Roofing Glossary Terms

Asphalt – 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

ASTM – 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.

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

Blend– 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.

Blisters – Bubbles that may appear on the surface of asphalt roofing.

Bridging – 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)

Butt – 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.

Caulk – A substance used to fill a joint or void.

Cement – A substance, when cured, binds to surfaces together.

Class “A” Fire Resistance - The highest fire test classification for roofing as per ASTM E108 or UL790. Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.

Class “B” Fire Resistance - Fire test classification that indicates roofing material is able to withstand moderate exposure to fire originating from sources outside the building.

Class “C” Fire Resistance - Fire test classification that indicates roofing material is able to withstand light exposure to fire originating from sources outside the building.

Class 4 Impact Resistance - The highest impact resistance classification as per the UL 2218 Impact test indicating that shingles are more resistant to impacts resulting from hail storms.

Closed Cut Valley - A method of valley treatment in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed 2” from the valley centerline. The valley flashing is not exposed.

Coating – A layer of viscous asphalt applied to shingles in which granules are embedded.

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

Concealed Nail Method - Application of roll roofing in which all nails are driven into the underlying course of roofing and covered by a cemented, overlapping course. Nails are not exposed to the weather.

Condensation - The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.

Counter Flashing - That portion of the flashing attached to a vertical surface to prevent water from migrating behind the base flashing.

Course - A row of shingles or roll roofing running the length of the roof.

Coverage - The number of layers of material between the exposed surface of the roofing and the deck; i.e., single coverage, double coverage, etc.

Cricket – A small peaked saddle constructed on the top of the basic roof and behind the chimney. A cricket is generally not required.

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

Dead Level – A roof or section of roof without any pitch.

Deck – 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.

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

Downspout - A pipe for draining water from roof gutters. Also called a leader.

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.

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

Exposure – 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.

Lap – 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 – A shingles with a mechanical locking feature. These are not common.

Low Slope Application – Method of applying shingles on slopes between 2 and four inches per foot.

Mansard Roof – A vertical portion of roofing.

Mastic – See asphalt roof cement.

Modified Bitumen – Roller roofing membrane with a polymer modified asphalt. The roll will generally have a fiberglass or polyester mat for reinforcement.

Nesting – 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.

Saturant – 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.

Sheathing – 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.

Slope – The degree of incline of a roof plane.

Soffit – 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.

Span – The horizontal measurement from eave to eave.

Spire – A tower of roof tapering up to a point.

Square – 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 – 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.

Strip Shingles - Asphalt shingles made from a single layer that are approximately three times as long as they are wide.

Synthetic Underlayment - An underlayment product that is typically manufactured using polypropylene and is used as an alternative to felt underlayment.

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

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

Valley – The intersection of two roof slopes.

Vent – An outlet for air

Weathering – changes in color, texture or efficiency brought about by exposure to outside elements.

Woven Valley -  Method of valley construction in which shingles from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied. The valley flashing is not exposed.