adhered waterproof membranes which conform to all contours.
LIVE LOAD– The weight superimposed by snow or water or other tangibles which lack permanency, not including the wind load, on a roof.
LOOSE LAID– A membrane “laid loosely”, i.e., not adhered, over a roof deck or BURM.
M
MANSARD ROOF– A roof which rises by inclined planes from all four sides of a building.
MASTIC– A heavy trowel applied bitumen used for flashings or patch work which remains elastic and pliable.
MELT POINT– The temperature at which the solid asphalt becomes a liquid.
MEMBRANE– A generic term relating to a variety of sheet goods used for certain built-up roofing repairs and application. Also used to describe the combination of felts and moppings of bitumen forming a single flexible unit and waterproofing system of a BUR.
METAL EDGE– Brake metal or metal extrusions which are secured at the perimeter of a roof to form a weathertight seal.
MIL THICKNESS– Measurement used to determine thickness of a coating. 1 mil = .001 inch (1/1000).
MILDEW– A superficial coating or discoloration of organic materials caused by fungi, especially under damp conditions.
MINERAL SPIRITS– A by-product of petroleum, clear in color, a solvent for asphaltic coatings.
MINERAL SURFACED– A heavy roofing felt that has very small granules embedded across its surface.
MITER– The joint made by two diagonally cut pieces put together.
MODIFIED BITUMEN– Bitumen modified by special processing, generally with the addition of SBS type rubber or atactic polypylenes (APP). Some are non-reinforced, while others are reinforced with polyester, polyvinyl acetate, fiberglass, polypropylene or aluminum foil.
MOISTURE RELIEF VENT– A vent installed through the roofing membrane to relieve moisture vapor pressure that has been trapped within the roofing system. Moisture relief vents are usually installed when a new roofing system is installed above an old, failed, system.
MOISTURE SCAN– 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.
MONITOR– A large structure rising above the surrounding roof planes, designed to give light and/or ventilation to the building interior.
MONITOR, SAW-TOOTH– A type of monitor characterized by sharp angled pitches and vertical sections, usually arranged in rows much like teeth of a saw.
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.
MOPPING– A layer of hot bitumen mopped between plies of roofing felt.
MOPPING, FULL– The application of bitumen by mopping in such a manner that the surface being mopped is entirely coated with a reasonably uniform coating.
MOPPING, SPOT– The procedure of applying hot bitumen in a random fashion of small daubs, as compared to full mopping.
MOPPING, SPRINKLE– A special application of installing insulation to the decks. It is done by dipping a roof mop into hot bitumen and sprinkling the material onto the deck.
MOPPING, STRIP– The application of bitumen in parallel bands.
MORTAR– Mixture of sand, mortar, limestone and water used in bonding a chimney’s bricks together.
MUD CRACKS– Cracks developing from the normal shrinkage of an emulsion coating when applied too heavily and not reinforced.
N
NAILER– A piece of lumber secured to non-nailable decks and walls by bolts or other means, which provides a suitable backing onto which roof components may be mechanically fastened.
NAIL-GUIDE LINE– Painted line on laminated shingles, to aid in the proper placement of fasteners.
NAIL-POP– When a nail is not fully driven, it sits up off the roof deck.
NEOPRENE– A synthetic rubber produced by polymerization of Chloroprene for use in liquid-applied and sheet-applied elastomeric roofing.
NESTING– Installing a second layer of shingles aligning courses with the original roof to avoid shingle cupping.
NET FREE VENT AREA (Net Free Air Flow)– The area permitting unrestricted airflow.
NIGHT SEAL– To temporarily seal the edge of a roof membrane in order to protect it from moisture entry. A.K.A. Night Tie-Off and Water Cut-Off.
NON-DESTRUCTIVE– A phrase describing a method of examining the interior of a component whereby no damage is done to the component itself.
NUCLEAR METER– A device used to detect moisture by measuring slowed, deflected neutrons.
NRCA– National Roofing Contractors Association.
O
OIL-CANNING– The term describing distortion of thin-gauge metal panels which are fastened in a manner restricting normal thermal movement.
OPEN VALLEY– A valley where both sides of the roof are trimmed back from the centerline to expose the valley flashing material beneath.
ORGANIC- A term designating any chemical compound which contains carbon and hydrogen.
