Flat Roofing in Toronto
& the GTA
TPO, EPDM, and modified-bitumen systems for additions, whole-house flat roofs, and small commercial — installed watertight and backed by 20–25 year membrane warranties. Leaking right now? We respond to flat-roof leak calls within 24 hours.
response
The roof where drainage matters more than the material
A flat roof has a low slope — about ¼ inch per foot — engineered to drain rather than pond. In the GTA the common systems are TPO, EPDM, and modified bitumen, lasting 20–30 years when installed right. The membrane choice matters, but the thing that actually decides how long a flat roof lasts is drainage and workmanship at the seams — which is exactly where we focus.
Ponding water is the #1 cause of early flat-roof failure in the GTA. We build minimum ¼"-per-foot slope and verify drain capacity on every install — the unglamorous part that adds a decade.
On a flat roof the leak is rarely above the stain — water travels the deck. We trace the true source at seams and penetrations, and respond to active leaks within 24 hours.
Most flat-roof problems are a targeted repair, not a re-roof. We apply the >50%-of-replacement-cost rule honestly and tell you when a patch is the smarter spend.
Leak or problem? Diagnose it first.
Before anyone quotes you a new roof, find out what's actually wrong. Pick the symptom and we'll tell you the likely cause, the urgency, and — honestly — whether it's a repair or a replacement. Most of the time it's a repair.
Tell us the symptom
Most flat-roof problems are a targeted repair, not a full replacement — and we'll tell you which. Pick what you're seeing for the likely cause, the urgency, a real price band, and an honest repair-or-replace verdict.
TPO, EPDM, or modified bitumen?
Three solid systems, each best at something different. Answer three quick questions and we'll point you to the right membrane for your building and how you'll use it.
Answer the three questions
We'll point you to the membrane that fits your roof, budget, and how you'll use it. Honestly, though — on a flat roof, who installs it matters more than which product. A great EPDM install beats a sloppy TPO one every time.
How a Buildoreno flat roof goes on
Flat roofing demands precision. Here's how we ensure a watertight result every time.
- 1Roof Assessment & Survey
We thoroughly inspect your existing flat roof, identify problem areas, assess drainage, and document current conditions.
- 2System Recommendation & Quote
Based on your building type, budget, and longevity goals, we recommend the best flat roofing system and provide a detailed quote.
- 3Scheduling & Permits
We coordinate timing to minimize business disruption, pull necessary permits, and schedule material delivery.
- 4Surface Preparation
We remove or prepare existing roofing, repair substrate damage, ensure proper drainage slopes, and install insulation as needed.
- 5Membrane Installation
Our crews install your chosen roofing system with meticulous attention to seams, penetrations, and edge details—where most flat roof failures occur.
- 6Quality Check & Warranty
We conduct flood testing or visual inspection, document the installation, and provide manufacturer and workmanship warranties.
How much does flat roofing cost?
Most GTA flat roofing runs $8–$15 per square foot installed, with residential projects landing in the $8,000 – $25,000+ range. The biggest variables are membrane system, insulation depth, and the number of penetrations. Emergency leak repairs are priced separately — every estimate is itemized.
| Project type | Typical size | Price range | What's included |
|---|---|---|---|
| Small residential flat roof | 400–800 sq ft | $6,000 – $12,000 | TPO or EPDM, rear addition or garage |
| Mid-size residential | 800–1,500 sq ft | $10,000 – $22,000 | Includes insulation, drip edge, flashing |
| Large residential / row home | 1,500–2,500 sq ft | $18,000 – $35,000 | Multi-day install, parapet + coping work |
| Small commercial | 2,000–5,000 sq ft | $20,000 – $50,000 | TPO with manufacturer warranty |
| Mid-size commercial | 5,000–15,000 sq ft | $50,000 – $150,000 | Higher-spec system, after-hours options |
| Emergency leak repair | Per repair | $400 – $1,500 | 24-hour response across the GTA |
| Skylight integration | Per skylight | $1,200 – $3,500 | Includes flashing + waterproofing |
| Annual maintenance program | Per visit | $300 – $800 | Bi-annual inspection, drain clearing |
Pricing reflects typical GTA 2026 flat roofing rates. Commercial pricing varies based on warranty tier and after-hours scheduling. Emergency repair pricing assumes daytime weekday response; after-hours and weekend response has a premium. Every Buildoreno flat roof estimate is itemized — membrane, insulation, flashing, disposal, and any permit fees called out separately.
