Glossary of Roofing Terms

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What are the common roofing system terms?

Asphalt – Organic bituminous compound used in the manufacturing of composition shingles.

Asphalt Roofing Cement – The safest cement used on asphalt singles. It’s used to bond roofing materials, also known as flashing cement or mastic.

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

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

Blend – Mixtures of differently colored granules on the surface of shingles.

Blind Nailing – Nails driven in such a way that the heads are concealed by following layers of roofing materials.

Blisters – Bubbles that appear on the surface of asphalt roofing that are caused by many different reasons. Manufacturing defects, under ventilated roof system, non compatible adhesive use and improper fastening.

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 instead of using this method.

Built–Up Roofing – A flat or low sloped roof made up of layers of asphalt and ply sheets.

Butt – The portion of the shingle exposed to the weather (visible), sometimes called the “tab” of the shingle.

Cant Strip – A 45 degree beveled wood, fiberboard, or metal strips at the junctions of a roof and a vertical surface used to break a right angle. Primarily used in low slope applications.

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 (also known as counter flashing) is generally not changed in a reroofing job unless visibly damaged or corroded.

Caulk – Substance used to fill a joint or void.

Cement – A substance, when cured, binds to surfaces together. Heavy application is required in most coastal communities to improve high wind resistance of roofing systems.

Class A – 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 – Roofing materials cover the entire valley. Unless otherwise requested, Ridge Valley Exteriors. usually installs closed valleys on their homes following the preferred method of Owens Corning.

Coating – Layer of viscous asphalt applied to shingles in which granules are then embedded.

Collars – Are a pre–formed flange placed over a vent pipe. (also known as vent sleeve) There are two types, lead jacks and rubber boots.

Counter Flashing – see Cap Flashing for definition.

Course – Horizontal unit of roofing running the length of the roof. If run incorrectly, the roof will have a wavy or tilted look to it.

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

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

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

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Deck – Material installed over the support structure of the roof on which shingles are installed. The primary materials are Oriented Strand Board (OSB) and CDX Plywood. Most follow recommended gapping during installation.

Double Coverage – 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.

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 – Portion of the shingle that is exposed to the elements. usually measured from the butt of one shingle to the butt of the next overlapping shingles.

Master Elite® Certification – GAF’s factory certification program that provides ongoing training to roofing contractors and assurance to you that the roof will be completed well and professionally. Only 2% of all roofing contractors have qualified as Master Elite® Choosing a GAF Master Elite® contractor is your assurance that you’ll be dealing with a quality, and dependable professional contractor.

Lap – The overlap of surface of one roofing material to another.

Laminated Shingles – Shingles containing more than one layer of tabs creating extra thickness. (also known as dimensional or architectural shingles).

Lock Shingles – Shingles with a mechanical locking feature. These are not very commonly used.

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

Mansard Roof – 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 additional 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.

Owens Corning Platinum Preferred Contractor – Owens Corning Roofing Platinum Preferred Contractors are the top tier of our exclusive network and meet strict standards for professionalism, reliability and unparalleled craftsmanship. Only they can offer our best roofing system warranty.

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 additional wind resistance.

heathing – Exterior grade boards used as a roof deck.

Side Lap – Horizontal lap

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

Slope – The degree of incline of a roof plane.

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Soffit – The finished underside of an eave usually constructed of plywood and painted.

Soffit Vent – An under eve opening needed for intake of outside air. These are not part of a typical roofing job, but are key to ensure attic ventilation to make sure you get the most life from your roofing system and a properly breathing home or building.

Soil Stack – Vent pipe that penetrates the roof.

Span – Horizontal measurement from eave to eave.

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

Square – A unit of roof measurement covering 100 square feet.

Square Butt Shingles – Generally a three tab 20 year shingle – not laminated.

Starter Course – This is the first course of shingles installed on your roof under the first exposed row. Often these shingles are 20 year three tab shingles so it creates a uniform look. This is used even when heavier laminated shingles are being 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 comes in 4x4x8 inch pieces.

Tab – Portion of strip shingles defined by cut outs or slots so when installed, the 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. Ridge Valley Exteriors only uses synthetic underlayment because of it’s far superior quality and durability.

Valley – Intersection of two roof slopes.

Vent – An outlet for air

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

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