--- title: "Flat Roof Repair in St. Catharines, ON | flat-roof-repair.ca" description: "Flat roof leak repair, replacement and maintenance in St. Catharines, Ontario, for houses, condos and commercial buildings. Leak repair, repairs and replacement." url: https://flat-roof-repair.ca/locations/st-catharines/ last_updated: 2026-10-23 --- # Flat roof repair in St. Catharines We repair, replace and maintain flat roofs in St. Catharines: houses, garages and additions, condo and apartment buildings, plazas, offices and warehouses. Send photos and a few details for a written quote. ## Flat roof services in St. Catharines Much of St. Catharines's housing is older, and older houses often have flat roofs over rear additions, porches and garages. Typical signs are a stain on the kitchen ceiling, water at a skylight or a roof with several worn layers. 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](https://flat-roof-repair.ca/services/flat-roof-replacement/) with EPDM, TPO, PVC or modified bitumen, and fix the [drainage](https://flat-roof-repair.ca/services/roof-drains-and-scuppers/) so water does not sit on the new membrane. Owners and property managers also book [inspections](https://flat-roof-repair.ca/services/flat-roof-inspection/) and [maintenance visits](https://flat-roof-repair.ca/services/flat-roof-maintenance/). ## Canal city: St. Catharines from Port Dalhousie to Western Hill St. Catharines grew around the first Welland Canal, built from 1824 to 1833, which made it a commercial and industrial hub for the Niagara Peninsula. It became a city in 1876. Postwar growth was explosive: population rose from 37,984 in 1951 to 84,472 in 1961, and the city annexed Grantham Township, Merritton and Port Dalhousie. General Motors of Canada was long its largest employer. Census data show about 71% of homes were built before 1981 and 33% before 1961. Downtown, Port Dalhousie, Merritton and the North End have older brick buildings and houses where flat roofs over rear additions and storefronts are common. The western neighbourhoods such as Western Hill and Glenridge, and annexed Grantham, reflect the postwar expansion, when schools, apartment blocks and plazas with low-slope roofs were built. The Pen Centre is a large regional shopping centre, and the city has about 140 industrial buildings, including the former GM plant lands. With so much older housing and so few homes built since 2001 (about 10%), roofs of an older vintage are a large part of the city. ## St. Catharines 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 St. Catharines has to handle. - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** ## Homes and buildings in St. Catharines The age and type of buildings shape the flat roofs we see. These are the 2021 Census figures for St. Catharines. - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** ## St. Catharines: facts for property owners - Population of St. Catharines: 136,803 (2021 Census). ([source](https://en.wikipedia.org/wiki/List_of_municipalities_in_Ontario)) - St. Catharines is part of the Regional Municipality of Niagara. - Flood Alleviation Program (FLAP): Rebate up to 90% of eligible costs, max $5,000, for single/semi-detached homes built before 2012 (backwater valves, weeping tile disconnection to sump pump). ([source](https://www.stcatharines.ca/water-utilities-and-services/basement-flooding/)) > Look at the ceiling under a flat roof after the first big thaw and after heavy rain. A new stain is easier and cheaper to trace early. ## Starting prices in St. Catharines | Item | Starting price | |---|---| | [Small leak repair (patch, seam or puncture)](https://flat-roof-repair.ca/services/flat-roof-leak-repair/) | from $350 per repair | | [Small flat roof replacement (garage, porch or addition)](https://flat-roof-repair.ca/property-types/garages-and-additions/) | from $4,000 per roof | | [House flat roof replacement (about 1,000 sq ft)](https://flat-roof-repair.ca/property-types/houses/) | from $8,000 per roof | 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](https://flat-roof-repair.ca/pricing/). ## Roofs we work on in St. Catharines - [Garages and additions](https://flat-roof-repair.ca/property-types/garages-and-additions/) - [Apartment buildings](https://flat-roof-repair.ca/property-types/apartment-buildings/) - [Houses](https://flat-roof-repair.ca/property-types/houses/) - [Townhouses and row houses](https://flat-roof-repair.ca/property-types/townhouses-and-row-houses/) - [All property types](https://flat-roof-repair.ca/property-types/) ## Nearby cities - [Niagara Falls](https://flat-roof-repair.ca/locations/niagara-falls/) - [Welland](https://flat-roof-repair.ca/locations/welland/) - [Hamilton](https://flat-roof-repair.ca/locations/hamilton/) - [Hamilton and Niagara](https://flat-roof-repair.ca/locations/hamilton-niagara/) ## Flat roofs in St. Catharines: questions **How much does flat roof repair cost in St. Catharines?** A small leak repair starts from $350 per repair and a new house flat roof starts from $8,000 per roof. Prices in St. Catharines depend on access, layers to remove and the membrane. See [pricing](https://flat-roof-repair.ca/pricing/). **What causes most flat roof leaks in St. Catharines?** Details more than the open membrane: seams, parapet and wall flashings, drains, vents and skylights. See [flashing leaks](https://flat-roof-repair.ca/problems/flashing-leaks/) and [clogged drains](https://flat-roof-repair.ca/problems/clogged-drains/). **Do I need a permit to replace a flat roof in St. Catharines?** Check with the St. Catharines building department. Replacing the membrane alone is often treated differently from structural work, a new rooftop deck or added weight. See [re-roofing permits in Ontario](https://flat-roof-repair.ca/guides/re-roofing-permits-ontario/). **My St. Catharines house is older. Can the flat roof go on over the old one?** Sometimes one new layer can go over one old layer, but on older houses we often find two or three layers already, wet insulation or soft deck boards. Then a full tear-off is the safer choice. See [repair or replace](https://flat-roof-repair.ca/guides/repair-or-replace-flat-roof/). **Do you also work near St. Catharines?** Yes, including Niagara Falls, Welland, Hamilton and the rest of Hamilton and Niagara. See [Hamilton and Niagara](https://flat-roof-repair.ca/locations/hamilton-niagara/). ## Related - [Flat roof repair in Hamilton and Niagara](https://flat-roof-repair.ca/locations/hamilton-niagara/) - [Flat roof leak repair](https://flat-roof-repair.ca/services/flat-roof-leak-repair/) - [Flat roof replacement](https://flat-roof-repair.ca/services/flat-roof-replacement/) - [Finding a flat roof leak](https://flat-roof-repair.ca/guides/finding-a-flat-roof-leak/) --- Get a quote: https://flat-roof-repair.ca/request-a-quote/ · Email: info@flat-roof-repair.ca