ROOFING

AGGREGATE
Crushed stone, slag or water-worn gravel that comes in a wide range of sizes. Used to surface built-up roofs.

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.

BALLAST
Weight used to protect single-ply roofs or to prevent blow off of systems which are not adhered.

BACK NAILING
The practice of nailing roofing felts to the deck under the overlap, in addition to hot mopping, to prevent slippage of felts.

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 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.

a formed piece of metal designed to cover the joint between two lengths of metal
edge.

Any of various mixtures of hydrocarbons occurring naturally or obtained through the distillation of coal or petroleum. (See Coat Tar Pitch and Asphalt).

BLISTER
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.

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.

BUILT-UP ROOF – BUR
A roof consisting minimally of a BUR membrane but may also include insulation, vapor retarders and other components.

BUILT-UP ROOF MEMBRANE – BURM

A built-up roof consisting of plies or layers of roofing felt bonded together on site with bitumen; either tar or asphalt.

BULB-TEE
A specialized steel reinforcing member which support form boards and reinforces a gypsum deck, which when poured surrounds the Bulb-Tee.

BUTTERFLY ROOF
A roof assembly which pitches sharply from either side toward the center.

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 SHEETS
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.

CEMENT, ROOFING
A general term for a variety of trowelable mastics, asphalt or tar, which are used during roof construction and repair.

CHALK (ing)
The resulting dust which occurs on a surface that is susceptible to Ultra Violet degradation.

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.

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.

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.

COATING
A 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.

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.

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. A “core” is taken from the roof to verify the construction of the existing roof system. The deck is visible along with the insulation and the roof membrane. The core is then replaced and repaired immediately with the
appropriate mastic and Fiberglas reinforcing mesh.

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.

CORRUGATED
Folded or shaped into parallel ridges or furrows so as to form a symmetrically wavy surface.

COURSE
A single layer of brick or stone or other building material.

CRAZING
A series of hairline cracks in the surface of weathered materials, having a web-like appearance.

CRICKET
The evaluation of a part of a roof surface as a means of promoting drainage of water from behind an obstacle such as chimney.

CUPOLA
A small monitor or dome at the peak of a pitched roof.

CURB
A short wall or masonry built above the level of the roof. It provides a means of flashing the deck equipment.

CUTBACK

Basic asphalt or tar which has been “cutback” with solvents and oils so that the material become fluid.

CUT OFF
A piece of roofing membrane consisting of one or more narrow plies of felt usually moped in hot to seal the edge of insulation at the end of a day’s work.

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 damp proofing 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.

DEFLECT
To bend or deform under weight.

DEW POINT
The critical temperature at which vapor condenses from the atmosphere and forms water.

DORMER
The house-like structure which projects from a sloping roof.

DOUBLE TEE
Refers usually to a precast 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.

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 LAP
A term describing the absence of bitumen between the plies of felt at the overlap in a BURM.

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”.

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.

EAVE
The part of a roof which projects out from the side wall, or the lower edge of the part of a roof that overhangs a wall.

EDGE METAL
A term relating to brake or extruded metal around the perimeter of a roof.

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
A general term, any of the numerous flexible roof membranes that contain rubber or plastic.

EMULSION
In roofing, a coating consisting of asphalt and fillers suspended in water.

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.

EXPANSION COEFFICIENT
The amount that a specific material will vary in any one dimension with a change of temperature.

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.

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.

FACADE
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.

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 which may be used for mechanically securing various components of a building.

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.

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”.

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, 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 its 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 counterflashings, to prevent water which may enter the wall above from proceeding downward in the wall or into the roof deck or roofing system.

FOLDED SEAM
In sheet metal work, a joint between sheets of metal wherein the edges of the sheets are crimped together and folded flat.

FLAT SEAM
A seam at the junction of sheet metal roof components that has been bent at the plane of the roof.

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.

FULLY ADHERED
A completely attached (adhered) roof membrane.

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.

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.

GALVANIZE
To coat a metal with zinc by dipping in molten zinc after cleaning.

GAUGE
The thickness of sheet metal and wire, etc.

GLAZE COAT
A light, uniform mopping of bitumen on exposed felts to protect them from the weather, pending completion of the job.

GRANULES
The 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″.

GROUT OR GROUTING
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 rain water 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.

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