Flat roofs fail at the seams, not the surface.
EPDM, TPO, and modified bitumen repair across the GTA. Same-day for active leaks.
Flat roof failures we diagnose and fix.
Every membrane system fails differently. We know all three, and we use the right material for each.
Membrane Splits & Blistering
Lap Seam Failures
Ponding Water & Drain Blockage
Parapet & Edge Flashing
HVAC Curb Flashing
Emergency Tarping & Make-Safe
Membrane Splits & Blistering
EPDM · TPO · Mod-Bit
Blistering traps moisture and accelerates failure. We cut, dry, and re-bond with system-matched material.
Lap Seam Failures
Most common flat roof leak
TPO seams, EPDM laps, and Mod-Bit overlaps all fail over time. We re-weld or re-adhere and test.
Ponding Water & Drain Blockage
Standing water assessment
When drains block or membrane settles, water ponds. We clear drains, re-slope, and repair the saturated zone.
Parapet & Edge Flashing
Perimeter failure points
Where the membrane meets a parapet or edge, water gets in. Coping caps and through-wall flashings must be watertight.
HVAC Curb Flashing
Rooftop penetrations
The most neglected repair on commercial flat roofs. We re-flash, re-caulk, and seal all mechanical penetrations.
Emergency Tarping & Make-Safe
Active leak response
When water is coming through right now, a tarp is the first move. We tarp, document, and schedule permanent repair.
Flat roof leaking in the GTA? We're on-site same day, commercial and residential.
Why Blue Knight fixes it right when others patch and leave.
All three membrane systems
Written scope before we touch anything
Commercial and residential
Winter-capable repairs
Drain-to-drain assessment
All three membrane systems
We work across all three, never the wrong patch material for the wrong system.
Written scope before we touch anything
We photograph every defect and give you a written estimate before any work begins.
Commercial and residential
From a garage roof to a 40,000 sq ft commercial strip, every flat roof problem in the GTA.
Winter-capable repairs
We use cold-weather sealants and torched systems that work at -10°C. No waiting for spring.
Drain-to-drain assessment
We walk the full surface, every drain, seam, and penetration, not just the visible failure.
“The seam looks fine until it isn't. We find the other two before they become emergencies.”
“The seam looks fine until it isn't. We find the other two before they become emergencies.”
Rated 5 out of 5Blue Knight was, by far, the best. Responsive, ethical, totally professional — and their crew went above and beyond at no extra charge.
Rated 5 out of 5They installed a full new roof in one day. The crew worked around the house without us hardly knowing they were there.
Rated 5 out of 5I emailed at 4 a.m. and spoke with someone that same day. Estimate and completed work all within one day. Pricing was fair, work was excellent.
I emailed at 4 a.m. and spoke with someone that same day. Estimate and completed work all within one day. Pricing was fair, work was excellent.
Blue Knight was, by far, the best. Responsive, ethical, totally professional — and their crew went above and beyond at no extra charge.
They installed a full new roof in one day. The crew worked around the house without us hardly knowing they were there.
Luciano did not try to sell me a new roof. Appreciated the honesty — he showed up when he said he would.
We had a leak diagnosed by two other contractors who could not find the source. Blue Knight found it on the first visit and fixed it the same week.
Flat roof replacement on a commercial unit. Clean, fast, no surprises on the invoice. The crew left the site cleaner than they found it.
Called after a storm damaged our roof. Someone was on site within hours, tarped everything, and had us fully repaired before the next rain.
Had a slow basement leak for years. Every other company just caulked it. Blue Knight found the actual source and did a proper waterproofing job. No issues since.
Our neighbours recommended them for a valley repair. Small job, but they treated it like it mattered — showed up on time, matched the shingles perfectly, and charged exactly what they quoted.
Featured Projects.
Rooftops across the GTA.
From downtown Toronto to the 905 and beyond, one crew, one warranty, twenty-five years of GTA rooflines.
Service availability may vary. Call (647) 383-8664 to confirm coverage for your area.
Rooftops across the GTA.
From downtown Toronto to the 905 and beyond, one crew, one warranty, twenty-five years of GTA rooflines.
Service availability may vary. Call (647) 383-8664 to confirm coverage for your area.
Flat roof repair questions.
