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 plywoods 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 adhere roofing materials. Also called mastic, blackjack, roof tar, 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 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 other’s. The top layer is cut to match the valley lines.

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.

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.

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.

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.  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.

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 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.

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.

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.

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.

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.

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