--- title: "Flat Roof Repair in Sarnia, ON | flat-roof-repair.ca" description: "Flat roof leak repair, replacement and maintenance in Sarnia, Ontario, for houses, condos and commercial buildings. Drains and flashings for heavy summer storms." url: https://flat-roof-repair.ca/locations/sarnia/ last_updated: 2026-10-23 --- # Flat roof repair in Sarnia We repair, replace and maintain flat roofs in Sarnia: 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 Sarnia Much of Sarnia'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. 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/). ## Chemical Valley, the harbour and the North End in Sarnia Sarnia grew with oil, the railways of the late 1850s and lumber, and it became a city in 1914. During the Second World War the Polymer Corporation brought synthetic rubber to the city, and Chemical Valley south of downtown now holds refineries and chemical plants. The grain elevator at the harbour dates to 1927. Census data shows about 71% of homes were built before 1981. With most homes older than 1981, neighbourhoods such as the North End and the streets south of Highway 402 often have bungalows and houses with flat-roofed additions. Lambton Mall and the retail strips carry wide low-slope roofs, as do industrial service buildings, warehouses and maintenance shops tied to the plants. About 36% of homes pre-date 1961, and buildings of that age often have layers of old roofing under the top surface, which affects how repairs are planned. ## Sarnia 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 Sarnia has to handle. - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** ## Homes and buildings in Sarnia The age and type of buildings shape the flat roofs we see. These are the 2021 Census figures for Sarnia. - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** - **undefined** ## Sarnia: facts for property owners - Population of Sarnia: 72,047 (2021 Census). ([source](https://en.wikipedia.org/wiki/List_of_municipalities_in_Ontario)) - Sarnia is part of the Lambton County. - City: replacing stucco, siding or shingles with the same material usually needs no permit. ([source](https://www.sarnia.ca/construction-projects-and-renovations/building-permits/)) > Before summer storm season, look at the drains and scuppers on your roof from a safe spot or in photos. Leaves and grit in a drain basket are the most common cause of water backing up under flashings. ## Starting prices in Sarnia | 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 Sarnia - [Garages and additions](https://flat-roof-repair.ca/property-types/garages-and-additions/) - [Houses](https://flat-roof-repair.ca/property-types/houses/) - [Townhouses and row houses](https://flat-roof-repair.ca/property-types/townhouses-and-row-houses/) - [Condo buildings](https://flat-roof-repair.ca/property-types/condo-buildings/) - [All property types](https://flat-roof-repair.ca/property-types/) ## Nearby cities - [London](https://flat-roof-repair.ca/locations/london/) - [Windsor](https://flat-roof-repair.ca/locations/windsor/) - [Woodstock](https://flat-roof-repair.ca/locations/woodstock/) - [Southwestern Ontario](https://flat-roof-repair.ca/locations/southwestern-ontario/) ## Flat roofs in Sarnia: questions **How much does flat roof repair cost in Sarnia?** A small leak repair starts from $350 per repair and a new house flat roof starts from $8,000 per roof. Prices in Sarnia depend on access, layers to remove and the membrane. See [pricing](https://flat-roof-repair.ca/pricing/). **What causes most flat roof leaks in Sarnia?** 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 Sarnia?** City: replacing stucco, siding or shingles with the same material usually needs no permit. That wording is about shingles, so ask how it applies to a flat roof membrane. Rules can change, so confirm with the building department before you start. See [re-roofing permits in Ontario](https://flat-roof-repair.ca/guides/re-roofing-permits-ontario/). **My Sarnia 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 Sarnia?** Yes, including London, Windsor, Woodstock and the rest of southwestern Ontario. See [Southwestern Ontario](https://flat-roof-repair.ca/locations/southwestern-ontario/). ## Related - [Flat roof repair in Southwestern Ontario](https://flat-roof-repair.ca/locations/southwestern-ontario/) - [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/ ยท Email: info@flat-roof-repair.ca