Flat roof repair in Toronto

Flat roof services in Toronto

Toronto has many mid- and high-rise buildings, whose flat roofs are managed by condo boards and property managers. The usual work is drains, flashings at mechanical units and planned replacements. Its design snow load is among the lightest of the cities on this site, so freeze–thaw and summer storms do more damage than snow weight. We find where the water gets in, fix that spot and tell you how much life the rest of the roof has.

When a roof is past repair, we replace it with EPDM, TPO, PVC or modified bitumen, and fix the drainage so water does not sit on the new membrane. Owners and property managers also book inspections and maintenance visits.

Rowhouse streets, converted factories and tower blocks in Toronto

Toronto grew in layers. The town of York was founded in 1793, and by the late 1800s rail and port facilities pulled industry onto the waterfront, where it stayed for about a century. That legacy shows in areas such as Corktown, Leslieville and the Distillery District, where former industrial buildings sit beside Victorian houses. Census figures say about 58% of the city's dwellings were built before 1981 and roughly 29% before 1961.

In older neighbourhoods like Cabbagetown and the Annex you often find a flat or low-slope roof over a rear kitchen addition or a porch on a brick house. The population doubled between 1951 and 1971, and that postwar building left many low-rise plazas, schools and apartment blocks with membrane or built-up flat roofs. In the Port Lands and other industrial pockets, large commercial and warehouse buildings add a different scale of low-slope roofing. Nearly half of homes are in apartment buildings of five storeys or more, so roof access and drainage are often a building-management matter.

Toronto weather and your flat roof

Ontario's Building Code sets the climate values used to design roofs in each municipality. They show what a flat roof in Toronto has to handle. Figures are for Toronto City Hall; SB-1 lists Etobicoke, North York and Scarborough separately with similar values.

• 0.9 kPaGround snow load (about 19 lb per sq ft)
• 0.4 kPaRain load added to snow (Sr)
• 25 mmRain in a 15-minute storm (design value)
• 97 mmRain in one day, 1-in-50-year storm
• -18 °CJanuary design temperature
• 3,520Heating degree-days per year
• 0.44 kPaHourly wind pressure, 1-in-50-year

Snow loads are lower than in most of Ontario, but freeze–thaw cycles still open tired seams and flashings, and ice can block drains in late winter.

A design storm can drop 25 mm of rain in 15 minutes. On a flat roof that water has to reach a drain or scupper quickly, so clear drains and sound drain flashings matter as much as the membrane.

Environment and Climate Change Canada climate normals (1991–2020) record about 122 cm of snowfall a year at the Toronto station.

Source: Ontario Building Code, Supplementary Standard SB-1, Table 1.2

Homes and buildings in Toronto

The age and type of buildings shape the flat roofs we see. These are the 2021 Census figures for Toronto.

• 58%Homes built before 1981
• 24%Homes built since 2001
• 29%Detached and semi-detached houses
• 5%Row houses and townhouses
• 47%Apartments in buildings of 5+ storeys
• 48%Households that rent

47% of homes in Toronto are apartments in buildings of five or more storeys. Those roofs are looked after by condo boards and property managers, who need a written scope, photos and a plan that fits the reserve fund. See condo buildings and apartment buildings.

48% of households in Toronto rent. Landlords and property managers can send photos and the tenant's description of the leak, and we reply with the scope and a quote by email. See apartment buildings.

Source: Statistics Canada, 2021 Census Profile

Storms that hit Toronto

• 8 July 2013: Two thunderstorm systems merged on 8 July 2013 and caused widespread flooding and power outages in Toronto, with up to 126 mm of rain in about 90 minutes. Source
• December 2013: A major ice storm struck Toronto in December 2013, with a second, stronger wave of freezing rain in the early morning of 22 December. Source

Storms like these are when blocked drains, loose flashings and open seams show up. After a big storm, check the ceilings under the roof and send us photos of any new stain.

Toronto: facts for property owners

• Population of Toronto: 2,794,356 (2021 Census). Source
• City of Toronto: no building permit is needed for 'replacing existing roofing material provided no structural work is required'; permits are needed for structural work and for green roofs / rooftop stormwater retention systems. Source
• Mandatory Downspout Disconnection Program: City program requiring connected downspouts to be disconnected; financial assistance up to $500 for eligible low-income seniors / persons with disabilities. Source
• Basement Flooding Protection Subsidy Program: Expanded May 1, 2026: up to $6,650 per property for assessment, backwater valves, sump pump, and severance/capping of storm or weeping-tile connections. Source
• Eco-Roof Incentive Program: Applications open: green roof $100/m² (up to $100,000), cool roof $5/m² for new membrane or $2/m² for coating over existing roof (up to $50,000); apply before starting roof work. Source
• Toronto Green Roof Bylaw: City bylaw requiring green roofs on new buildings above a gross floor area threshold. Source

Rules and programs change. Confirm current details with the municipality before you start work.

Starting prices in Toronto

Starting prices in CAD before 13% HST, based on typical Ontario contractor rates (mostly Toronto and the GTA). The final price depends on roof size, access, the layers to remove, the membrane, drains and flashings, and is confirmed in your written quote.

See all prices.