Flat Roof Repair in Ontario: What Homeowners and Businesses Need to Know

Flat roofs are a popular choice within Ontario for residential as well as commercial and industrial buildings. Their modern look, lower cost, and easy accessibility for maintenance make them appealing. However, Ontario's unique climate—cold winters, freeze-thaw cycles, summer heat, and heavy rainfall—puts flat roofs to the test. This guide covers common causes of leaks, signs your flat roof needs repair, cost considerations, and practical steps to protect your investment.

#1 Why flat roofs fail

Freeze-thaw damage: Water seeps into small cracks or seams; when temperatures drop, the water freezes and expands, widening gaps.

UV and weathering: Prolonged sun exposure degrades membranes, leading to cracks and delamination.

Poor drainage: Flat roofs rely on proper slope and drainage. Clogged drains or insufficient perimeter drains cause standing water.

Ponding: Persistent water pooling can deteriorate membranes and invite leaks.

Material aging: Tar & Gravel B.U.R, EPDM, TPO, PVC, modified bitumen and coatings have different lifespans; urban environments can accelerate wear.

#2 Common flat roof materials used

Built-Up Roofing (BUR)

Modified Bitumen

EPDM

TPO/PVC

Polyurea/polyurethane seamless flat roof coatings

#3 Signs you need a repair or assessment

Visible cracks, blisters, or bubbling on the roof surface.

Water stains on ceilings or interior walls after rain.

Missing granules on a built-up roof or exposed patches.

Ponding water that doesn’t drain after 48 hours.

Seams, flashings, or penetrations showing signs of wear.

#4 Repair vs. Replacement: How to decide

Small leaks and localized damage often repairable with patching, sealing, or recoating.

Widespread damage, extensive ponding, or a roof nearing end of life. Replacement may be more cost-effective in the long run.

Restoration options. A resin-based coating system (e.g., polyurea/polyurethane) can restore a roof’s waterproofing without a full tear-off, reducing waste and downtime.

#5 Specific approach to flat roof repairs

Seasonal Timing: Schedule major repairs in late spring to early fall when temperatures are milder and curing times are optimal. Avoid winter repairs if possible due to freeze-thaw risks.

Permits and Codes: While most small repairs don’t require permits, major replacements or structural work may fall under municipal oversight. Always verify with a local contractor.

Insulation and energy efficiency: Ontario winters demand good insulation. Consider upgrading insulation during repairs to improve energy efficiency and curb heating costs.

Snow and Ice Planning: In winter, ensure your repair plan accounts for snow load and access challenges.

#6 What to ask your flat roof contractor

Experience with your roof type: EPDM, TPO, PVC, B.U.R, or Flat roof coatings.

Certification and warranties: What is covered (material vs. workmanship) and how long the warranty lasts.

VOC and environmental considerations: If you prefer low-VOC coatings or eco-friendly materials.

Maintenance plan: Recommended inspection frequency and preventive maintenance.

Local references: Recent projects in Ontario or nearby municipalities.

#7 Cost considerations

Factors affecting cost: Roof size, material, extent of damage, accessibility, permit requirements, and whether the project includes insulation upgrades or ventilation improvements.

Typical ranges (for planning purposes):

Residential, commercial or industrial flat roof repair (patches, repairs coatings): CAD $500–6,000+ depending on the complexity and extensive work involved

Moderate restoration with coatings: CAD $6,000–$15,000+ dependent on size of flat roof

Full replacement or extensive refurbishment: CAD $15,000– $40,000+, depending on size and materials

Note: These are rough estimates. Get multiple quotes to compare scope, materials, warranties, and timelines.

#8 Maintenance tips to extend life

Regular inspections: After heavy snow seasons and spring rains, check for damage.

Clean drainage: Keep drains, scuppers, and gutters clear of debris to prevent ponding.

Address ponding promptly: Even small pools can damage membranes over time.

Schedule professional inspections: Annual or semi-annual checks can catch issues early.

Consider protective coatings: A properly applied polyurea or polyurethane coating can extend life and provide seamless protection to your existing roofing membrane.

#9 Why choose Rubber It Roofing & Protective Coatings Inc. for your future projects

Local expertise: In-depth knowledge of Ontario’s climate, building codes, and common roof types in the area.

Integrated solutions: From inspection and minor repairs to restoration coatings and full replacements, with options like seamless polyurea coatings for durable, watertight results.

Sustainability: We offer restoration pathways that minimize waste and downtime, helping you meet environmental goals.

Transparent pricing: Clear quotes with options to tailor solutions to your budget, including energy-efficient upgrades.

If you’d like a no-obligation assessment of your flat roof and a tailored repair or restoration plan, we specialize in durable, sustainable flat roofing solutions for commercial, industrial, and residential properties in Toronto, Kitchener Waterloo, Brantford, Mississauga, Oakville and surrounding areas. Contact Rubber It Roofing & Protective Coatings Inc. to learn more and request a complimentary roof inspection.