We at Cudahy Roofing feel strongly in our clients being able to make an educated decision when it comes to repairing or replacing their roof. The following is a comprehensive list of roofing terms posted for your knowledge and benefit.
Please vist our Home Page>
AGGREGATECrushed stone, slag or water-worn gravel that comes in a wide range of sizes.
Used to surface built-up roofs.
ALLIGATORINGA 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.
ASPHALTA dark brown to black, highly viscous, hydrocarbon produces from the residue left
after the distillation of petroleum, used as a waterproofing agent.
BALLASTWeight used to protect single-ply roofs or to prevent blow off of systems which are
BACK NAILINGThe practice of nailing roofing felts to the deck under the overlap, in addition to hot
mopping, to prevent slippage of felts.
BARE SPOTSSmall areas on a roof where the top membrane has become exposed to the
BARREL ROOFA roof design which in cross section is arched.
BASE PLYAn 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
BATTEN PLATEa formed piece of metal designed to cover the joint between two lengths of metal
BITUMENAny 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.
BEADA semi-rounded strip (bead) of caulking material.
BEAMA heavy main support structure, steel or wood running horizontally between
columns or load bearing walls.
BOND BREAKERA substance or a tape applied between two adjoining materials to prevent adhesion
BRAKE METALSheet metal that has been bent to the desired configuration.
BUILT-UP ROOF - BURA roof consisting minimally of a BUR membrane but may also include insulation, vapor
retarders and other components.
BUILT-UP ROOF MEMBRANE - BURMA built-up roof consisting of plies or layers of roofing felt bonded together on site
with bitumen; either tar or asphalt.
BULB-TEEA specialized steel reinforcing member which support form boards and reinforces
a gypsum deck, which when poured surrounds the Bulb-Tee.
BUTTERFLY ROOFA roof assembly which pitches sharply from either side toward the center.
CANOPYAn overhanging roof.
CANT STRIPA 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 SHEETSOne 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, ROOFINGA 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
CHECKINGA 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.
CLEATA 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
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.
COATINGA layer of any brush consistency product spread over a surface for protection.
COLD APPLIEDProducts that can be applied without heating. These are in contrast to tar or
asphalt which need to be heated to be applied.
COLD PATCHA roof repair done with cold applied material.
COLLARA 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.
COMPATIBLETwo or more substances which can be mixed or blended without separating,
reacting, or affecting either material adversely.
COMPONENTAny one part of an assembly associated with construction.
COMPOSITE BOARDAn insulation board which has two different insulation types laminated together in
2 or 3 layers.
CONDUCTORA 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 TOWERA large device mounted on roofs, consisting of many baffles over which water is
pumped in order to reduce its temperature.
COREA small section cut from any material to show internal composition. The core was
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 (see construction
section). The core was then replaced and repaired immediately with the
appropriate mastic and fiberglas reinforcing mesh.
CORNICEA horizontal projecting course on the exterior of a building, usually at the base of
CORROSIONThe deterioration of metal by chemical or electrochemical reaction resulting from
exposure to weathering, moisture, chemicals or other agents or media.
CONTROL JOINTA control joint controls or accommodates movement in the surface component of a
COPINGA construction unit placed at the top of the parapet wall to serve as a cover for the
CORRUGATEDFolded or shaped into parallel ridges or furrows so as to form a symmetrically wavy
COURSEA single layer of brick or stone or other building material.
CRAZINGA series of hairline cracks in the surface of weathered materials, having a web-like
CRICKETThe evaluation of a part of a roof surface as a means of promoting drainage of
water from behind an obstacle such as chimney.
CUPOLAA small monitor or dome at the peak of a pitched roof.
CURBA short wall or masonry built above the level of the roof. It provides a means of
flashing the deck equipment.
CUTBACKBasic asphalt or tar which has been "cutback" with solvents and oils so that the
material become fluid.
CUT OFFA 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.
DAVEThe name of the guy who compiled this glossary. I'm glad you are actually reading this.
DAMPPROOFINGA 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 LOADThe constant designed weight (of the roof) and any permanent fixtures attached
above or below.
DECKThe base surface to which a roof system is applied.
DEFLECTTo bend or deform under weight.
DEW POINTThe critical temperature at which vapor condenses from the atmosphere and forms
DORMERThe house-like structure which projects from a sloping roof.
DOUBLE TEERefers usually to a precast roof deck panel poured with two fins in its underside to
impart flexural rigidity.
DOWNSPOUTThe metal pipe used to drain water from a roof.
DRAWING OUTLINEA top view drawing, of a building or roof showing only the perimeter drawn to scale.
DRAWING DETAILA top view drawing, of a building or roof showing the roof perimeter and indicating
the projections and roof mounted equipment, drawn to scale.
DRIP EDGEA device designed to prevent water from running back or under an overhang.
DRIPPAGEBitumen material that drips through roof deck joints, or over the edge of a roof deck.
DRY LAPA term describing the absence of bitumen between the plies of felt at the overlap
in a BURM.
DRY SHEETA ply mechanically attached to wood or gypsum decks to prevent asphalt or pitch
from penetrating the deck and leaking into the building below.
DUCTA cylindrical or rectangular "tube" used to move air either from exhaust or intake.
The installation is referred to as "duct work".
