Roofing glossary of terms

Ever feel like your roofers are speaking a language of their own? We’ve put together a huge list of roofing terms so that you’ll always be in the know when it comes to your roofing project.

Still have questions? Contact our office in Calgary or Edmonton today and get the answers you’re looking for! Our friendly, knowledgeable technicians are always glad to help. You can also visit us online at any time to receive a free quote!

Accelerated weathering

A test by which roofing materials are exposed to various elements like heat, water, condensation, or light in order to measure their resilience.

Air barrier

A construction element used to control the passage of air through a building.

Alligatoring

A pattern of cracks that develops on surface bitumen that looks very much like an alligator’s skin.

Apron flashing

Describes the flashing used where a sloped roof meets a vertical wall, another section of roof, or a chimney.

Architectural shingles

Shingles used to create a dimensional appearance for design purposes.

Asphalt

A bituminous substance that remains after processing crude oil or petroleum. Used in roofing for its waterproofing properties.

Asphalt roof cement

A mud-like mixture of bitumen, asphalt, fillers, and stabilizers.

Asphalt shingles

Shingles made by coating a base material like felt or fibreglass with asphalt on 1 side and granulated minerals on the other side.

Barrel roof

An architectural feature that gives a rounded profile to a portion of the roof.

Base flashing

Pieces of roof material used to seal off a roof at its vertical intersections, like when the roof meets the wall.

Batten

A wooden or metal strip that is used to hold the base flashing or the roof’s membrane down.

Bitumen

A dark-coloured cement-like substance. Generally used to refer to asphalt or coal tar.

Blackberry

A little blister in the flood coating applied to the roof membrane.

Blocking

The use of various blocks of wood to stiffen the deck, serve as stops or supports, or simply a place to nail when attaching roof membrane or flashing.

Buckle/buckling

Wrinkling or rippling that distorts the shape of the shingles and/or underlay. Usually caused by some movement of the roof deck. Most common in board decks.

Built-up roof (BUR)

Multi-layered roof membrane and bitumen with a granule-surfaced cap sheet.

Cant

A piece of foam that is cut on a bevel, both to add strength to right-angled joints and to seal up any gaps. Also helps with water run-off.

Cavity wall

A wall within a wall that is built to provide air space.

Chimney collar

A piece of flashing specifically designed to fit around a vent pipe on the roof deck.

Cladding

A covering or coating material used on an exterior structure.

Closure strip

A strip of metal or foam used to close gaps left in between metal panels.

Coated base sheet

A piece of felt that is soaked in asphalt to make it impermeable to water or moisture.

Cover board

An insulation board made from fibreglass, gypsum, perlite, or wood fibreboard that is used to prevent blistering when foam insulation comes in contact with hot bituminous membranes.

Cricket

A part of the roof structure designed to divert rain water and runoff away from roof projections like chimneys.

Cross ventilation

The effect achieved when warm air is allowed to escape through 1 opening while cool air is allowed to enter through another opening.

Dead level

Completely level; flat.

Dead loads

Permanent weight loads like mechanical or electrical equipment, or structural or architectural components.

Deck

The plywood or wood plank layer of the roof that supports the rest of the roof system.

Deflection

The bowing or sagging that occurs when a structure cannot support the weight placed on it.

Dew point temperature

The dew point is the temperature at which dew forms. When the temperature gets colder than the dew point, condensation occurs.

Dome

An architectural structure shaped like a half-sphere.

Dormer

A raised and framed section of roof that protrudes from the rest of the roof.

Double-gravelling

A double coat of bitumen and aggregate on a built-up roof.

Downspout

A conduit used to move water away from the roof and walls of a building and down to the ground.

Drip edge

Overhanging metal flashing that diverts dripping water away from the roof and sides of a building.

Eaves

The edges of the roof that project past the outer wall.

Edge venting

Part of the ventilation system that allows trapped heat and moisture to escape through small openings along the roof’s edge.

End laps

The area where the ends of rolled roofing materials meet and are overlapped by the next roll.

Exposure

The state of being exposed to the weather.

Fascia

Fascia is a border on low-sloped roofs that is used to protect interior walls from water run-off.

Felt

A sheet of interlocking fibres that is flexible and durable. Can be made from a number of raw materials, such as wood pulp, vegetable fibres (organic), asbestos, glass, or polyester.

Fish-mouthing

Occurs when an edge or seam curves upwards, making a semi-circle shape in the shingle’s edge. Caused by debris that has found its way under the shingle, raised nails, or even wrinkled underlay.

Flashing

Weather-proofing materials used to seal edges and/or gaps at the roof’s perimeter, joints, and seams.

Flashing cement

A special mixture of bitumen and stabilizers used as a high quality sealant around flashing areas.

Flood coat

A thick coat of bitumen used to help embed aggregate on a built-up roof.

Gable roof

A traditional roof style consisting of 2 peaked planes that form a triangle where they meet.

Galvanized steel

Steel that has been coated with zinc in order to make it more resistant to the effects of corrosion.

Granules

Composite material made from crushed stone or gravel that is used for surfacing an asphalt material for UV protection.

Gravel stop

A piece of flashing installed around the perimeter of the roof that stops loose gravel or aggregate from falling off the roof.

Gutter

A channel installed around the edge of the roof that is used to usher runoff water towards the downspout or drains.

Hand-sealing

Used during cold-weather installs or in very high-wind areas, hand-sealing allows roofers to confirm that individual shingles have been properly sealed and to apply added adhesive where needed.

