Roof Glossary


Algae: Rooftop fungus that can leave dark stains on roofing.

Angled fasteners: Roofing nails and staples driven into decks at angles not parallel to the deck.

APA: American Plywood Association. Tests and sets standards for all varieties of plywood used in the U.S.

Apron flashing: Metal flashing used at chimney fronts.

ARMA: Asphalt Roofing Manufacturer’s Association. Organization of roofing manufacturers.

Asphalt: A bituminous waterproofing agent used in various types of roofing materials.

Asphalt concrete primer: Asphalt based primer used to prepare concrete and metal for asphalt sealant.

Asphalt plastic cement: Asphalt based sealant material, meeting ASTM D4586 Type I or II. Used to seal and support roofing materials. Also called mastic, blackjack, roof tar, and bull.

ASTM: The American Society for Testing and Materials. Organization that sets standards for a wide variety of materials, including roofing.



Back-surfacing: Granular material added to shingle’s back to assist in keeping them separate during delivery and storage.

Blistering: Bubbles or pimples in roofing materials. Usually moisture related. In shingles blisters are either moisture under the material or moisture trapped inside the material.

Blow-offs: When shingles are subjected to high winds, and are forced off a roof deck.

Buckling: When a wrinkle or ripple affects shingles or their underlayments



Closed-cut valley: A shingle valley installation method where one roof plane’s shingles completely cover the others. The top layer is cut to match the valley lines.

Cobra® : GAFMC’s respected brand name for ventilation products.

Corrosion: When rust, rot or age negatively affect roofing metals.

Counter-flashing: The metal or siding material that is installed over roof-top base flashing systems.

Country Mansion® & Country Estates™: GAFMC’s limited lifetime warranty shingle.

Crickets: A peaked water diverter installed behind chimneys and other large roof projections. Effectively diverts water around projections.

Cupping: When shingles are improperly installed over an existing roof or are over-exposed, they form a curl or cup.



Deck: The substrate over which roofing is applied. Usually plywood, wood boards, or planks.

Dormer: A raised roof extending out of a larger roof plane.

Drip-edge: An installed lip that keeps shingles up off of the deck at edges, and extends shingles out over eaves and

gutters, and prevents water from backing up under shingles.

Dubl-Coverage® Mineral Guard: Roll roofing material with 19″ selvage edge for double coverage over roof deck.



Eaves: The roof edge from the fascia to the structure’s outside wall. In general terms, the first three feet across a roof is termed the eave.

End-laps: When installing rolled products in roofing, the area where a roll ends on a roof, and is overlapped by the next section of rolled material. (underlayments, rolled roofing)

Exposure: The area on any roofing material that is left exposed to the elements.



Fasteners: Nails or staples used in securing roofing to the deck. Felt-Organic or paper-based rolled material saturated with asphalt to serve as roofing underlayment.

FHA: The Federal Housing Authority. Sets construction standards throughout the U.S.

Fiberglass mat: fibers condensed into strong, resilient mats for use in roofing materials.

Flange: Metal pan extending up or down a roof slope around flashing pieces. Usually at chimneys and plumbing vents

Flashing: Materials used to waterproof a roof around any projections through the roof deck.

Flashing cement: Sealant designed for use around flashing areas, typically thicker than plastic cement.



Gable roof: Traditional roof style; two peaked roof planes meeting at a ridge line of equal size.

GAFCant®: GAFMC cant strips for deflecting water away from flashing areas. Typically used on low slope roofs.

Golden Pledge®: GAFMC’s strongest limited warranty for shingles. America’s strongest steep slope warranty.

Grand Sequoia®: GAFMC shingle with wood shake appearance.

Grand Slate™: GAFMC shingle with slate appearance.

Granules: Crushed rock that is coated with a ceramic coating and fired, used as top surface on shingles.



Hand-sealing: The method to assure sealing of shingles on very steep slopes, in high wind areas, and when installing in cold weather.

High nailing: When shingles are nailed or fastened above the manufacturer’s specified nail location.

Hip legs: The down-slope ridges on hip roofs.

Hip roof: A roof with four roof planes coming together at a peak and four separate hip legs.



Ice Dam: When a snow load melts on a roof and re-freezes at the eave areas. Ice dams force water to “back-up” a roof and cause leakage.



“L” flashing: Continuous metal flashing consisting of several feet of metal. Used at horizontal walls, bent to resemble an “L”.

Laminated shingles: Shingles made from two separate pieces that are laminated together. GAFMC Timberline® Series, Country Mansion® and Grand Sequoia® Shingles. Also called dimensional shingles and architectural shingles.

Laps: The area where roll roofing or rolled underlayments overlap one another during application (see also side laps and end laps).

Low: slopes-Roof pitches less than 4/12 are considered low sloped roofs. Special installation practices must be used on roofs sloped 2/12-4/12.



Mansard: A roof design with a nearly vertical roof plane that ties into a roof plane of less slope at its peak.

