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Roofing Terms

Roofing Terms: A-I


(1) Crushed stone, crushed slag or water-worn gravel used for surfacing a built-up roof. (2) Any granular mineral material.


The cracking of the surfacing bitumen on a built-up roof, producing a pattern of cracks similar to an alligator’s hide; the cracks may or may not extend through the surfacing bitumen.

Ambient Temperature

Temperature of air – – air temperature.

Application Rate

The quantity (mass, volume or thickness) of material applied per unit area.

Area Divider

A raised, double wood member attached to a properly flashed wood base plate that is anchored to the roof deck. It is used to relieve thermal stresses in a roof system where no expansion joints have been provided.


A group of natural, fibrous, impure silicate materials.


An organic bituminous compound used in the manufacturing of composition shingles.

Asphalt Roofing Cement

Used to bond roofing materials, also known as flashing cement or mastic.

Asphalt, Air Blown

An asphalt produced by blowing steam through molten asphalt to modify its properties, normally used for highway bitumen.


American Society for testing of Materials. A voluntary organization concerned with the development of standards, testing procedures, and specifications. Many city building codes use ASTM standards.

Atactic Polypropylene

A group of high molecular weight polymers formed by the polymerization of propylene.

Back Nailing

The practice of blind nailing (in addition to hot mopping) all the plies of a substrate to prevent slippage.


An anchoring material, such as aggregate, precast pavers, which employ the force of gravity to hold (or assist in holding) membranes in place.

Base Flashing

The portion of the flashing which is attached to, or rest on the roof deck.

Base Ply

The base ply is the first ply when it is a separate ply and not part of a shingled system.

Base Sheet

A saturated or coated felt placed as the first ply in some multi-ply built up roof membranes.


A clay formed from decomposed volcanic ash, with a high content of the mineral montmorillonite; has the capacity of absorbing a considerable amount of water, and swells accordingly.


The generic term for an amorphous, semi-solid mixture of complex hydrocarbons derived from any organic source. Asphalt and coal tar are the two used in the roofing industry.


Mixtures of various colored granules on the surface of shingles.

Blind Nailing

Nails driven in such a way that the heads are concealed by succeeding layers of roofing materials.


Bubbles that may appear on the surface of asphalt roofing.


A method of reroofing where the new shingles follow the contour of the old roofing. Also called “butting up”. It is almost always desirable to tear off old roofing.

Built-Up Roofing

A flat or low sloped roof made up of layers of asphalt and ply sheets. (AKA BUR)


The portion of the shingle exposed to the weather, sometimes called the “tab” of the shingle.

Cant Strip

A 45 degree beveled wood, fiberboard, or metal strips at the junction of the roof and a vertical surface used to break a right angle. Primarily used in low sloped roofing.

Cap Flashing

Flashing on a vertical surface to prevent the flow of water from getting behind the base flashing. The cap flashing overlaps the base flashing. This flashing (AKA counter flashing) is generally not changed in a reroofing job.


A substance used to fill a joint or void.


A substance, when cured, binds to surfaces together.

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The highest fire resistance rating for roofing as per ASTM E-108. Shingle with this rating should withstand severe exposure to fire from sources originating outside the building. Other classed are B and C.

Closed Valley

When roofing materials cover the entire valley. Unless otherwise requested, Bert Roofing Inc. primarily installs closed valleys.


Pre-formed flange placed over a vent pipe. (AKA vent sleeve) There are two types, lead jacks and rubber boots.

Counter Flashing

See Cap Flashing.


A horizontal unit of roofing running the length of the roof.

Dead Level

A structure rising above the main roof. It is usually ornamental, but may be used for ventilation.


a roof or section of roof without any pitch.


The material installed over the framing of a structure on which shingles are installed. The primary materials are Oriented Strand Board (OSB) and cdx Plywood.

Double Coverage

A method of applying roof shingles so that two complete layers of material are provided.


A window unit projecting through the sloping plane of the roof.

Drip Edge

Usually metal strip used on eves and rakes to allow for water run off without damaging underlying materials.

Drip Course

The first course of shingles that slightly overhangs the edge.


The horizontal edge of a roof that projects over the outside wall.


The portion of the shingle that is exposed to the weather. usually measured from the butt of one shingle to the butt of the next overlapping shingles.

Roofing Terms: J-Q


The overlap of surface of one roofing material to another.

Laminated Shingles

Shingles containing more than one layer of tabs creating extra thickness. (AKA dimensional or architectural)

Lock Shingles

Shingles with a mechanical locking feature. These are not common.

Low Slope Application

A method of applying shingles on slopes between 2 and four inches per foot.

Mansard Roof

A vertical portion of roofing.


See Asphalt Roof Cement.

Modified Bitumen

Roller roofing membrane with a polymer modfied asphalt. The roll will generally have a fiberglass or polyester mat for reinforcement.


See Bridging.

Normal Slope Application

Method of installing shingles between 4 and 21 inches per foot.

Open Valley

Valley in which metal is used and roofing material does not cover entire valley area as in a Closed Valley.

Roofing Terms: R-Z


Asphalt used to impregnate felt for waterproofing and strength.

Seal Down

A factory applied asphalt strip used to bond a shingle to the one above. This is used to provide wind resistance.


Exterior grade boards used as a roof deck.

Side Lap

A horizontal lap.

Skirt Flashing

A large often single piece of flashing commonly found at the bottom of a dormer or addition.


The degree of incline of a roof plane.


The finished underside of an eave.

Soffit Vent

An under eve opening needed for intake of outside air. These are not part of a typical roofing job, but are needed for good attic ventilation.

Soil Stack

A vent pipe that penetrates the roof.


The horizontal measurement from eave to eave.


A tower of roof tapering up to a point.


A unit of roof measurement covering 100 square feet.

Square Butt Shingles

Generally three tab 20 year shingles – not laminated.

Starter Course

The first course of shingles installed on your roof. It will be under the first exposed row. Often these shingles are 20 year three tab shingles. So as to not create an awkward hump, these are used even when heavier laminated shingles are installed.

Step Flashing

The flashing along a roof slope against a wall or chimney using succeeding courses of flashing material placed in conjunction with layers or courses of roofing materials. Step Flashing is generally in 4 by 4 by 8 inch pieces.


Portion of strip shingles defined by cut outs or slots so when installed, material appears to be individually applied.


An asphalt saturated felt applied over the roof deck and under the roofing material. Homeowners hould know there is a wide range of both quality and price in underlayments.


The intersection of two roof slopes.


An outlet for air.


Changes in color, texture or efficiency brought about by exposure to outside elements.


Changes in color, texture or efficiency brought about by exposure to outside elements.

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