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Glossary Terms

Glossary  of Roofing Terms

At Century Roofing Limited, we hope to educate our homeowners on any terms undefined. We’ve compiled a handy list of some of the most common roofing terms so that you can understand every step of the roofing process.

  • Absorption

    The process by which one material is permeated by another material like liquid, gas or moisture.
  • Aggregate

    Aggregate is usually made up of rock, stones, crushed stones, gravel or marble chips and is used for roof surfacing.
  • Alligatoring

    Cracking occurring on surface bitumen that closely resembles alligator skin.
  • Apron flashing

    The flashing that covers the juncture of the top of a sloped roof and a vertical wall or adjoining roof.
  • Asphalt

    A mix of sand or gravel and bitumen that is used for surfacing roads and roofs.
  • Asphalt felt

    Asphalt-soaked felt used as underlay beneath other roofing materials. Asphalt felt provides an added layer of protection against water and moisture damage.
  • Back surfacing

    Fine, granular material added to the backs of shingles to keep them from sticking together.
  • Ballast

    A heavy material that is used as an anchor to hold roof membranes in place.
  • Base flashing

    Roof membrane material that protects the joints between the roof and adjoining walls, or other vertical surfaces, from exposure to water and weather.
  • Base ply

    The lowest ply of roofing material in the roofing system.
  • Base sheet

    Asphalt-coated felt that is used as the first ply in certain roof systems.
  • Batten

    Thin strips of wood used to provide a fixed point to which other roofing materials, like shingles or tiles, can be attached.
  • Bitumen

    A naturally occurring black viscous material made up of decomposed organic materials and hydrocarbons that is used for roof surfacing.
  • Built-up roof membrane

    A multi-layered roof membrane made up of alternating layers of felts, fabrics or mats and bitumen.
  • Butt flashing

    The butt flashing is a metal strip used to keep water from seeping into the upper edges of the membrane base flashing, wall flashing or primary flashing.
  • Butyl

    A rubber-like material that is used as a sealant or adhesive.
  • Butyl tape

    A preformed sealant tape that is used to close joints and seams.
  • Canopy

    A part of the roof structure that overhangs an entrance or a door.
  • Cant Strip

    A three-sided strip of wood cut on an angle to provide a sloped transition between the roof deck and an adjacent wall. Cant strips help with waterproofing by closing the gap between the roof deck and any walls.
  • Cap Flashing

    Cap flashing is a form of flashing that keeps water from getting into the upper edges of the membrane base or other types of flashing.
  • Cap Sheet

    Used in built-up roofing, a cap sheet is the topmost roofing sheet that serves to protect the lower layers of a roof membrane. It’s usually coated with a granular substance and can help to extend the life of the roof.
  • Closed Valley

    A valley is the line where two separate sections of the roof meet and drain water off the roof. A closed valley is when the shingles on one side completely cover the shingles on the other side.
  • Closure Strip

    A strip of metal or other material that is used to close gaps in between membranes or other joints.
  • Coping

    A piece of metal, masonry or stone that is used to protect the top of part of a wall from weather and water.
  • Counter flashing

    A shaped piece of metal sheeting that is used to cover and weatherproof the upper edge of the base flashing.
  • Cupola

    A small roofed structure that sits on top, usually in the center, of a larger roofed structure.
  • Cupping

    When shingles start to warp at the edges, forming a cup shape. Cupping is usually a sign that shingles contain a manufacturer’s defect or were installed incorrectly.
  • Deck

    An important structural component of the roof. The deck supports the weight of the rest of the roofing system.
  • Double gravelling

    The process of applying two layers of bitumen and aggregate to a built-up roof.
  • Downspout

    A pipe that is used to divert runoff water towards the ground or the storm drain.
  • Drip edge

    A custom sheet of metal designed to extend shingles beyond eaves and gutters so that water can’t get behind the fascia board.
  • Eave

    The part of the roof that extends beyond the exterior walls of the house.
  • Expansion joint

    An assembly between two building elements that is designed to allow free movement between the elements without damage to the roofing or waterproofing system.
  • Extrusion

    A manufacturing process used to make some types of single-ply roofing membranes.
  • Eyebrow

    Either a small dormer with an arched roof line or a small shed roof projecting from the main roof.
  • Fascia

    The vertical band is either wood or aluminum and covers the ends of the rafters or trusses, it goes behind the eavestrough and up the gable ends to provide waterproofing protection for the building’s interior.
  • Ferrule

    A metal sleeve that is placed inside a gutter at the top that protects and preserves the gutter’s original shape.
  • Flange

    A rim or collar that is used to both strengthen and attach a rigid component to the roofing structure.
  • Flashing

    As part of a weather-barrier system, flashing refers to the components used to seal the roof system at its edges to prevent water from soaking through the roof and causing damage.
  • Gable

    The triangular part of an exterior wall of a building that sits under the sloping roof but above the eaves and that encloses the end of a pitched roof.
  • Gambrel

    A two-sided roof with two pitches on each side with a shallow slope above a steeper one.
  • Gravel stop

    A gravel stop is a type of metal edge flashing that is installed around the perimeter of the roof to provide an edge for the roofing material.
  • HEX shingles

    Hex shingles have a hexagonal shape after installation is complete.
  • Hip

    The edge created by the intersection of two sloping roof planes.
  • Hip Roof

    A roof with no gables or vertical slides; all of the sides on a hip roof gently slope towards the walls.
  • Hoist

    A mechanical device used for lifting or lowering a heavy load.
  • HVAC

    HVAC stands for Heating, Ventilating, and Air Conditioning units or equipment.
  • Ice Dam

    A block of ice formed by refreezing meltwater at the overhang of a steep roof. When ice blocks the gutters, it is impossible for meltwater to escape, which then results in excess water leaking underneath roofing materials and into the building.
  • Impact resistance

