Elastomeric membrane roofing is the most widely used flat roof system for residential and commercial buildings in Quebec — and for good reason. Designed specifically to handle extreme cold, freeze-thaw cycles, and heavy snow loads, SBS modified bitumen membrane outperforms traditional tar-and-gravel systems in lifespan, weight, repairability, and energy efficiency. If you own a home or building with a flat roof in Gatineau, Hull, Aylmer, or Ottawa, this guide covers everything you need to make an informed decision about your next flat roof project — from what the system actually is, to what it costs, to how long it lasts, to how to spot a problem before it becomes a major repair.
What Is an Elastomeric Membrane Roof?
An elastomeric membrane is a roofing system made from SBS (Styrene-Butadiene-Styrene) modified bitumen reinforced with either polyester or fiberglass mat. The word ‘elastomeric’ refers to its rubber-like elasticity — unlike traditional tar-and-gravel roofing, which becomes brittle in cold temperatures, an elastomeric membrane expands and contracts with temperature changes without cracking or splitting. This makes it exceptionally well-suited to Quebec’s climate, where a single day in January or February can involve a 20-degree temperature swing.
The system typically consists of two layers: a base sheet and a cap sheet, both torch-welded together by a certified technician using an open-flame propane torch. The torch application creates a fully bonded, seamless waterproof surface across the entire roof deck. Some systems use a cold-applied adhesive method instead of torch welding, but torch application remains the most common and reliable method for Quebec’s climate. Because torch welding involves open flame, it requires certified technicians with specific qualifications and insurance coverage under Quebec regulations — a fact that immediately disqualifies any unlicensed operator.
How Long Does an Elastomeric Membrane Roof Last?
A properly installed elastomeric membrane roof in Quebec lasts 35 to 40 years — significantly longer than traditional built-up tar-and-gravel roofing, which typically lasts 15 to 20 years. The actual lifespan depends on several factors: installation quality matters most, as torch-welded seams must be fully adhered with no air pockets or unbonded sections. Roof drainage is equally critical, since standing water that does not drain within 48 hours after rain accelerates membrane degradation and can cause premature failure. Every penetration — vents, skylights, chimneys, HVAC equipment — is a potential leak point if not properly flashed and sealed. Periodic inspection every three to five years significantly extends lifespan by catching minor issues before they become major problems.
It is worth noting that lifespan claims are contingent on quality installation. A poorly installed membrane — with incomplete torch adhesion, improperly lapped seams, or inadequate flashing at penetrations — can develop leaks within five years regardless of the material’s theoretical durability. This is why choosing a certified, experienced contractor matters as much as choosing the right material.
Elastomeric Membrane vs. Other Flat Roof Systems
vs. Tar and Gravel (Built-Up Roofing)
Tar and gravel has been the standard Quebec flat roof system for decades and remains common on older buildings. It is made from alternating layers of bitumen and reinforcing felt, topped with a layer of gravel that provides UV protection and ballast. While durable, the system has significant drawbacks: it is heavy — the gravel layer alone adds roughly 10 pounds per square foot of structural load — it is difficult to inspect and repair because leaks are hard to trace under the gravel, and it has a shorter lifespan than elastomeric membrane. Elastomeric membrane weighs approximately half as much and can often be installed directly over an existing bitumen surface, which reduces both project cost and waste.
vs. TPO Membrane
TPO (Thermoplastic Polyolefin) is a single-ply membrane that has grown in popularity for commercial applications over the past two decades. It is heat-welded rather than torch-applied, and it is highly reflective, which provides energy savings in hot climates. For Quebec’s cold climate, however, SBS elastomeric membrane has a significantly longer track record of performance through freeze-thaw cycling, and it is generally the preferred choice for residential flat roofs in the Outaouais. TPO seams that are not perfectly welded can open up in extreme cold, and the material does not have the same self-healing properties as SBS modified bitumen. Cossette installs both systems and will recommend the appropriate choice based on the building’s use, budget, and performance requirements.
vs. EPDM (Rubber Roofing)
EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber membrane common in the United States and parts of Canada. It is glued or mechanically fastened rather than welded, and while it handles temperature extremes reasonably well, it is susceptible to puncture and its adhesive seams can fail over time in cold climates. Elastomeric SBS membrane remains the dominant and most proven choice for residential flat roofs in the Quebec market.
What Does Elastomeric Membrane Installation Cost in Gatineau?
Flat roof installation costs in Gatineau and Ottawa vary more than shingle costs because the variables are greater. The primary cost drivers are roof area, roof complexity (the number of penetrations such as vents, skylights, drains, and HVAC curbs), ease of access, and whether the existing roof surface requires full removal or can serve as a base for an overlay installation. Insulation requirements also affect cost — some flat roofs require new insulation board before the membrane can be applied.
As a general guide, elastomeric membrane systems sit in the mid-range of flat roof options — more expensive per square foot than a basic single-ply installation, but significantly more cost-effective over the full service life than a tar-and-gravel system that needs replacement in 15 years. The cost of doing it right the first time, with a proper drainage assessment and certified torch application, almost always costs less than the combined expense of premature repairs and early replacement.