Most residential flat roof repairs range from $450 to $3,500. A blocked drain or minor seam repair runs $450-$900. Replacing a failed membrane section or re-flashing a parapet typically runs $1,200-$3,500. We provide a written estimate before starting.
EPDM membranes last 20-30 years with proper maintenance. TPO runs 20-25 years. Modified bitumen is typically 15-20 years. Toronto's freeze-thaw cycle shortens all of these, an annual post-winter inspection adds years to any flat roof's life.
Yes, with the right materials. We use cold-temperature-rated adhesives and torch-applied systems that bond reliably down to -10°C. Emergency repairs happen year-round. Elective work is sometimes better scheduled for spring when temperatures allow full-strength bonding.
Failed lap seams are the single most common cause, followed by cracked parapet flashing and deteriorated pipe boot seals. Toronto's freeze-thaw cycles stress every seam and penetration every winter. Blocked drains that let water pond accelerate membrane failure significantly.
If the failure is isolated to one zone and the rest of the membrane is sound, repair is the right call. If more than 20-25% of the surface has failed seams or blistering, or if the membrane is past its design life, replacement gives better long-term value. We assess the entire roof before making any recommendation.
What GTA Property Owners Ask About Flat Roof Repairs.
The most-searched questions, answered by 25-year GTA flat roofing specialists.
Most residential flat roof repairs in the GTA run $450-$2,500. Drain cleaning and minor seam patches sit at the low end ($450-$800). Larger membrane section replacements or parapet re-flashing typically run $1,200-$2,500. We give a written estimate with photos before any work begins, and the figure does not change afterwards.
Insurance covers sudden damage from a covered peril, storm, hail, wind, or a fallen object. Gradual membrane deterioration or maintenance-related failures are excluded. If a storm event caused or worsened a seam failure, document it immediately; we write inspection reports suitable for insurance claims. The faster you file, the stronger your case.
Repair makes financial sense when the damage is isolated and the surrounding membrane still has life. When more than 20-25% of the surface shows active failures, or the membrane is 20+ years old, patchwork becomes a cycle of diminishing returns. A new TPO or EPDM membrane runs $8-$20 per sq ft installed, replacement often pencils out over a 5-year horizon.
TPO has become the go-to for new commercial installs in the GTA, it handles freeze-thaw cycling well, reflects summer heat, and heat-welded seams are more durable than EPDM adhesive laps. EPDM remains excellent for residential applications. Modified bitumen is still widely used for re-roofing over existing systems. The 'best' material depends on the structure, slope, and existing deck.
- How much does it cost to repair a flat roof in Toronto?
- Most residential flat roof repairs in the GTA run $450-$2,500. Drain cleaning and minor seam patches sit at the low end ($450-$800). Larger membrane section replacements or parapet re-flashing typically run $1,200-$2,500. We give a written estimate with photos before any work begins, and the figure does not change afterwards.
- Is flat roof repair covered by home insurance in Ontario?
- Insurance covers sudden damage from a covered peril, storm, hail, wind, or a fallen object. Gradual membrane deterioration or maintenance-related failures are excluded. If a storm event caused or worsened a seam failure, document it immediately; we write inspection reports suitable for insurance claims. The faster you file, the stronger your case.
- When does flat roof repair stop making sense versus replacement?
- Repair makes financial sense when the damage is isolated and the surrounding membrane still has life. When more than 20-25% of the surface shows active failures, or the membrane is 20+ years old, patchwork becomes a cycle of diminishing returns. A new TPO or EPDM membrane runs $8-$20 per sq ft installed, replacement often pencils out over a 5-year horizon.
- What is the best flat roof material for Toronto's climate?
- TPO has become the go-to for new commercial installs in the GTA, it handles freeze-thaw cycling well, reflects summer heat, and heat-welded seams are more durable than EPDM adhesive laps. EPDM remains excellent for residential applications. Modified bitumen is still widely used for re-roofing over existing systems. The 'best' material depends on the structure, slope, and existing deck.
- What is the difference between EPDM, TPO, and modified bitumen roofing?
- EPDM is a synthetic rubber sheet typically glued or mechanically fastened, durable, black, and UV-stable. TPO is a white thermoplastic membrane that is heat-welded at seams, popular for energy savings. Modified bitumen is an asphalt-based system installed in layers with a torch or cold adhesive, common on older Toronto commercial buildings. Each has different repair techniques; never use the wrong patch material.