ORGANIC FELT– An asphalt roofing base material manufactured from cellulose fibers. Organic felt has been modernly replaced with fiberglass felt.
ORGANIC MAT– Material made from recycled wood pulp and paper.
ORGANIC SHINGLE– An asphalt shingle reinforced with organic material manufactured from cellulose fibers.
OSB– Oriented Strand Board. A decking made from wood chips and
lamination glues.OVER-DRIVEN– The term used for fasteners driven through roofing material with too much force, breaking the material.
OVER-EXPOSED– Installing shingle courses higher than their intended
exposure.OVERHANG- That part of the roof structure which extends horizontally beyond the vertical plane of the exterior walls of a building.
OXIDIZE- To combine with oxygen in the air.
P
PARAPET WALL– A low wall around the perimeter of a roof deck.
PARGE COAT– A thin application of plaster for coating a wall.
PASS- The term used to describe the application of one layer of Spray Polyurethane Foam (SPF). The speed of a pass will determine foam thickness.
PASS LINE- The distinct line formed between two passes of SPF. This line is the top skin of the bottom pass of the SPF.
PAVER STONES– Usually pre-cast concrete slabs used to create a traffic surface.
PENETRATION– Any object that pierces the surface of the roof.
PENTHO– USE– A relatively small structure built above the plane of the roof.
PERLITE- An aggregate formed by heating and expanding siliceous volcanic glass. Perlite in a fluffy heat expanded form is used in lightweight insulating concrete, fire-resistant rigid insulation board (R = 2.78 per inch) and potting soil.
PERMEABILITY- The rate of flow of a liquid or gas through a porous material.
PHASE CONSTRUCTION– In roofing the practice of applying the felt plies of the built-up roofing membrane in two or more operations, separated by a delay of at least one day.
PHOTO-OXIDATION– Oxidation caused by rays of the sun.
PIPE BOOT– A prefabricated flashing piece used to flash around circular pipe penetrations. Also known as a Roof Jack.
PITCH– A term frequently used to designate coal tar pitch.
PITCH PAN OR POCKET– A bottomless metal box placed on the roof around irregular projections. These are subsequently filled with coal tar pitch or mastic to create a weather tight seal.
PLASTICIZERS– Material incorporated into rubber and plastic in order to increase their flexibility and workability.
PLASTIC CEMENT– A term used to describe Type I asphalt roof cement. Plastic cement should not be used on vertical surfaces.
PLY– A single course of roofing felts or reinforced membrane.
PLYWOOD– Wooden panels formed by gluing thin sheets of wood together, with the grain of adjacent layers arranged at right angles.
POINTING– The process where joints between masonry units, brick, etc., are filled with mortar.
PONDING– The accumulation of water at low-lying areas on a roof.
POLYMER– A substance consisting of large molecules which have been formed from smaller molecules of similar make-up.
POLYURETHANE– Any of various polymers with a urethane base.
PONDING– A condition where water stands on a roof for prolonged periods due to poor drainage and/or deflection of the deck.
POP RIVETS– Fasteners used to join pieces of metal that are installed by either compressed air assisted or hand operated guns. Unique in that they are installed from one side of the work.
POROSITY– The density of substance and its capacity to pass liquids.
POUR COAT– The top coating of bitumen on a built-up roof.
POWER VENTS– Electrically powered fans used to move air from attics and structures.
PRECAST– Concrete building components which are formed and cured at a factory and then transported to a work site for erection.
PREVAILING WIND– The most common direction of wind for a particular region.
PRIMER– A material of relatively thin consistency applied to a surface for the purpose of creating a more secure bonding surface.
PROJECTION– Any object or equipment which pierces the roof membrane.
PROTECTION BOARD– Heavy asphalt impregnated boards which are laid over bituminous coatings to protect against mechanical injury.
PUNCTURE RESISTANCE– The ability of a material to withstand being pierced by a sharp object.
PURLINS– A horizontal structural member spanning between beams or trusses to support a roof deck.
PVC– Polyvinyl Chloride.
Q
QUARTER SIZED– Term for the size of hand sealant dabs, size of a U.S. 25 piece.
R
R-VALUE– The measure of a material’s resistance to heat flow. The higher a material’s R-value, the more it insulates.
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.
RAGGLE BLOCK– A specially designed masonry block having a slot or opening into which the top edge of the roof flashing is inserted and anchored.
