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Algae – Rooftop fungus that can leave dark stains on roofing shingles.
Apron Flashing – Metal flashing used at chimney fronts.
Asphalt – A bituminous waterproofing agent used in various types of roofing materials.


Blistering – Bubbles and pimples in roofing materials. Usually moisture related. In shingles, blisters are usually moisture trapped under the shingles or in the shingles.
Blow–offs – When shingles are subjected to high winds, and are forced off a roofing deck.
Buckling – When a wrinkle or ripple affects shingles or their underpayments.


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.
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. This method is also known as a western valley.
Corrosion – When rust, rot or age negatively affect roofing materials.
Counter Flashing – The metal or siding material that is installed over roof-top base flashing systems.
Crickets – A peaked water diverter installed behind chimneys or other 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 out over eaves and gutters, and prevents water from backing up under shingles.


Eaves – A roof edge from the fascia to the structure’s outside wall. In general terms, the first three feet across the roof is termed the eave.
Exposure – The area of any roofing material that is exposed to the elements.


Fasteners – Nails or staples used to secure roofing materials to the deck.
Felt – Organic or paper-based rolled material saturated with asphalt to serve as roofing underlayment.
Fiberglass Mat – Fibers condensed into strong, resilient mats for use in roofing materials.
Flange – Metal pan extending up or down a roof slope around any projections through the roof deck.
Flashing – Materials used to waterproof a roof around any projections through the roof deck.
Flat Roof – Flat roofs by nature have a pitch of less than 1.5 degrees, and are often used for commercial roofs or roofs in more arid climates.


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 a top surface on shingles.


Hand-sealing – The method used 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 a hip roof.
Hip Roof – A roof with four planes coming together at a peak and four separate hip legs.


Ice and Water Shield – A rubberized membrane with adherent on backing used as an underlayment on roof decks. This product will provide a leak proof seal for problem areas such as valleys, chimneys, skylights and eaves.
Ice Dam – When a snow load melts on a roof and re-freezes at the eave areas. Ice dams cause water to “back-up” a roof and cause a leak.


“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 underlayments overlap one another during application.
Low-Slopes – Roof pitches less than 4/12 are considered low sloped roofs. Special installation practices must be used on roof slopes 2/12 – 4/12.


Mansard – A roof design with a nearly vertical roof plane that ties into a roof plane of a lesser 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 to bond 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 cupping.


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.
OSD – 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 extract warm air and moisture 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 Winds – The most common direction of wind for a particular region.


Quarter Sized – Term for the size of hand sealant dabs, size of a 25 cent piece.


Racking – Method for 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 Llouvers – Rooftop rectangular shaped roof vents. Also called box vents, mushroom vents, airhawks and soldier vents.
Roof Plane – A roofing area defined by having four separate edges. One side of a gable, hip or mansard 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. Baron Roofing’s only brand of underlayment used in installation of all sloped roofing systems because of the superior performance properties of this particular product.
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 eaves or at roof edge.Starter strip – The first course of roofing installed. Usually trimmed from main roofing 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 shingles 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 buckling.
Transitions – When a roof plane ties into another roof plane with 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 impression.
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 bases roofing underlayments. Designed to seal to wood decks and waterproofing critical leak areas.
Woven Valley – The method of installing valleys by laying one shingle over the other up the valley centre.