The binding together of membrane and substrate.

A pattern of rough cracking, similar in appearance to alligator skin.  Occurs when another coating is applied before previous coat is dry or by exposing the surface to extreme heat.

Dark brown or black bitumen pitch that melts readily.  Appears naturally in asphalt beds, but is also created as a by-product of petroleum processing.

Flashing that covers the edges of a membrane.

The saturated and/or coated felt sheeting laid on the first ply in a built-up roof system.

Mixtures of naturally occurring synthetically rendered substances obtained from coal or petroleum.  Bitumen is incorporated into asphalt and coal tar used roofing, road and waterproofing.

An undesirable moisture or air bubble, often an indication of delamination.  Blisters may occur between roofing membranes or between the membrane and substrate.

A continuous roof covering consisting of sheets of saturated or coated felt, cemented together with asphalt.  The felt sheets are topped with a flood coat of asphalt, which may have a surfacing of applied gravel.

A three-sided piece of wood, one angle is square, used under the roofing on a flat roof when the horizontal surface abuts a vertical wall or parapit.  The sloped transition facilitates roofing and waterproofing.

A soft, putty-like material used to fill joints, seams and cracks.

The underlying sheet of asphalt-impregnated felt used in built-up roofing.

Protective top of any vertical construction, such as a wall or chimney.  It may be made of masonry, metal or wood and is usually sloping or beveled to shed water, so that it does not run down the vertical face of the wall.

A thin strip of metal frequently inserted into masonry construction and bent down over other flashings to prevent water from running down the masonry and behind the upturned edge of the base flashing.

A layer of any type of building material, such as siding or shingles, applied for purposes of waterproofing.

A fracture or break caused by thermal stress or substrate movement.

Slow, continuous permanent deformation of a material under sustained stress. In roofing, creep is caused by movement of the roof membrane under stress.

A structure superimposed on a roof to facilitate drainage.

A frame that protrudes above the surface of the roof, at the edge and/or penetrations to facilitate flashing.

A seal that is applied in order to isolate sections of the roof system to prevent water from running toward unfinished work areas and damaging exposed membranes.

The structural system to which a roof covering is applied.

Deterioration of a surface caused by heat,  light, moisture or other elements.

To prevent bitumen leakage, an envelope or felt fold is created by wrapping part of a base felt over the felt plies above it.

Rubber membrane that is fully adhered, ballasted or mechanically fastened in a roof system.

A gap or joint between adjacent parts of a building structure or concrete work which allows for sag and inconsequential relative movement of the parts, as caused by thermal variations or other conditions.

Unit of measure; 108 square feet or 10 square meters of roofing material.

A fabric composed of matted, compressed fibers, usually manufactured from the cellulose fibers found in wood, paper or rags, or from asbestos or glass fibers.

A semi-conical opening formed at the cut edge of a shingle.

A thin, impervious sheet of material placed in construction to prevent water penetration or to direct the flow of water.  Flashing is used especially at roof hips and valleys, roof penetrations, joints between a roof and a vertical wall, and in masonry walls to direct the flow of water and moisture. 

A metal strip of flange around the edge of a built-up roof.  The stop prevents loose gravel or other surfacing materials from washing or being blown off a roof.

A shallow channel of wood, metal or PVC positioned just below and following along the eaves of a building for the purpose of collecting and diverting water from a roof.

In construction, a type of joint in which two building elements are not butted up against each other, but are overlapped, with part of one covering part of the other.

A roof that has a change of slope on each of the four sides, the lower slope being steeper.

The impervious layer or layers of material used for water control in the construction of a flat roof.

Measurement of thickness.  One Mil equals .001 inch.

The addition of plastic or rubber binders to asphalt to improve its performance and weatherability.

The application of hot bitumen to a roof substrate, using either a mop or a machine.

A volcanic glass used as an insulation material or as a lightweight aggregate in concrete, mortar and plaster.

A method of sealing joints in which a flanged metal container is placed around roof penetrations and filled with a pourable sealer that hardens to shed water.

A layer.  In built-up roofing, a ply is a layer of felt.

A groove in a wall to receive flashing.

The elements of a roof assembly, excluding the roof deck.

A material used to seal joints where some movement is anticipated.

A crack, tear or separation in a built-up membrane resulting from movement or tensile stresses.

A quantity of shingles, shakes or other roofing or siding materials sufficient to cover 100 square feet when applied in a standard manner;  the basic sales units of shingles or shakes.

A strip of insulation used to: (1) make the transition from one layer of insulation to the next, (2) raise the roof around the perimeter and at curbs.

A 4" x 40" sample cut from the roof membrane in order to determine the weight of the interply bitumen poundage and to determine the condition of the roof membrane.