RAKE– The angle of slope of a roof rafter, or the inclined portion of a cornice.
REFLECTIVE- A term referring to a material that has a white or shiny metallic surface.
REGLET– A horizontal slot, formed or cut in a parapet or other masonry wall, into which the top edge of counterflashing can be inserted and anchored.
RE-IMPREGNATE– To replace oils and bitumen in the components of the solvent based BUR which through weathering and oxidation, have been lost.
RESIN– The “B” component in SPF that is mixed with the “A” component in order to form polyurethane. Resin contains a catalyst, fire retardants, a blowing agent, Polyol, and a surface active agent.
RIDGE– The line where two planes of roof intersect, forming the highest point on the roof that runs the entire length of the roof.
RIDGE CAP– Material applied over the ridge or hip of a roof.
RIDGE COURSE– The final course of roofing applied that covers the area where two or more roof planes intersect.
RIDGE VENT– An exhaust venting device located at the ridge of a roof that works in conjunction with a starter or under eave soffit vent and is used to ventilate attics. Ridge vents and their cooperative starter or soffit vents should be installed at a 1-1 ratio in order to function properly.
ROOF– The assembly of interacting components designed to weatherproof and normally to insulate a buildings surface, separated from adjacent assemblies by walls or changes in elevation.
ROOF COATING– A bituminous material, either a cutback or an emulsion, to protect the surface of the BUR but not necessarily to re-impregnate it.
ROOF DECK– That component in building construction, which forms a platform on which the remainder of the BUR components are placed.
ROOF DRAIN– The termination or fitting at the roof of an interior drain or leader, for draining rain water from nominally flat roofs.
ROOF LOUVERS– Rooftop rectangular shaped roof vents. Also called box vents, mushroom vents, airhawks, soldier vents.
ROOF PLANE– A roofing area defined by having four separate edges. One side of a gable, hip or mansard roof.
ROOF SEAMER– A mechanical device used to crimp metal roof panels and make the seams watertight, OR a machine used to weld membrane laps of PVC (Thermoplastic) roofing material.
ROOF SLOPE– The angle made by the roof surface plane with the horizontal plane and expressed as the amount of vertical rise for every twelve inch (12″) horizontal run. For instance, a roof that rises four inches (4″) for every twelve inch (12″) horizontal run, is expressed as having a “four in twelve” slope; often written as “4-12.” Expressed as a percentage, the slope would be 33%, which is equal to 4 divided by 12. Also known as the Pitch of a roof.
ROOF SYSTEM– General term referring to the waterproof covering, roof insulation, vapor barrier, if used and roof deck as an entity.
RUN– The horizontal distance between the eaves and the ridge of the roof, being half the span for a symmetrical gable roof.
S
SADDLE– A ridge in the roof deck, whose top divides two sloping parts of the roof so that water will be diverted to the roof drains.
SATURATED FELT- Felt that has been saturated with bitumen.
SAW TOOTH ROOF– Where reviewed from the end, such a roof serrated or tooth profile similar to the teeth of a saw.
SCRIM– A woven or mat-type fabric that is used as a membrane sandwich between other material to provide reinforcement and stretch resistance.
SCUPPER– An outlet in the wall of a building or a parapet wall for drainage of water from a flat roof.
SEALANT- Generic term for a multitude of materials used to seal joints or junctures against moisture or weather.
SELF-HEALING– A term used in reference to a material which melts with the heat from the sun’s rays, and seals over cracks that were earlier formed from other causes.
SELF-LEVELING– A viscous material that is applied by pouring. In its uncured state, it spreads out evenly.
SELVAGE– The unsurfaced strip along a sheet of roll roofing which forms the under portion at the lap in the application of the roof covering.
SHED ROOF- A roof having only one slope or pitch, with only one set of rafters which fall from a higher to a lower wall.
SHEATHING– The boards of sheet type material, plywood or asphalt saturated sheets, nailed to studding or roofing rafters as the base for application of the roof covering.
SHINGLE-FASHION– The pattern formed by laying parallel felt rolls with lapped joints so that one longitudinal edge overlaps the longitudinal edge on the adjacent felts. Shingle fashion application begin at the low point on a roof so that one ply drains water to a lower one and so on to a drain or to the roof edge.
SHINGLES– Small units of material which are laid in a series of overlapping rows as a roof covering on pitched roofs.
