A flat roof in Ottawa typically costs $9 to $18 per square foot installed in 2026, which puts a common 1,000 sq ft flat roof replacement at roughly $9,000 to $18,000. EPDM rubber membrane sits at the affordable end around $9–$13 per sq ft, TPO runs about $11–$16, and two-ply SBS modified bitumen (torch-down) lands near $12–$18 because of the extra labour and materials. Tear-off and disposal of an existing roof adds about $1.50–$3.50 per sq ft, and replacing wet or rotted decking runs $4–$8 per sq ft of affected area. Ottawa's snow load, ice damming, and 60-degree annual temperature swing make ...
Membrane choice is the single biggest line item on a flat roof quote. EPDM — the black rubber sheet most Ottawa homeowners recognize — costs roughly $9–$13 per square foot installed and typically lasts 20–25 years. It is seamless over large areas, forgiving to install, and easy to patch, which is why it dominates residential low-slope work in the city. TPO, a white heat-welded thermoplastic, runs about $11–$16 per square foot; its reflective surface reduces summer heat gain on rooftop patios and...
Localized flat roof repairs — patching a seam, resealing a drain flange, or fixing a flashing detail — usually cost $450–$1,800 in Ottawa. If the membrane is past 18–20 years old or you have more than two or three active leak points, a full replacement is almost always the better spend per year of s...
Most Ottawa quotes assume tearing off the existing roof, and that alone adds about $1.50–$3.50 per square foot depending on how many layers are stacked up. Older homes in Hintonburg, Vanier, and the Glebe often have two or three layers of aging bitumen that must all come off before a new membrane goes down, plus disposal fees at the landfill. Once the deck is exposed, soft or delaminated plywood has to be replaced at roughly $4–$8 per square foot of affected area — a cost no honest contractor ca...
Ottawa asks more of a flat roof than almost any major Canadian city. Ground snow loads in the region are high, so the structure and membrane must handle sustained weight through February and March, and drainage must clear meltwater fast during spring thaw. Repeated freeze-thaw cycling — sometimes several times in a single week — flexes seams and works water into any gap that isn't fully sealed, which is why heat-welded or fully adhered systems outperform cheap mechanically fastened jobs here. Su...
If water sits on your roof more than 48 hours after rain, the slope or drains are inadequate. Fixing ponding with tapered insulation during replacement costs far less than repeated leak repairs and interior drywall damage later.
A straight like-for-like flat roof re-cover or replacement on a house generally does not require a City of Ottawa building permit, but a permit is typically needed when you alter the structure — changing the roof deck, adding a rooftop deck or terrace, modifying the slope, or converting the roof assembly. If your project touches structure or creates occupiable rooftop space, confirm with the City before work starts, because unpermitted structural changes create real problems at resale and with i...
Get three itemized written quotes and insist each one states the same details: membrane type and thickness in mils, number of plies, attachment method (fully adhered, mechanically fastened, or torch-applied), insulation type and R-value, number of existing layers being removed, decking replacement rate per sheet, flashing and drain scope, and both the manufacturer material warranty and the contractor's workmanship warranty. A 10-year workmanship warranty from an established Ottawa company is wor...
Flat roofing in Ottawa runs roughly April through November, with adhesives and torch work needing above-freezing temperatures. Booking in late winter for a spring slot often gets better pricing than calling during the August peak.
In 2026, a flat roof in Ottawa costs about $9–$18 per square foot installed, so a 1,000 sq ft roof runs roughly $9,000–$18,000. EPDM is about $9–$13 per sq ft, TPO $11–$16, and two-ply SBS modified bitumen $12–$18. Tear-off adds $1.50–$3.50 per sq ft.
A properly installed 60-mil EPDM or TPO membrane typically lasts 20–25 years in Ottawa, and two-ply SBS modified bitumen often reaches 25–30 years. Freeze-thaw cycling and ponding water shorten that lifespan significantly, which is why proper slope to drain matters so much locally.
EPDM costs less and handles extreme cold and movement very well, making it the most common residential choice in Ottawa. TPO costs more but has heat-welded seams and a reflective white surface that reduces summer heat gain, which suits rooftop terraces and additions with living space directly below.
A like-for-like membrane replacement usually does not require a City of Ottawa building permit. A permit is generally required if you change the roof structure or deck, alter the slope, or add a rooftop deck or terrace. Confirm with the City before any structural work begins.
Localized flat roof repairs such as seam patching, drain resealing, or flashing fixes typically cost $450–$1,800 in Ottawa. If the membrane is over 18–20 years old or leaking in multiple places, replacement usually delivers better value per year of service.