EPDMEthylene Propylene Diene Monomer. A single ply membrane consistsing of
synthetic rubber; usually 45 or 60 mils. Application can be ballasted,
fully adhered or mechanically attached.
EAVEThe 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 METALA term relating to brake or extruded metal around the perimeter of a roof.
EFFLORESCENCEThe 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.
ELASTOMERICA general term, any of the numerous flexible roof membranes that contain rubber
EMULSIONIn roofing, a coating consisting of asphalt and fillers suspended in water.
END LAPThe amount or location of overlap at the end of a roll of roofing felts in the
E.V.T. EQUI-VISCOUS TEMPERATUREThe critical temperature at which asphalt reaches the viscosity most favorable to
good adhesion when applied in a BUR.
EXPANSION COEFFICIENTThe amount that a specific material will vary in any one dimension with a change
EXPANSION JOINTA 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.
EXTRUSIONAn item formed by forcing a base metal (frequently aluminum) or plastic, at a
malleable temperature, through a die to achieve a desired shape.
EYEBROWA flat, normally concrete, projection which protrudes horizontally from a building
wall; Eyebrows are generally located above windows.
FACADEThe front of a building. Frequently, in architectural terms an artificial or decorative
FACTORY MUTUAL FMA 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.
FASCIAAny 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.
FASTENERSA general term covering a wide variety of screws and nails which may be used for
mechanically securing various components of a building.
FELTA 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 WALLAny 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.
FISHMOUTHA characteristic opening at the exposed lap edge of BUR felts due to loss of bond
or wrinkling of the felt.
FLAKEA scale like particle. To lose bond from a surface in small thin pieces. Sometimes
a paint film "flakes".
FLASHINGConnecting devices that seal membrane joints at expansion joints, walls, drains, gravel
stops, and other places where the membrane is interrupted or terminated.
FLASHING BASEThe 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, COUNTERThe 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 POINTThe critical temperature at which a material will ignite.
FLASHING, THRU-WALLFlashing 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 SEAMIn sheet metal work, a joint between sheets of metal wherein the edges of the
sheets are crimped together and folded flat.
FLAT SEAMA seam at the junction of sheet metal roof components that has been bent at the
plane of the roof.
FLOPCutting of felts into strips, coating the deck side with bitumen and placing (flopping)
the felt onto the deck.
FLASHING, STEPIndividual 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 ADHEREDA completely attached (adhered) roof membrane.
GABLEThe 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
GAMBREL ROOFA 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.
GALVANIZETo coat a metal with zinc by dipping in molten zinc after cleaning.
GAUGEThe thickness of sheet metal and wire, etc.
GLAZE COATA light, uniform mopping of bitumen on exposed felts to protect them from the
weather, pending completion of the job.
GRANULESThe mineral particles of a graded size which are embedded in the asphalt coating
of shingles and roofing.
GRAVELLoose fragments of rock used for surfacing built-up roofs, in sizes varying from 1/8"
to 1 3/4".
GROUT OR GROUTINGA 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.
GUTTERMetal trough at the eaves of a roof to carry rain water from the roof to the
GUTTER STRAPMetal bands used to support the gutter.
GUY WIREA strong steel wire or cable strung from an anchor on the roof to any tall slender
projection for the purpose of support.
GYPSUMA hydrated sulfate of calcium occurring naturally in sedimentary rock. In roofing,
a type of lightweight deck made from this pulverized rock.
HATCHAn opening in a deck; floor or roof. The usual purpose is to provide access from
inside the building.
HIP ROOFA roof which rises by inclining planes from all four sides of a building.
INCOMPATIBILITYDescriptive of two or more materials which are not suitable to be used together.
INSIDE DRAINA 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.
INSULATIONMaterial which slows down or retards the flow or transfer of heat.
INSULATION FASTENERSAny of several specialized mechanical fasteners designed to hold insulation down
to a steel or a nailable deck.
INSULATION VENTA vent placed into the insulation which extends above the BURM.
INTERPLYBetween two layers of roofing felts that have been laminated together.
IRMAInsulated (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.
JOISTA horizontally placed timber or beam set on edge to give support to a floor or
KETTLEEquipment used for heating bitumen to a flowing consistency.
KICK HOLEA defect frequently found in perimeter flashings arising from being stepped on or
kicked. A small fracture of the base flashing in the area of the cant.
KRAFTA heavy water resistant paper.
LADDER, FIXEDA ladder which is permanently attached to a building.
LAPTo extend one material partially over another; the distance so extended.
LEADA malleable metal once extensively used for flashings.
LEAN-TO-ROOFthe sloping roof of a building addition having its rafters or supports pitched against
and supported by the adjoining wall of a building.
LIQUID-APPLIED MEMBRANEGenerally applied to cast-in-place concrete surfaces in one or more coats to
provide fully-adhered waterproof membranes which conform to all contours.
A roof which rises by inclined planes from all four sides of a building. The sloping
roofs on all four sides have two pitches, the lower pitch usually very steep and the
upper pitch less steep.
A heavy trowel applied bitumen used for flashings or patch work which remains
elastic and pliable.
The temperature at which the solid asphalt becomes a liquid.
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
The weight superimposed by snow or water or other tangibles which lack
permanency, not including the wind load, on a roof.