Roofing Terms Glossary
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Crushed stone, slag or water-worn gravel
that comes in a wide range of sizes. Used to surface built-up roofs.
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.
A dark brown to black, highly viscous,
hydrocarbon produces from the residue left after the distillation of petroleum, used
as a waterproofing agent.
Weight used to protect single-ply roofs or
to prevent blow off of systems which are not adhered.
The practice of nailing roofing felts to
the deck under the overlap, in addition to hot mopping, to prevent slippage of felts.
Small areas on a roof where the top
membrane has become exposed to the
A roof design which in cross section is
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
a formed piece of metal designed to cover
the joint between two lengths of metal
Any of various mixtures of hydrocarbons
occurring naturally or obtained through the distillation of coal or petroleum. (See
Coat Tar Pitch and Asphalt).
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.
A semi-rounded strip (bead) of caulking
A heavy main support structure, steel or
wood running horizontally between columns or load bearing walls.
A substance or a tape applied between two
adjoining materials to prevent adhesion between them.
Sheet metal that has been bent to the
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.
A specialized steel reinforcing member
which support form boards and reinforces a gypsum deck, which when poured surrounds
A roof assembly which pitches sharply from
either side toward the center.
An overhanging roof.
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.
One to four plies of felt bonded and top
coated with bitumen that is laid over an existing roof as a treatment for defective
A general term for a variety of trowelable
mastics, asphalt or tar, which are used during roof construction and repair.
The resulting dust which occurs on a
surface that is susceptible to Ultra Violet degradation.
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.
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
A layer of any brush consistency product
spread over a surface for protection.
Products that can be applied without
heating. These are in contrast to tar or asphalt which need to be heated to be
A roof repair done with cold applied
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.
Two or more substances which can be mixed
or blended without separating, reacting, or affecting either material
Any one part of an assembly associated
An insulation board which has two
different insulation types laminated together in 2 or 3 layers.
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.
A large device mounted on roofs,
consisting of many baffles over which water is pumped in order to reduce its temperature.
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
A horizontal projecting course on the
exterior of a building, usually at the base of the parapet.
The deterioration of metal by chemical or
electrochemical reaction resulting from exposure to weathering, moisture,
chemicals or other agents or media.
A control joint controls or accommodates
movement in the surface component of a roof.
A construction unit placed at the top of
the parapet wall to serve as a cover for the wall.
Folded or shaped into parallel ridges or
furrows so as to form a symmetrically wavy surface.
A single layer of brick or stone or other
A series of hairline cracks in the surface
of weathered materials, having a web-like appearance.
The evaluation of a part of a roof surface
as a means of promoting drainage of water from behind an obstacle such as
A small monitor or dome at the peak of a
A short wall or masonry built above the
level of the roof. It provides a means of flashing the deck equipment.
Basic asphalt or tar which has been
"cutback" with solvents and oils so that the material become fluid.
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.
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.
The constant designed weight (of the roof)
and any permanent fixtures attached above or below.
The base surface to which a roof system is
To bend or deform under weight.
The critical temperature at which vapor
condenses from the atmosphere and forms water.
The house-like structure which projects
from a sloping roof.
Refers usually to a precast roof deck
panel poured with two fins in its underside to impart flexural rigidity.
The metal pipe used to drain water from a
A top view drawing, of a building or roof
showing only the perimeter drawn to scale.
A top view drawing, of a building or roof
showing the roof perimeter and indicating the projections and roof mounted
equipment, drawn to scale.
A device designed to prevent water from
running back or under an overhang.
Bitumen material that drips through roof
deck joints, or over the edge of a roof deck.
A term describing the absence of bitumen
between the plies of felt at the overlap in a BURM.
A ply mechanically attached to wood or
gypsum decks to prevent asphalt or pitch from penetrating the deck and leaking into
the building below.
A cylindrical or rectangular "tube" used
to move air either from exhaust or intake. The installation is referred to as "duct
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.
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.
A term relating to brake or extruded metal
around the perimeter of a roof.
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.
A general term, any of the numerous
flexible roof membranes that contain rubber or plastic.
In roofing, a coating consisting of
asphalt and fillers suspended in water.
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.
The amount that a specific material will
vary in any one dimension with a change of temperature.
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.
An item formed by forcing a base metal
(frequently aluminum) or plastic, at a malleable temperature, through a die to
achieve a desired shape.
A flat, normally concrete, projection
which protrudes horizontally from a building wall; Eyebrows are generally located above
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.
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.
A general term covering a wide variety of
screws and nails which may be used for mechanically securing various components
of a building.
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
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.
A characteristic opening at the exposed
lap edge of BUR felts due to loss of bond or wrinkling of the felt.
A scale like particle. To lose bond from a
surface in small thin pieces. Sometimes a paint film "flakes".
Connecting devices that seal membrane
joints at expansion joints, walls, drains, gravel stops, and other places where the membrane
is interrupted or terminated.
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.
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
The critical temperature at which a
material will ignite.
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.
In sheet metal work, a joint between
sheets of metal wherein the edges of the sheets are crimped together and folded
A seam at the junction of sheet metal roof
components that has been bent at the plane of the roof.
Cutting of felts into strips, coating the
deck side with bitumen and placing (flopping) the felt onto the deck.
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
A completely attached (adhered) roof
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.
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.
To coat a metal with zinc by dipping in
molten zinc after cleaning.
The thickness of sheet metal and wire,
A light, uniform mopping of bitumen on
exposed felts to protect them from the weather, pending completion of the job.
The mineral particles of a graded size
which are embedded in the asphalt coating of shingles and roofing.
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.
Metal trough at the eaves of a roof to
carry rain water from the roof to the downspout.
Metal bands used to support the gutter.
A strong steel wire or cable strung from
an anchor on the roof to any tall slender projection for the purpose of support.
A hydrated sulfate of calcium occurring
naturally in sedimentary rock. In roofing, a type of lightweight deck made from this
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