Roofing contractors glossary

Short, plain-English definitions of the terms you'll meet when choosing a roofing contractor provider in Ontario.

What are 3-tab shingles?: 3-tab shingles are flat asphalt shingles with two cutouts that create three visible tabs per shingle, historically the most economical roofing option in Ontario.
What are architectural shingles?: Architectural shingles are multi-layered asphalt shingles with a laminated design that creates depth and dimension, offering greater durability and wind resistance than traditional 3-tab shingles.
What are starter strip shingles?: Starter strip shingles are a dedicated course of adhesive-backed shingles installed along the roof eave that create a sealed edge and anchor the first row of field shingles above them.
What is a chimney cricket?: A peaked roof structure installed behind a wide chimney to divert water runoff and debris away from the roof surface.
What is a pipe boot?: A pipe boot is a rubber or metal collar that forms a weathertight seal around roof penetrations like plumbing vent stacks, HVAC pipes, or antenna mounts.
What is a ridge vent?: A ridge vent is a continuous exhaust opening installed at the roof peak that allows hot, humid air to escape from the attic, working together with soffit intake vents to create balanced airflow.
What is a roofing square?: A roofing square is a unit of measurement equal to 100 square feet of roof area, used by contractors to calculate material quantities and provide estimates.
What is a TPO membrane?: TPO (thermoplastic polyolefin) is a single-ply synthetic membrane used for flat and low-slope roofs, installed with heat-welded seams and known for high reflectivity.
What is a WSIB clearance certificate?: A WSIB clearance certificate is an Ontario government document confirming that a contractor has maintained valid Workplace Safety and Insurance Board coverage and has no outstanding assessments or liabilities with WSIB.
What is an ice dam?: An ice dam is a ridge of compacted ice that forms at the eave line of a roof, typically caused by heat loss from the attic warming snow, which then refreezes at the colder eave, creating a barrier that traps meltwater and forces it up under roof shingles.
What is attic ventilation balance?: Attic ventilation balance is the correct proportion of soffit intake vents to ridge or gable exhaust vents that allows continuous air circulation through the attic space.
What is drip edge?: Drip edge is a metal flashing installed along the perimeter of a roof that channels water away from the fascia board and prevents water intrusion into the structure.
What is EPDM roofing?: EPDM roofing is a synthetic rubber single-ply membrane commonly applied to flat or low-slope roofs, where seams are sealed and the material is mechanically fastened or fully adhered to the deck.
What is ice and water shield?: A self-adhering synthetic membrane applied to roof decking at eaves, valleys, and penetrations to block water infiltration from ice dams and wind-driven rain.
What is kick-out flashing?: Kick-out flashing is a metal diverter installed where a sloped roof meets an exterior wall, angled to direct water into the gutter system rather than allowing it to run down behind the siding.
What is modified bitumen roofing?: Modified bitumen is asphalt mixed with rubber or plastic polymers and laid in overlapping rolls, creating a flexible, durable roofing membrane for low-slope commercial and residential buildings.
What is roof decking?: Roof decking is the structural layer of plywood or oriented strand board (OSB) fastened to roof rafters that serves as the base for shingles and underlayment installation.
What is roof flashing?: Sheet metal strips installed around roof penetrations and joints to direct water away and prevent leaks at vulnerable seams.
What is roof pitch?: Roof pitch is the steepness of a roof, expressed as the ratio of inches of vertical rise per 12 inches of horizontal run (for example, 4-in-12), which affects material selection and drainage performance.
What is roof underlayment?: Roof underlayment is a water-resistant layer of felt or synthetic material installed over the roof deck, beneath shingles or other roofing material, to provide secondary protection against moisture and extend roof durability.
What is soffit and fascia?: Soffit is the underside of a roof overhang, and fascia is the vertical trim board that closes off the rafter ends at the roofline. Both protect the structure and support gutter systems.
What is standing seam metal roofing?: Standing seam metal roofing is a system of metal panels with raised, interlocking seams and concealed fasteners that lock panels together along their edges.
What is torch-down roofing?: Torch-down roofing is a modified bitumen membrane applied to flat roofs by heating rolled material with a torch until it fuses to the substrate below.
What is valley flashing?: Valley flashing is the metal or membrane lining installed in roof valleys (where two slopes meet) to channel water away and prevent leaks at this vulnerable junction point.