SHINGLE WARRANTY– Shingle warranties are often confused with “system warranties.” Shingle warranties are prorated, and usually carry a very small value after the first 5 years of shingle life. In other words, the warranty that comes with shingles is designed to never be redeemed for new shingles or labor.
SIGN ANCHOR– A component usually formed with steel angles which penetrates the BUR and is fastened to the deck.
SINGLE PLY– A descriptive term signifying a roof membrane composed of only one layer of material such as EPDM, TPO or PVC.
SINGLE TEE– The name given to a type of precast concrete deck which has one stiffening rib integrally cast into slab.
SITE– The physical grouping of a number of roofs or buildings at a geographical location.
SKY DOME– A type of skylite exhibiting a characteristic translucent plastic domed top.
SKYLIGHT– A structure on a roof that is designed to admit light and is somewhat above the plane of the roof surface.
SLAG– A by-product of smelting ore such as iron, lead or copper.
SLATE– A dark gray stratified stone cut relatively thin and installed on pitched roofs in a shingle like fashion.
SLIPPAGE– It is the sliding, lateral movement between adjacent to plies of felt along the plane of the bitumen film separating them, which results in a randomly wrinkled appearance.
SLOPE– Incline or pitch of roof surface.
SOFFIT– The underside of a part or member of a building extending out from the plane of the building walls.
SOFTENING POINT- The temperature at which a substance changes from a hard material to a softer and more viscous material.
SMOOTH SURFACE TEXTURE– In SPF roofing, a relatively smooth surfaced texture that is considered ideal for receiving the base coating.
SMOOTH-SURFACED ROOF- A roof with no surfacing or with a smooth surfacing such as emulsion and/or a reflective coating.
SNOW GUARD– Devices secured to the roof to prevent snow and ice from sliding off of a roof.
SNOW LOAD– A roof load resulting from snowfall. Snow load is a major structural consideration when roofs are designed in areas that receive heavy snow.
SOFFIT– The underside of a roof overhang.
SOFFIT VENT- An intake ventilation device located in the soffit. An exhaust vent should be installed on or near the ridge of the roof to work in conjunction with the soffit vent in order to properly ventilate the attic space. The ratio of intake vent area to exhaust vent area should be 1-1.
SOFTENING POINT- The temperature at which bitumen will begin to flow.
SOFTENING POINT DRIFT– A change in the softening point of bitumen.
SOIL STACK- A pipe that penetrates a roof and is used to vent a building’s plumbing.
SOLID MOPPING– To continuously apply hot asphalt or coal tar leaving no areas without bitumen.
SOLVENT– A liquid that is part of a substance and is used to make that substance easier to work with. Once applied, the solvent evaporates and leaves the working characteristics of the substance. Examples are solvent-based adhesives and solvent-based mastics.
SOLVENT WELD– To weld materials using a liquid solvent.
SPALLING– The chipping or flaking of concrete, bricks, or other masonry where improper drainage or venting and freeze/thaw cycling exists.
SPAN- The horizontal distance between supporting structures such as beams, trusses or columns.
SPECIFICATION– Detailed written instructions which, when clear and concise, explain each phase of work to be done.
SPLITTING– The formation of long cracks completely through a roof membrane. Splits are frequently associated with lack of allowance for expansion stresses. They can also be a result of deck deflection or change in deck direction.
SPRAYED POLYURETHANE FOAM (SPF)– A monolithic sprayed-on roofing material with a high R-value; formed when isocyanate (“A” component) and resin (“B” component) are mixed at a 1-1 ratio.
SPRI- Single Ply Roofing Institute
SQUARE– A term used by the roof industry to indicate an amount of roof area equal to 100 square feet.
SPUD– The removal of gravel or heavy accumulations of bitumen from roof membranes by means of chipping or scraping
STACK– A vertical pipe projecting through a BUR that carries off smoke or gases.
STACK EFFECT- The occurrence where air escapes through opening in the upper part of a building and is replaced with outside air that enters through an opening lower down. In roofing, the Stack Effect helps create proper airflow for attic or roof space ventilation. The Stack Effect will be affected by atmospheric conditions such as temperature and wind.
STANDING SEAM– A type of joint often used on metal roofs.
STARTER STRIPS– In the construction of the BUR the narrow strips of roofing felts, cut from standard width rolls, that are applied at the beginning point so as to assure uniform configuration of the specified number of plies.