    The ability of the roofing assembly to resist external damage.
  • Infrared thermography

    Also called thermal imaging, infrared thermography is a part of a roof system analysis used to locate the presence of moisture and leaks.
  • Intake ventilation

    The intake vent is the part that draws fresh air into the roof’s ventilation system.
  • Interlocking shingles

    A method of interlocking individual shingles to increase the wind resistance of the roof system.
  • Joist

    The metal or wood beams that are arranged parallel from wall to wall and are used to support a floor, ceiling, or roof of a building.
  • Laminated shingles

    Stronger and more decorative than other shingles, laminate shingles are made up of two pieces of shingle that are laminated together to create strength and durability.
  • Lap cement

    An asphalt-based cement that is used to adhere roll-roofing materials together.
  • Loose-laid membranes

    Held in place with a ballast, loose-laid membranes are only attached to the substrate at the perimeter of the roof.
  • Mansard Roof

    Also called a French roof, a mansard roof is a steep, four-sided gambrel-style hip roof that terminates into a flat roof at its high point.
  • Membrane

    A pliable sheet that serves as the waterproofing component in a roofing or waterproofing assembly, and whose primary function is to keep water from penetrating the roof.
  • Neoprene

    A synthetic, rubber-like material that is used in roof membranes or flashings as a weatherproofing agent.
  • Nesting

    A re-roofing method where new shingles are laid over the top of old shingles with the edge of the new shingle being butted against the bottom edge of the old shingle tab.
  • Open Valley

    A roofing method that leaves the valley flashing exposed and free of shingles to allow water to run off down the opened valley.
  • Parapet Wall

    The part of a perimeter wall that runs along the edge of the roof.
  • Perlite

    An aggregate that is used in lightweight, insulating concrete and preformed insulation boards.
  • Pitch-pocket (Pitch-pan)

    An enclosure fashioned out of sheet metal and sealed with grout and bitumen that is used to patch a roof penetration.
  • Puncture resistance

    The extent to which a material can resist puncture or perforation.
  • Purlin

    The horizontal secondary structural member in a roof frame that supports loads from the primary structural framing.
  • Reinforced membrane

    Roofing membrane that has been strengthened with fibres, mats, sheeting or other reinforcement materials.
  • Release tape

    A sheet of plastic applied to the back of self-sealing shingles to prevent them from sticking together.
  • Roofing tape

    Asphalt-saturated tape that is used in conjunction with asphalt cements for flashing and repairing asphalt roofing.
  • Saddle

    Located between drains, or in a valley, a saddle is a slightly raised structure that is used to direct surface water off the roof.
  • Self-adhering membrane

    Protected by release paper, a self-adhering membrane is coated with adhesive and can adhere to a substrate without the application or use of any additional adhesive.
  • Soffit

    The enclosed underside of any architectural structure such as a roof eave.
  • Soil stack

    Part of the plumbing system, a soil stack is a sanitation pipe that penetrates the roof and is used to vent gases out of the building.
  • Step flashing

    Individual pieces of flashing that are overlapped and “stepped” on a vertical surface. Used around chimneys and other projections on the roof.
  • Substrate

    Usually the roofing deck. The substrate is the underlying surface upon which the roofing membrane is applied.
  • Test Cut

    A sample cut out of the roof that is used to examine all of the components of the roofing membrane and determine if there are any issues with the membrane.
  • Thermal Shock

    The contraction of the membrane that can occur when it is exposed to rapid changes in temperature.
  • Underlayment

    Underlayment is used to add a layer of weather and waterproofing to the roof deck. It is a synthetic felt in varying weights and surface finish, installed between the roof deck and the rest of the roof system.
  • Valley

    The ‘V’ shaped depression that is formed by the intersection of two sloping sections of roof. The valley provides a channel for water to run off the roof.
  • Vapor Retarder

    Any material that is used to damp-proof, or restrict the passage of water vapor through a roof system.
  • Waterproof underlayment

    Waterproof underlayment is designed to seal the roof deck and provide extra waterproofing for areas susceptible to leaks.
  • Wind Uplift

    Wind uplift is caused by the deflection of the wind at the roofs edges. During very strong winds, wind uplift can result in the membrane pulling away from the deck.
  • Woven valley

    The valley flashing is not exposed in this method of valley construction, but rather, the shingles on both sides of the valley are woven together in an overlapping pattern.

What are people saying about

Century Roofing

Century Roofing will ensure that each client is happy with their new roofing and/or siding project. We encourage our clients to provide us with feedback on their projects.

Here are some kind works that some of our clients have to say about working with our team.

  • We had a fantastic experience with Century Roofing. They took care of all our insurance work after a storm. Any... read more

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    I am satisfied with the work carried by Century Roofing. I was kept well informed of all the tasks they... read more

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  • Century Roofing did a fantastic job at a very reasonable price. I am very happy that I found them for... read more

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    I am pleased to see the dedication of Century Roofing to provide the best and satisfactory roofing services in Calgary... read more

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  • We experienced a leak in our roof and then we contacted Century Roofing for roof repairs. The staff at Century... read more

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    After the crazy storms this year we hired Century Roofing for a roof replacement. They were very affordable and did... read more

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  • I was just surprised to see that how quick the Century Roofing staff is. Whether it is just consultation or... read more

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    I had hired Century Roofing for the installation of a new roof at our home in Springbank. They team did... read more

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  • We had Century Roofing out to fix our roof from the 2013 Airdrie hail storm (fixed in August 2014) and... read more

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    Excellent professional advice, prompt and solid work

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  • Ethical.respectful.knowledgeable. dependable. And most importantly trustworthy.

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    Completely satisfied with their work and cost. We used Century Roofing for another home of ours and were very pleased.... read more

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