Heat welding

The melting and fusion of overlapping edges of roofing membranes by using high temperatures and pressure.

Hip roof

A sloped roof that rises on all 4 sides to meet at the top. A square hipped roof is shaped like a pyramid, but many hipped roofs are flat at the peak.

Ice dams

An accumulation of ice and snow caused by the combination of blockage in the gutter and hot air escaping from the roof. The heat of the house melts the ice and snow which, because it cannot escape through the gutter, is forced into the roofing system and can result in leaks and major water damage to the surrounding roof and walls.

Infrared thermography

The use of an infrared camera to locate moisture trapped in the roof’s surface.

Inorganic

Materials that are not of animal or plant origin. Not organic.

Insulation

Roofing materials specially designed to trap heat inside a building and keep cold air out.

Interlayment

Typically used with wood shakes, interlayment is a membrane sheet used to improve the weather-proofing and water-shedding abilities of the roof system.

Joist

A small beam used to add extra support to floors, ceilings, or to the roof deck.

Kick-out flashing

Metal flashing used to direct runoff away from the wall.

Lap cement

A special roofing cement made with asphalt that is used to seal and adhere overlapping layers of rolled roof.

Mansard

A decorative steep slope on the perimeter of a roof.

Mats

The backing or base structure of shingles and rolled roof materials.

Membrane

A flexible material used for waterproofing.

Mineral-surfaced roofing

Any roofing material coated in mineral granules.

Miter

An angled cut, or the joint produced when 2 angled cuts meet.

Modified bitumen

Bitumen that has been mixed with a polymer, or the composite sheets made from polymer bitumen.

Mopping

The act of spreading hot bitumen with a roofer’s hand mop.

Nail-pop

When a nail is sticking up out of the roof deck because it wasn’t fully driven in.

Night seal

The material used to protect an unfinished roofing job from water at the end of the work day. It is removed in the morning when work is resumed.

Open valley

When a metal strip is used in the centre of the valley to help direct water runoff away from the shingles and towards the gutters and downspout.

Organic mat

Mat material made from recycled organic matter, usually recycled paper.

OSB

Oriented Strand Board (OSB) is a type of decking made from wood chips and glue.

Overdriven

When a nail or other type of fastener breaks through the roofing material because it was driven in with too much force.

Pan

The flat part between the ribs of a roofing panel.

Parapet wall

The extension of a wall beyond the edge of the roof.

Pitch-pocket or pitch-pan

An enclosure made of sheet metal fitted around a penetration on a roof that is used to seal and weather-proof the surrounding area.

Pliability

A measure of a material’s ability to be flexible or bendable.

Polyvinyl Chloride (PVC)

A synthetic polymer that can be either flexible or rigid. Rigid PVC is used in pipes, while flexible PVC is used to make roof membrane materials.

Ponding

When water accumulates in the low-lying parts of a roof and forms a pond.

Rafter

A structure that is designed to support the roof deck load.

Raggle

A groove cut into a wall for a piece of inset flashing, like a reglet.

Reglet

A metal receiver meant to support the attachment of a piece of counterflashing.

Ridge

The highest point of a roof.

Roof assembly

The sum total of all the roofing components, including the deck, vapour retarder, insulation, and exterior covering.

Roof jack

A metal support bracket used on steep-slope roofs.

Roof slope

The steepness of the line of a roof.

Self-adhering membrane

Membrane that is sold with pre-applied adhesive.

Self-sealing shingle

An asphalt shingle that has pre-applied heat-sensitive adhesive which is activated by the warmth of the sun.

Shading

The appearance of darker or lighter areas on the roof characteristic of newly-installed shingles. A temporary aesthetic issue that usually resolves with weathering.

Shingle

A section of roofing material meant to be applied with enough similar units needed to cover the surface of the roof.

Slate

Used in granular form for roof surfacing, slate is a hard, clay mineral rock.

Spalling

When layers of concrete start to chip or flake off.

Splash block

Part of the water drainage system designed to prevent the water escaping from the downspout from splashing the aggregate in front of the downspout and causing erosion.

Starter course

The very first layer of roofing.

Substrate

The structural deck upon which roofing membrane is applied.

Thermal shock

The stress on roofing materials that results from sudden changes in outdoor temperature.

Toggle bolt

A threaded bolt and expandable clip that can fit through a hole and then provide anchorage from the other side.

Tongue and groove planks

Wood planks cut with corresponding concave and convex grooves so that individual planks join together in perfect alignment. Used in roof decking.

Underdriven

When a nail or fastener isn’t driven in with enough force to make it flush with the surface of the roof deck or shingles.

Underlayments

The materials installed underneath the roofing materials as added protection against water and weather damage.

Valley

An area where 2 angled sections of roof meet and form a “V” shape.

Vapour retarder

A material designed to stop water vapour from penetrating the roofing assembly.

Vent

An opening that allows air, heat, water vapour, or gas to escape from a closed interior space.

Weep holes

Small holes that allow water to drain out from the inside of an architectural component, like a skylight frame or a wall.

Wind uplift

During strong winds, air pressure can build up underneath the roof membrane and cause it to lift away from the roof deck.

Winter curling

In extremely cold weather, the front edge of a shingle contracts and curls up to form a slight “U” shape. Affected shingles then flatten out again once the weather is warmer.

Woven valley

A woven valley is created when the shingles on both sides of the valley are laid in an overlapping pattern.