Blog
20 April 2026
For a Mascouche owner whose building has a flat roof, an elastomeric roof is a recognized solution for long-term watertightness. Made of SBS modified bitumen membranes installed in two layers, it is suitable for commercial, industrial and multi-unit buildings as well as for residential flat roofs.
This article explains what an elastomeric membraneis, how its installation works step by step and which factors influence its service life.
Elastomeric membrane is bitumen modified with a polymer, SBS (styrene-butadiene-styrene), and reinforced with a mat. The bitumen makes the membrane watertight, while the polymer gives it elasticity.
This elasticity allows the roof to follow the building’s movements caused by temperature swings and freeze-thaw cycles without cracking. The granulated surface of the cap sheet, for its part, protects the membrane from UV rays and weathering.
The two-ply system layers a base sheet and a cap sheet with staggered seams. If the surface is damaged in one spot, the base sheet continues to protect the building. This redundancy reduces the risk of water infiltration.
Whether it is a roof replacement or new construction, an elastomeric roof is installed using a structured method.
It all starts with a thorough analysis of the roof’s condition and the building’s needs: condition of the membrane, moisture in the insulation, roof drain performance, upstands and penetrations. This step makes it possible to recommend only the work that is needed.
In a roof replacement, the old layers are removed as needed and the substrate is repaired. The surface must be clean, dry and stable before installation.
Depending on the system selected, a vapour barrier is installed, followed by the insulation and a support board. These components can be mechanically fastened or adhered.
The first membrane is torch-applied or self-adhered. It forms a first continuous barrier, with carefully sealed overlaps.
The second, granulated membrane covers the base sheet with staggered seams. It protects the whole assembly against UV rays and the elements.
The upstands along the parapets, the flashings, the roof drains and the penetrations receive special attention, because these are the spots where leaks most often start.
Once the installation is complete, the team checks the overlaps, the upstands and the connection of each roof drain. It also makes sure that water flows properly toward the drainage points and that the roof is cleared of job site debris. The owner is then informed of the recommended maintenance for the new roof, including regular roof drain cleaning and a seasonal inspection.
Toitures OBM installs Soprema systems, including the mechanically fastened conventional system and the self-adhered conventional system. The first secures the components to the roof deck with fasteners, while the second relies on the adhesion of the membranes. The choice depends on the roof deck, the insulation and the job site constraints, and it is explained to the owner before the work begins.
With regular maintenance, an elastomeric roof can protect a building for several decades. Several factors make the difference.
Well-welded overlaps, properly executed upstands and careful detailing around the roof drains reduce the risk of water infiltration.
Ponding water puts stress on the membrane and eventually finds the slightest weakness. Clear roof drains and a slope that actually directs water toward them help a great deal.
Maintenance and inspection cover the roof drains and water drainage, the seams, the upstands and penetrations, and the overall condition of the membrane, including roof drain cleaning. One visit in the spring and another in the fall make it possible to correct small problems early.
A localized repair or resurfacing (cleaning, preparation of the existing membrane and a cap sheet) done at the right time can postpone a complete roof replacement. Conversely, an ignored leak can soak the insulation and expand the scope of the work required.
Toitures OBM is located at 1215 Tellier Street in Laval and installs elastomeric roofs in Mascouche and elsewhere on the North Shore, as well as in Laval and Montreal. Its services include elastomeric roof replacement, new flat roof construction, repair, resurfacing, and maintenance and inspection.
Toitures OBM is Soprema PAQ+S certified, CAA-Québec Recommended and holds RBQ licence 5778-2823-01. Financing is available through Financeit. The team can be reached Monday to Friday, from 8 a.m. to 5 p.m.
Installing membrane requires a dry substrate and favourable weather conditions. Depending on the situation, some work can be scheduled for another season. The roof assessment is an opportunity to discuss this.
Not necessarily. If the problem is localized and the rest of the membrane is sound, a targeted repair may be enough.
Yes. It is used on commercial, industrial and multi-unit buildings, as well as on residential flat roofs.
To have your flat roof assessed or to plan a roof replacement, contact Toitures OBM at 514-449-5469 or request a free quote using the form. The team will clearly explain the condition of your roof and the possible options.
OBM Roofing
Elastomeric membrane specialists for commercial, industrial and multi-unit buildings in Laval, Montreal and the North Shore.