STATIC LOAD– In roofing the total amount of permanent non moving weight that is applied to given surface areas.
STEEP SLOPE ROOFING– Generally all slopes higher than 4/12 are considered steep slopes.
STEP-FLASHING– Metal flashing pieces installed at side-walls and chimneys for weather-proofing.
STYRENE– A colorless oily liquid, C6H5CH-CH2, the monomer for polystyrene.
STYRENE BUTADIENE STYRENE (SBS)- The modifying agent used in SBS modified asphalt roofing materials that gives the material a rubber like quality. SUBSTRATE A part or substance which lies below and supports another.
SUMP– A reservoir sometimes forming part of a roof drain. A depression in the roof deck of a building at a roof and delivery it to the drain.
SURFACE EROSION– The effect on a surface after being worn away from abrasion or weathering.
SURFACE TEXTURE– The final appearance and quality of an SPF surface. SPF surface textures will be one of the following- Orange Peel Surface Texture, Coarse Orange Peel Surface Texture, Smooth Surface Texture, Verge of Popcorn Surface Texture, Popcorn Surface Texture, and Tree-Bark Surfaced Texture.
SYSTEM WARRANTY– (see “Shingle Warranty”) A warranty that comes with an entire roofing system installation. For instance, some shingle manufacturers offer very strong, long-term system warranties if the laborers are manufacturer-trained and if all portions of installation adhere directly to manufacturer’s specifications. This system warranty has massive value in relation to the standard shingle warranty.
SURFACING– The top-most layer of the roof system designed to protect the system from damage.
T
TAB– The portion of an asphalt shingle that is outlined by the cutouts.
TAR– A brown or black bituminous material, liquid or semi-solid in consistency, in which the predominating constituents are bitumens obtained as condensates in the processing of coal, petroleum, oil-shale, wood, or other organic materials.
TAR BOIL- A small bubble found in the flood coat of an aggregate-surfaced built-up roof; usually the result of trapped moisture vapor.
TEAR OFF– A term used to describe the complete removal of the roof membrane and insulation down to and exposing the roof deck.
TELEGRAPHING- When shingles reflect the uneven surface beneath them. Shingles installed over buckled shingles may show some buckles.
TENSILE STRENGTH- The amount of longitudinal pulling stress that a material can withstand before being pulled apart.
TERMINATION– The sealed edges of a roof membrane.
TERMINATION BAR- A bar, usually metal or vinyl, used to seal and anchor the free edges of a roof membrane.
THATCH ROOF– A roof covering made with straw, palms, reeds or other natural growths that are bound together in order to shed water.
THERMAL RESISTANCE (R)- The measure of a material’s ability to resist heat flow. The formula for Thermal Resistance is R = L / k where (L) is the material’s thickness and (k) is the material’s Thermal Conductivity constant. The higher a material’s R-value, the better it insulates, and conversely. For more information, click here.
THERMAL MOVEMENT- The measured amount of dimensional change, a material exhibits as it is warmed or cooled.
THERMAL SHOCK– The stress built up by sudden and appreciable changes in temperature.
THERMAL STRESS– Stress to a roof system or component caused by expansion and / or contraction from temperature change.
THERMOPLASTIC MATERIAL– Solid material which is softened by increasing temperatures and hardened by decreasing temperatures.
TIE-IN– A term used to describe the joining of a new roof with the old.
TIE-OFF– A watertight seal used to terminate roof membranes at system adjuncts, terminations, flashings, or substrates. Can be temporary (see Night Seal) or permanent.
TILT-UP WALL– Cast concrete units which are preformed which, when cured, are tilted to their vertical position and secured by mechanical fasteners to prior erected structural steel. May be pre-cast.
TOP MOPPING– The finished mopping of hot bitumen on a built-up roof.
TORCHING– Applying direct flame to a membrane for the purpose of melting, heating or adhering.
TREEBARK SURFACE TEXTURE– An SPF surface deemed unacceptable for coating. This surface texture has deep valleys and is similar in appearance to rough tree bark.
TRUSS– A major supporting structure usually timber for roof decks.
TUCK POINTING– The re-grouting of defective mortar joints in a masonry or brick wall.
