Glossary Of Terms


Aggregate– Crushed stone, crushed slag or water worn gravel used for surfacing a built-up roof.

Alligatoring– 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.  Alligatoring is not always indicative of roof failure or leakage.

Algae Discoloration– A type of roof discoloration caused by algae.  Commonly called fungus growth.  Many manufactures produce algae resistant shingles.  Look for “AR”.

Aluminum paint– An oil based coating mixed with aluminum particles, used for protecting asphalt roofs from UV rays & preserving a roofs life.

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

Apron Flashing
Metal flashing used at chimney fronts.

Asphalt Roofing Manufacturers Association. Organization of roofing manufacturers.

Asphalt– A black bitumen material used in roofing in hot or cold form, also called tar.

Asphalt Felt– An asphalt-saturated felt or an asphalt coated felt, primarily used as the base layer on sloped roofs.  A form of under lament and can come in #15 & #30.  #30 being the thicker of the two.

Asphalt Plastic Cement– An asphalt-based cement used to bond roofing materials.  Also known as flashing cement or mastic.

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 separate during delivery and storage.

Base Flashing– That portion of flashing attached to or resting on the deck to direct the flow of water onto the roof covering.

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

When shingles are subjected to high winds, and are forced off a roof deck.

When a wrinkle or ripple affects shingles or their underlayments

Built-up Roof– A flat or low pitched roof consisting multiple layers of asphalt and ply sheets.

Bundle(s)– A package of shingles.  There a generally 3 bundles to a square but can be 4 or 5 depending on weight.  Ex. GAF/ELK 50 year is 5 Bundles per square.


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

Caulk– To fill a joint with mastic or asphalt cement to prevent leaks.

Chalk Line– A line made on the roof by snapping a taut string or cord dusted with chalk.  Used for alignment purposes.

Class “A”– The highest fire-resistant rating issued by Underwriters Laboratories (UL) for roofing.  Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.

Class “B”– Rated to withstand moderate exposure to fire.

Class “C”– Rated to withstand light exposure to fire.

Class 4– The highest impact resistant shingle.

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

GAFMC’s respected brand name for ventilation products

Coating– A layer of viscous asphalt applied to the base material into which granules are embedded.

Counter Flashing – SEE CAP FLASHING

Cricket– A peaked saddle construction at the back of a chimney to prevent accumulation of snow and ice and to deflect water around the chimney.

Collar– Pre-formed flange placed over a vent pipe opening, also called a vent sleeve.

When shingles are improperly installed over an existing roof or are over-exposed, they may form a curl or cup. May also be due to a manufacturing defect.


Deck– The surface, installed over the supporting framing members, to which the roof is applied.

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

Downspout– A pipe for draining water from the roof gutters.

Drip Edge– A non-corrosive, non-staining material used along the eaves and rakes, flush with the fascia, to allow water run-off to drip clear of underlying construction.

Drying-In– The application of roofing felt to the rook deck.

Eaves–  The horizontal, lower edge of a sloped roof.


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.

Elastomeric – A rubber like synthetic polymer that will stretch when pulled and will return quickly to its original shape when released, primarily used for waterproofing walls and vertical surfaces.


Fascia– The wood trim covering the rafters and rafter ends, just beneath the drip edge.  Located at the end of the eaves and rakes.

Nails or staples used to secure roofing to the deck.

Felt– Fibrous material saturated with asphalt and used as an underlayment or sheathing paper.

Fiberglass Mat– An asphalt roofing base material manufactured from glass fibers.

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

Flashing– Pieces of metal or roll roofing used to prevent seepage of water into a building around any intersection or projection in a roof such as vent pipes, chimneys, adjoining walls, dormers and valleys.

Flashing CementSee Asphalt plastic cement.


Gable– The upper portion of a sidewall that corners to a triangular point at the ridge of a sloping roof.

Gable Roof– The upper portion of a sidewall that comes to a triangular point at the ridge of a sloping roof.

Galvanize– To plate with zinc, originally by shock galvanic action, providing protection from rust.

Granules– Ceramic, color-coated crushed rock that is applied to the exposed surface of asphalt roofing products.

Gutter – The trough that channels water from the eaves to the downspouts.


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– The inclined external angle formed by the intersection of two sloping roof planes.  Runs from the ridge to the eaves.