Cossette Roofing provides free on-site estimates that account for all project variables. Call 819-777-7177 to arrange an evaluation.
Can Elastomeric Membrane Be Installed Over an Existing Flat Roof?
In many cases, yes. If the existing roof surface is bitumen-based and in reasonable structural condition — no significant water-damaged insulation, no widespread delamination, no soft spots in the deck — a new elastomeric membrane layer can be installed directly over it. This overlay approach reduces labour costs and project waste and is a legitimate, code-compliant method when conditions allow. However, overlaying a roof that has underlying water damage or structural problems simply traps the existing damage and accelerates future failure. Cossette’s certified technicians perform a thorough inspection before recommending the appropriate approach, and will always advise full removal when the existing surface does not meet the criteria for a safe overlay.
For full details on Cossette’s flat roof and elastomeric membrane services, visit the flat roofing and elastomeric membrane page.
The Installation Process Step by Step
A professional elastomeric membrane installation by Cossette begins with a free on-site evaluation and measurement of the roof area. The existing surface condition and drainage are assessed, and the appropriate installation method is determined. If a full tear-off is required, the existing roofing layers are removed and the deck is inspected for damage. Any damaged deck boards are replaced before any new material is applied. Insulation board is installed if required, followed by the base sheet, which is torch-welded to the deck or adhered with cold process adhesive. The cap sheet membrane is then torch-welded over the base sheet, with all seams lapped and fully bonded. Flashings are installed around every penetration, edge, and drain, with particular attention to transition details that are common leak points. The project closes with a final inspection and full warranty documentation.
Most residential flat roofs are completed in one to three days, depending on size and the complexity of penetrations. All torch-welding is performed by certified technicians holding the required qualifications and insurance under Quebec regulations.
Signs Your Flat Roof Needs Repair or Replacement
Elastomeric membrane roofs are low-maintenance but benefit from periodic inspection. Key warning signs that a repair or replacement may be needed include visible blistering or bubbling in the membrane surface, which typically indicates trapped moisture or adhesion failure. Cracking or splitting of the membrane around flashings, penetrations, or seams is a sign of age-related brittleness or improper installation. Pooling water that does not fully drain within 48 hours after rain is a drainage problem that accelerates deterioration and should be addressed immediately. Interior water stains on ceilings below the flat roof are the most obvious indication that the membrane has been breached.
Cossette handles both new installations and full repairs of existing systems — emergency flat roof repair is available 24/7.
Neighbourhoods and Areas Served
Cossette Roofing installs and repairs elastomeric membrane flat roofs throughout Gatineau, Hull, Aylmer, Buckingham, Masson-Angers, Ottawa, Kanata, Orléans, Barrhaven, Gloucester, Embrun, Clarence-Rockland, and Cornwall. Whether your flat roof is on a 1960s bungalow in Hull, a multi-unit residential building in downtown Gatineau, or a commercial property in the Kanata technology park, the team has the equipment and certifications to handle the project.
Frequently Asked Questions
What is the difference between elastomeric membrane and TPO for flat roofs?
Elastomeric membrane (SBS modified bitumen) is torch-applied and has a proven 35 to 40 year track record in Quebec’s climate. TPO is heat-welded and more reflective, making it better suited to hot climates. For residential flat roofs in Gatineau and Ottawa, elastomeric membrane is generally the recommended choice due to its superior freeze-thaw resistance and self-healing properties.
How often does an elastomeric membrane roof need to be replaced?
A properly installed SBS membrane roof lasts 35 to 40 years in Quebec’s climate. Replacement becomes necessary when the membrane shows widespread cracking or delamination, when drainage issues have caused extensive substrate damage, or when the cumulative cost of repairs exceeds the value of continued patching. Periodic inspection every three to five years helps identify minor issues before they reach that point.
Can I install elastomeric membrane myself?
No. Torch-welded elastomeric membrane installation requires certified technicians under Quebec law. The process involves open-flame torch application, which carries fire risk if performed incorrectly, and improper installation permanently voids manufacturer warranties. Always hire a licensed RBQ contractor with specific experience in flat roof membrane systems.
What colours are available for elastomeric membrane roofing?
Elastomeric membranes are available in dark grey, black, and lighter reflective granule surfaces. Lighter-coloured cap sheets reflect summer solar heat and can meaningfully reduce cooling loads in buildings with large flat roof areas — worth considering for commercial properties or homes with habitable space directly below the flat roof.
Does Cossette Roofing provide a warranty on elastomeric membrane installation?
Yes. Cossette provides a manufacturer material warranty on the elastomeric membrane product and a separate workmanship warranty covering the installation. Both are provided in writing as part of the project documentation. Warranty terms are reviewed and explained during the estimate process.
Cossette Roofing — RBQ Licence 5697-7788-01 — 819-777-7177 — toiturescossette.ca