Blog
20 March 2026
An elastomeric membrane flat roof is a proven waterproofing system in Quebec. Whether you own a flat-roofed house, a plex or an apartment building in Terrebonne, it is useful to understand how this system works, why it stands up well to the Quebec climate and how to extend its lifespan.
Here are the essentials to know before planning a repair, resurfacing, a roof replacement or new construction.
An elastomeric membrane is an SBS modified bitumen membrane. SBS (styrene-butadiene-styrene) is a polymer added to bitumen to give it flexibility and elasticity, even in cold weather.
On a flat roof, the elastomeric membrane is installed as a two-ply system:
The membranes are torch-applied or self-adhered, depending on the system chosen. Toitures OBM installs Soprema systems, including conventional mechanically fastened systems and conventional self-adhered systems.
The membrane is only the visible part of the system. Underneath it, several layers work together:
When one of these components fails, the whole system suffers. That is why a serious inspection looks beyond the surface.
SBS modified bitumen stays flexible when the temperature drops. The membrane can therefore follow the building’s movements during the winter, which reduces the risk of cracking.
In the spring and fall, the temperature hovers around the freezing point. The two-ply system, with its welded seams, limits the openings where water could seep in, freeze and expand.
In summer, the cap sheet and its granules protect the base sheet from UV rays, which age exposed materials.
These signs do not all mean the roof needs to be replaced. An inspection makes it possible to determine the appropriate solution.
When the membrane is in good overall condition, a targeted repair solves the problem: a localized leak, resealing around a drain or a penetration, a crack or a section that has come loose.
If the membrane is sound but its surface is worn, resurfacing can extend its service life. It includes cleaning, preparing the existing membrane and applying a cap sheet.
When the membrane is at the end of its life or the insulation is wet, a roof replacement is often the most sensible solution. The old roof is removed as needed, then a new elastomeric system is installed. Toitures OBM assesses the condition of the roof before recommending a roof replacement, to avoid unnecessary work.
For a new building or an addition, the elastomeric flat roof is installed using a Soprema system suited to the planned roof deck and insulation.
With regular maintenance, an elastomeric membrane can protect a building for several decades. A few simple steps make a big difference:
For a plex or an apartment building, regular monitoring also reduces the risk of leaks into top-floor units and disruption for tenants.
Toitures OBM is a roofing contractor specializing in elastomeric membrane flat roofs, located at 1215 Tellier Street in Laval. The team serves Terrebonne, Laval, Montreal and the North Shore, working on residential flat roofs, apartment buildings and commercial buildings and industrial buildings.
The company is Soprema PAQ+S certified, CAA-Québec Recommended and holds RBQ licence 5778-2823-01. Its recommendations are clear and well explained. Financing is offered through Financeit.
Yes. In Quebec, an SBS modified bitumen membrane is called an elastomeric membrane. SBS gives the bitumen the elasticity that allows it to follow the building’s movements.
With torch-applied installation, the membrane is heated so it bonds to the layer below. With self-adhered installation, the membrane bonds thanks to its adhesive side, which limits work with an open flame. The choice depends on the building and the Soprema system selected.
Yes. In addition to commercial buildings and apartment buildings, elastomeric membranes are suitable for residential flat roofs. An inspection makes it possible to check the condition of the roof deck and insulation before the work.
For the repair, resurfacing or replacement of your elastomeric flat roof in Terrebonne, call Toitures OBM at 514-449-5469, Monday to Friday from 8 a.m. to 5 p.m., or request a free quote.
OBM Roofing
Elastomeric membrane specialists for commercial, industrial and multi-unit buildings in Laval, Montreal and the North Shore.