Hip Roof – A type of roof containing sloping planes of the same pitch on each of four sides.  Contains no gables.


Ice Dam
When a snow load melts on a roof and re-freezes at the eave areas. Ice dams force water to “back-up” under shingles 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 – Strip shingles containing more than one layer of tabs to create extra thickness.  Also called three-dimensional shingles.

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

Lead Pipe Jacks – A lead flashing installed over the PVC pipes that extend out through roof.

Low Slopes– Roof pitches less than a 4/12 pitch are considered low sloped roofs.  Special installation practices must be used on roofs sloped 2/12-4/12.


Mansard Roof– A type of roof containing two sloping planes of different pitch on each of four sides.  The lower plane has I much steeper pitch than the upper, often approaching vertical.  Contains no gables.

Mastic– See asphalt plastic cement.

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

Membrane– A flexible or semi-flexible roof covering or waterproofing layer, whose primary function is the exclusion of water.

Modified Bitumen – Rolled roofing membrane with polymer modified asphalt and either polyester or fiberglass reinforcement.

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.

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

Installing a second layer of shingles aligning courses with the original roof to avoid

Ninety-Pound (#90) – A prepared organic felt roll roofing with a granule surfaced exposure that has a mass of approx. 90 LBS per Square/100 Square feet.

NRCA– The National Roofing Contractors Association.


OpenValley– Method of valley construction is which shingles on both sides of the valley are trimmed along a chalk line snapped on each side of the valley.  Shingles do not extend across the valley.  Valley flashing is exposed.

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.

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

Overhang– That portion of the roof structure that extends beyond the exterior walls of a building.



Parapet Wall – The part of any wall entirely above the roof.

Pitch– The degree of roof incline expressed as the ration of the rise, in feet to the span, in feet.

Ply– The number of layers of roofing.  Generally applied to flat roofs, i.e. one-ply, two ply.

Power Vents– Electrically powered fans used to move air from attics and structures.  Installed through the decking.


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


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

Rafter– The supporting framing member immediately beneath the deck sloping from the ridge to the wall plate.

Rake– The inclined edge of a slope roof over a wall.

Rake Edge
The vertical edge of gable style roof planes.

Ridge– The uppermost, horizontal external angle formed by the intersection of two sloping roof planes.

Ridge Shingles – Shingles used to cover the ridge.  Also called ridge cap.

Rigid Vent
Hard plastic ridge vent material.

Rise– The vertical distance from the eaves line to the ridge.

Roll Roofing – Asphalt roofing products manufactured in roll form.  Used on low to no sloped roofs.

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.


The exposed section of double thickness on Timberline® Series shingles – also called dragon teeth. Shaped to imitate wood shake look on the roof.

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

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

Sheathing– Exterior grade plywood or tongue-and grove boards used as a roof deck.

Shed Roof – A roof containing only one sloping plane. Have no hips, ridges, valleys or gables.

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.

Slope– The degree of roof incline expressed as the ration of the rise, in inches, in the run in feet.

Smooth-Surface Roofing – Roll roofing that is covered with ground talc or mica instead of granules.

Soffit– The finished underside of eaves.

Square– A unit of roof measure covering 100 square feet. A 10’ x 10’ section.

Starter Strip – Asphalt roofing applied at the eaves that provides protection by filling in the spaces under the cutouts and joints of the first course of shingles.

Steep Slope Roofing
Generally all slopes higher than 4/12 are considered steep slopes.

Metal flashing pieces installed at sidewalls and chimneys for weatherproofing.

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


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

Removal of existing roofing materials down to the roof deck.

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

Three Tab Shingles – Flat asphalt roofing shingles.  20,25 & 30 year warranty.  The cheapest form of shingles.

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

GAFMC enhanced Hip and Ridge Shingles.

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


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

Underlayment – A layer of material under the roofing and on top of the decking.  Mainly felt, #15 or #30.


Valley– The internal angle formed by the intersecting of two sloping roof planes.

Term used to describe moisture laden air.

Vent– Any outlet for air that protrudes through the roof deck such as a pipe of stack.  Any device installed on the roof, gable or soffit for the purpose of ventilating the underside of the roof deck/attic.


Warm Wall
The finished wall inside of a structure, used in roofing to determine how far up the deck to install waterproof underlayments at eaves.

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.

GAFMC’s granule surfaced waterproof underlayment.

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