What else to coordinate
A flat roof rarely stands alone. These are the pieces worth doing in the same project — one mobilization, and every transition stays watertight.
Most GTA homes pair flat-roof additions with a sloped main roof. We handle both under one project so the transition flashing between them is detailed and watertight — not a future leak.
Metal roofingAdding or replacing skylights during a flat-roof install integrates the flashing with the membrane from the start — far cleaner and cheaper than cutting one in later.
Skylight installationGazebos, pergolas, and rooftop terraces use the same TPO/EPDM/mod-bit systems. If you're building outdoor living, we can waterproof it with the same crew and warranty.
LandscapingSee the difference
Drag across a real GTA flat-roof replacement — the same building, before and after.
Recent flat roofs
TPO, EPDM and modified-bitumen membrane projects across the GTA.
Flat roofing questions, answered
For most commercial applications in the GTA, we recommend TPO (thermoplastic polyolefin) or EPDM rubber roofing. TPO offers excellent energy efficiency with its reflective surface, while EPDM provides proven durability at a lower cost. The best choice depends on your building size, budget, and energy goals.
A properly installed flat roof typically lasts 20–30 years. TPO and EPDM membranes come with 20-25 year manufacturer warranties. Modified bitumen systems can last 25-30 years. Lifespan depends heavily on installation quality, drainage, and maintenance.
Yes, we offer flat roof repair services including emergency leak repairs. We'll identify the source of the leak—often at seams, penetrations, or flashing details—and provide either a targeted repair or recommend replacement if the roof has reached end-of-life.
Flat roofs require proper drainage design to prevent ponding water. We ensure adequate slope (minimum 1/4" per foot) and install drains, scuppers, or gutters as needed. Ponding water is the #1 cause of flat roof failure—we engineer it out from the start.
Flat roofing typically costs $8–15 per square foot installed, depending on the system chosen. This is often less expensive than sloped roofing materials on a per-square-foot basis. For commercial buildings, the larger roof area means material choice significantly impacts total cost.
Yes, we offer preventative maintenance programs for commercial flat roofs. Regular inspections catch small issues before they become expensive repairs. Most programs include bi-annual inspections, drain clearing, and minor repairs.
Gravel on a flat roof is a ballast layer over an older built-up roofing (BUR) system — it weighs the membrane down against wind uplift, blocks UV, and adds fire resistance. Modern TPO and EPDM membrane systems mechanically attach or fully adhere to the deck, so gravel isn't needed. If your existing flat roof is gravel-ballasted and failing, replacing it with a modern membrane system is usually faster, lighter, and easier to maintain.
Both. Residential flat roofs — rear additions, garages, modern infill builds, mid-century homes — are a significant part of our work. We install TPO, EPDM, and modified bitumen on residential roofs from 400 sq ft up to large row-home roofs. Pricing scales linearly with area and access; small residential roofs typically start at $6,000.
TPO and modified bitumen installations require above-freezing temperatures for proper adhesion and seam welding, so we typically schedule new installations April through November in the GTA. EPDM can be installed slightly later into the season. Emergency leak repairs continue year-round — we'll tarp and contain damage in winter and complete permanent repairs once temperatures cooperate.
We respond to flat roof leak calls within 24 hours during business days across the GTA. For active leaks during storms or off-hours, we can usually dispatch faster for temporary containment (tarping and water diversion) and schedule the permanent repair within a few days. Emergency leak response runs $400–$1,500 per repair depending on the cause and access.
Yes, but differently than pitched roofs. Modern flat roof assemblies are typically designed as 'warm roof' or 'compact roof' systems where insulation sits directly above the deck without traditional ventilation; this avoids condensation issues common in vented flat roof designs from the 1980s and earlier. We follow current Ontario Building Code requirements for the specific assembly being installed and can advise on which approach suits your project.
Yes. Flat-roof skylight integration is a common addition during membrane replacement — TPO and EPDM both handle skylight curb flashing cleanly, and installing skylights at the same time as the new membrane is faster and cheaper than retrofitting later. Pricing typically runs $1,200–$3,500 per skylight including flashing.
Membrane manufacturers warranty TPO and EPDM systems for 20–25 years (some commercial systems up to 30). Buildoreno backs the installation itself with a 5–10 year written labour warranty covering installation defects. The combined warranty package is provided at project close and is transferable on home sale — important for resale value.
Leaking, or
planning ahead?
Book a free flat-roof assessment — or call now if it's an active leak. We'll find the real source, tell you honestly whether it's a repair or a replacement, and itemize every cost.
Call (647) 254-0877