Mats: The general term for the base material of shingles and certain rolled products.

Modified bitumen: Rolled roofing membrane with polymer modified asphalt and either polyester or fiberglass reinforcement.

Mortar: Mixture of sand, mortar, limestone and water used in bonding a chimney’s bricks together.



Nail-guide-line: Painted line on laminated shingles, to aid in the proper placement of fasteners.

Nail-pop: When a nail is not fully driven, it sits up off the roof deck.

Nesting: Installing a second layer of shingles aligning courses with the original roof to avoid shingle cupping.

NRCA: The National Roofing Contractors Association. Respected national organization of roofing contractors.



Open valley: Valley installation using metal down the valley center.

Organic mat: Material made from recycled wood pulp and paper.

Organic Shingles: Shingles made from organic (paper) mats.

OSB: Oriented Strand Board. A decking made from wood chips and lamination glues.

Over-driven: The term used for fasteners driven through roofing material with too much force, breaking the material.

Over-exposed: Installing shingle courses higher than their intended exposure.



Pitch: ratio of the rise of the roof to the span of the roof.

Power vents: Electrically powered fans used to move air from attics and structures.

Plastic cement: Asphalt based sealant. Also called bull, mastic, tar, asphalt cement.

Plumbing vents: Term used to describe plumbing pipes that project through a roof plane. Also called vent stacks.

Prevailing wind: The most common direction of wind for a particular region.



Quarter sized: Term for the size of hand sealant dabs, size of a U.S. 25¢ piece.



Racking: Method of installing shingles in a straight up the roof manner.

Rake edge: The vertical edge of gable style roof planes.

Release film: The plastic sheet installed on the back of Weather Watch® and StormGuard® underlayments. Used for packaging and handling. Remove before installation.

Rigid vent: Hard plastic ridge vent material.

Roof louvers: Rooftop rectangular shaped roof vents. Also called box vents, mushroom vents, airhawks, soldier vents.

Roof plane: A roofing area defined by having four separate edges. One side of a gable, hip or mansard roof.



Sawteeth: The exposed section of double thickness on Timberline® Series shingles. Shaped to imitate wood shake look on the roof.

Self-sealant: Sealant installed on shingles. After installation, heat and sun will activate sealant to seal the shingles to each other.

Selvage: The non exposed area on rolled roofing. Area without granules. Designed for nail placement and sealant.

Shed roof: Roof design of a single roof plane. Area does not tie into any other roofs.

Shingle-Mate®: GAFMC’s shingle underlayment. Breather type with fiberglass backing to reduce wrinkles and buckles.

Side-laps: The area on rolled material where one roll overlaps the rolled material beneath it. Also called selvage edge on rolled roofing.

Side-walls: Where a vertical roof plane meets a vertical wall. The sides of dormers etc.

Soffit ventilation: Intake ventilation installed under the eaves, or at the roof edge.

Smart Choice® Limited Warranty: GAFMC’s standard shingle limited warranty.

Smart Choice® System Plus Limited Warranty: GAFMC’s next grade of enhanced warranty. Extended coverage for owners.

Starter strip: The first course of roofing installed. Usually trimmed from main roof material.

Steep slope roofing: Generally all slopes higher than 4/12 are considered steep slopes.

Step-flashing: Metal flashing pieces installed at side-walls and chimneys for weather-proofing.

StormGuard®: GAFMC waterproof underlayment. Film surfaced rolled underlayment, 1.5 squares coverage per roll.



Tab: The bottom portion of traditional shingle separated by the shingle cut-outs.

Tear-off: Removal of existing roofing materials down to the roof deck.

Telegraphing: When shingles reflect the uneven surface beneath them. Shingles installed over buckled shingles may show some buckles.

Timberline® Series: GAFMC’s trademark name for laminated wood shake style shingles.


TIMBERTEX®: GAFMC enhanced Hip and Ridge Shingles.

Transitions: When a roof plane ties into another roof plane that has a different pitch or slope.



Under-driven: Term used to describe a fastener not fully driven flush to the shingles surface.

Underlayments: Asphalt based rolled materials designed to be installed under main roofing material, to serve as added protection.



Valleys: Area where two adjoining sloped roof planes intersect on a roof creating a “V” shaped depression.

Vapor: Term used to describe moisture laden air.

Ventilation: The term used in roofing for the passage of air from an enclosed space.



Warm wall: The finished wall inside of a structure, used in roofing to determine how to install waterproof underlayments at eaves.

Warranty: The written promise to the owner of roofing materials for material related problems.

Waterproof underlayments: Modified bitumen based roofing underlayments. Designed to seal to wood decks and waterproof critical leak areas.

Weather Stopper® Integrated Roofing System™: GAFMC’s complete roofing system and components.

Weather Watch®: GAFMC’s granule surfaced waterproof underlayment.

Woven Valleys: The method of installing valleys by laying one shingle over the other up the valley center.