U
ULTRAVIOLET LIGHT (UV)– A form of luminous energy occupying a position in the spectrum of sunlight beyond the violet, and having wavelengths that do not enter the visible spectrum. UV rays accelerate deterioration of roof materials.
UNDER-DRIVEN– Term used to describe a fastener not fully driven flush to the shingles surface.
UNDERLAYMENT- A material installed over the roof deck prior to the application of the primary roof covering. Usually consists of fifteen (15#) or thirty (30#) pound organic felt but can also be self-adhering such as an ice and water protection membrane.
UNDERWRITERS LABORATORIES (UL)– A non-profit agency which functions as the testing arm of the National Board of Fire Underwriters. It maintains laboratories for the examination and testing of various devices, systems, and materials to determine their safety against the hazards of fire, wind, and accidents.
V
VALLEY– A term applied to a depressed angle formed by the meeting of two inclined slopes of a roof.
VAPOR– The gaseous form of any substance.
VAPOR MIGRATION– The natural movement of water vapor from regions of higher vapor pressure to regions of lower vapor pressure.
VAPOR PRESSURE– The pressure at which a liquid and its vapor are in equilibrium at a definite temperature.
VAPOR RETARDER- A material used to restrict the passage of water vapor through a roof assembly.
VEINING– The characteristic lines or “stretch marks” which develop during the aging process of soft bitumens. Veneer- Any of the thin layers of wood glued together to make plywood.
VENT– An opening or device used to permit air or vapors to exit an enclosed structure.
VENT PIPE– A vertical pipe of relatively small dimensions which protrudes through a roof to provide for the ventilation of gasses.
VENTILATION SHORT CIRCUIT- The disruption of air flow in an intake-exhaust ventilation system. For instance, if vents such as turbine vents or gable vents are placed in between the intake vents and exhaust vents (such as soffit and ridge vents) then the draw created by the stack effect will be disrupted and the ventilation system will be much less effective.
VENTILATOR– Device installed on the roof for the purpose of ventilating the interior of the building.
VENTING– The process of installing roof vents in a roof assembly to relieve vapor pressure, OR the process of water in the insulation course of the roof assembly evaporating and exiting via the roof vents.
VERMICULITE- An aggregate somewhat similar to perlite that is used as an aggregate in lightweight roof decks and deck fills. It is formed from mica, a hydrous silicate.
VERTICAL APPLICATION– Roll roofing laid parallel to the slope of a roof.
VISCOSITY– The internal frictional resistance offered by a fluid to change of shape or to the relative motion or flow of its parts.
VULCANIZE- To improve the strength, resiliency, and freedom from stickiness and odor of rubber, for example, by combining with sulfur or other additives in the presence of heat and pressure.
W
WALKWAYS– Designated areas for foot traffic on roofs.
WATER ABSORPTION- The increase in weight of a test specimen expressed as a percentage of its dry weight after being immersed in water for a specified time at a given temperature.
WATER GUARD– A turned up edge on valley metal or continuous wall flashing; used to prevent water migration under the roof system.
WARM WALL- The finished wall inside of a structure, used in roofing to determine how to install waterproof underlayments at eaves.
WARRANTY- The written promise to the owner of roofing materials for material related problems.
WATER STOP– A device designed to protect the exposed edge of a partially installed BURM from water entrance.
WATERPROOFING- The process where a building component is made totally resistant to the passage of water and/or water vapor.
WATER VAPOR- Moisture existing as a gas in air.
WEEP HOLE- A hole that allows for drainage of entrapped water from masonry structures.
WELD– The joining of components together by fusing. In thermoplastics, refers to bonding together of the membrane using heat or solvents.
WIND UPLIFT– The upward force exerted by wind traveling across a roof.
WRINKLE- A raised pattern of ridges running in a random fashion in a BUR.
X
Y
Z
ZINC– A bluish-white, lustrous metallic element that is brittle at room temperature but malleable with heating. It is used to form a wide variety of alloys including brass, bronze, various solders, and nickel silver, in galvanizing iron and other metals, for electric fuses, anodes, and meter cases, and in roofing, gutters, flashings, edge metals and also for various household objects. Atomic number 30; atomic weight 65.37; melting point 419.4 C; boiling point 907 C; specific gravity 7.133 (25 C); valence 2.
ZONOLITE– A lightweight, insulating concrete composed of portland cement, water, and vermiculite aggregate.
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