- Can you repair a flat roof without knowing what membrane type it is?
- We identify the membrane before we touch anything. Using incompatible patch material, gluing an EPDM patch onto a TPO field, for instance, creates a worse failure than the original. Our assessment starts with system identification from product markings, seam style, and material feel. Most 25-year-old GTA roofs are modified bitumen; most post-2010 commercial installs are TPO.
- What should I do if my flat roof is leaking right now in Toronto?
- Contain interior damage immediately: bucket, tarp over furniture, and if water is pooling in a ceiling bubble, poke a small controlled drain hole. Then call us, we offer same-day response for active flat roof leaks. Do not go on a wet flat roof without non-slip footwear and someone below who knows you're up there. A temporary tarp is the safest DIY measure while you wait.
- Can flat roofs be emergency-repaired in winter?
- Yes. We carry cold-weather-rated patch material and torch equipment that works down to -10°C. Active leaks don't wait for spring. We stabilize the failure with a compatible cold-temperature repair, document for a permanent repair follow-up once temperatures allow full bonding, and tarp if needed for overnight protection.
- How quickly can you respond to a flat roof emergency in the GTA?
- Same-day in most cases, within 2 hours for active commercial leaks. We cover the full GTA. Toronto, Scarborough, Etobicoke, North York, Mississauga, Brampton, and surrounding areas. Call (647) 383-8664 directly for fastest dispatch.
- Why do flat roofs leak more in Toronto winters?
- Toronto's freeze-thaw pattern, regularly crossing 0°C multiple times a week from November through March, is the flat roof's primary enemy. Water enters micro-cracks in seams and membranes, freezes and expands, and turns a hairline seam failure into a gaping split. Blocked drains compound the problem: ponded water that freezes adds enormous weight and hydraulic pressure to the membrane.
- Does snow and ice damage flat roofs in Toronto?
- Yes, in two ways. Physical load from heavy wet snow stresses the deck structure. More damaging is ice formation at blocked drains, water backs up across the membrane surface, freezes in place, and the expansion-contraction cycle opens every vulnerable seam. Post-winter inspection is the single most important maintenance task for any flat roof in the GTA.
- Should flat roofs be cleared of snow in Toronto?
- For most properly designed flat roofs, no, the deck and membrane are rated for snow loads under Ontario Building Code. Exception: if drainage has already been compromised, an unusually heavy snowfall on a blocked drain could cause structural concern. Clear if you have a pre-existing drainage problem, not as standard practice.
- What is ice damming and does it affect flat roofs?
- Classic ice dams, the ridge of ice that forms at sloped eave overhangs, are primarily a pitched-roof problem. Flat roofs have their own equivalent: blocked drains that allow meltwater to pond and refreeze across the membrane surface. The result is similar, water forced through the membrane, but the solution is different: drain maintenance and membrane integrity rather than attic ventilation corrections.
- Who is responsible for flat roof repairs on a commercial property in Ontario?
- Typically the property owner or, under a commercial lease, whoever the lease assigns building envelope responsibility to, often the landlord for the base structure. Triple-net leases sometimes pass roof maintenance to the tenant. Property managers should get a written inspection report to document condition at lease transitions. We provide inspection reports for commercial properties throughout the GTA.
- How often should a commercial flat roof in Toronto be inspected?
- Twice a year: once in spring to assess winter damage and clear drains before heavy rainfall season, and once in fall before freeze-up to ensure every seam and penetration is sealed. Commercial roofs with HVAC equipment should get an additional inspection after any major equipment installation or service, as mechanical crews frequently damage membranes inadvertently.
- Can you handle flat roof repairs for multi-unit residential buildings in Toronto?
- Yes. We work on condos, apartment buildings, and multi-unit residential across the GTA. Commercial flat roof work involves additional logistics, coordinating with property managers, scheduling around tenants, and providing written reports for condo corporations. We have done this across dozens of buildings in North York, Scarborough, Etobicoke, and the downtown core.
More ways Blue Knight can help.
Ready to schedule your estimate?
We come to you, assess the roof, and give you a written quote. You are not obliged to proceed. Most estimates completed same week.