Glossary of Roofing Terms


Asphalt is an organic bituminous compound used in the manufacturing of composition shingles.

Asphalt Roofing Cement
Asphalt Roofing Cement  is used to bond roofing materials. It is also known as flashing cement or mastic.

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


Base Flashing
Base Flashing is the portion of the flashing that is attached to, or rests on the roof deck.

Blend is the mixture of various colored granules on the surface of shingles.

Blind Nailing
Blind nailing refers to nails driven in such a way that the heads are concealed by succeeding layers of roofing materials.

Blisters are bubbles that may appear on the surface of asphalt roofing.

Bridging is a method of reroofing where the new shingles follow the contour of the old roofing. It is also called “butting up”.

Built-up Roofing
Built-up Roofing is a flat or low sloped roof made up of layers of asphalt and ply sheets.

A butt is the portion of a shingle exposed to the weather. It is sometimes called the “tab” of the shingle.


Cant Strip
A cant strip is a 45 degree beveled wood, fiberboard, or metal strip located at the junction of the roof and a vertical surface used to break a right angle. It is primarily used in low sloped roofing.

Cap Flashing
Cap flashing is flashing installed 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 replaced in a reroofing job.

Caulk is a substance used to fill a joint or void.

Cement is a substance, when cured, binds two surfaces together.

Class “A”
Refers to the highest fire resistance rating for roofing as per ASTM. Shingles with this rating are designed withstand severe exposure to fire from sources originating outside the building.  Other classes are B and C.

Closed Valley
A closed valley exists when roofing materials cover an entire valley.

A coating is a layer of viscous asphalt applied to shingles in which granules are embedded.

Collars are pre-formed flanges placed over a vent pipe. (AKA as a vent sleeve).

Counter Flashing
See Cap Flashing.

A course is a horizontal section of roofing running the length of a roof.


Dead Level
Dead level refers to a section of roof without any pitch.

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

Double Coverage
Double coverage is a method of applying roof shingles so that two complete layers of material are provided.

A dormer is a window unit projecting through the sloping plane of a roof.

Drip Edge
A drip edge is the metal strip used on eves and rakes to allow for water run off without damaging the underlying materials.

Drip Course
A drip course is the first course of shingles that slightly overhangs the edge.


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

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


Lap refer to the overlap of one roofing material to another.

Laminated Shingles
Laminated shingles are shingles containing more than one layer of tabs creating extra thickness.


Mastic is a type of asphalt roof cement.

Modified Bitumen
Modified Bitumen is a roller roofing membrane with a polymer modified asphalt. The rolls generally have a fiberglass or polyester mat for reinforcement.


Saturant is asphalt used to impregnate felt for waterproofing and strength.

Seal Down
Seal down is a factory applied asphalt strip used to bond shingles to the ones above. It is used to provide wind resistance.

Sheathing consists of exterior grade boards that are used as a roof decking.

Skirt Flashing
Skirt flashing is a large often single piece of flashing usually found at the bottom of a dormer.

Slope is the degree of incline of a roof plane.

A soffit is the finished underside of an eave.

Soffit Vent
A soffit vent is an under eve opening for the intake of outside air.  These are not part of a typical roofing job, but are needed for good attic ventilation and cooling.

Soil Stack
Soil stack is a vent pipe that penetrates the roof.

The span is the horizontal measurement from eave to eave.

A square is a unit of roof measurement equal to 100 square feet.

Square Butt Shingles
Square Butt Shingles are generally three tab 20 year shingles.

Starter Course
The starter course is the first course of shingles on a roof.


Tab refers to the portion of strip shingles defined by cut outs or slots.


Underlayment refers to asphalt saturated felt applied over the roof deck and under the roofing material. There is a wide range of quality in underlayment.


A valley is the intersection of two roof slopes.

A vent is an outlet for air.


Weathering refers to changes in color, texture or efficiency brought about by exposure to outside elements such as the sun and extreme weather.