Blog
13 April 2026
Do you own an apartment building, a plex or a commercial building in Chomedey, Laval? If your building has a flat roof, the quality of the membrane and its installation largely determines how long it will stay protected from water infiltration.
A successful elastomeric flat roof, made of SBS modified bitumen membranes installed in two layers, is designed for this type of roof. This article describes the layers that make up the system, the two ways of installing the membrane and the workmanship details that matter most.
A flat roof is more than just a membrane. It is an assembly of several layers that work together. In a conventional system, you generally find, from bottom to top:
If one of these layers is poorly chosen or poorly installed, the entire system suffers. Wet insulation, for example, loses part of its effectiveness and can eventually damage the membrane above it.
The choice of method depends on the building, the substrate and the constraints of the job site. Toitures OBM works with Soprema systems, including the mechanically fastened conventional system and the self-adhered conventional system.
The membrane is heated with a torch, which melts the bitumen on its underside. As it cools, the bitumen bonds the membrane to the layer below and the rolls to one another. This method requires experience: too little heat compromises adhesion, too much heat damages the membrane.
Some membranes come with an adhesive protected by a release film. The film is removed and the membrane is pressed into place. This method reduces the use of an open flame, which can be useful near combustible materials or on certain substrates. On many job sites, the two methods are combined: a self-adhered base sheet and a torch-applied cap sheet, for example.
Most leaks on a flat roof do not come from the middle of the membrane, but from the spots where it changes direction or is interrupted. That is where the quality of workmanship shows.
A flat roof has a slight slope that directs water toward the roof drains. If water ponds in the same spot after rain, the membrane ages faster there. During installation, the membrane is carefully connected to the roof drain so that water cannot seep in around it.
The location and condition of the roof drains are also checked. A roof drain partially clogged with leaves or debris slows drainage and creates areas of ponding water, especially in the spring, when snow melts quickly.
Along walls and parapets, the membrane turns up vertically. These upstands must be properly adhered or torched and protected at the top, otherwise water can get behind the membrane.
Plumbing vents, ventilation ducts, mechanical equipment bases: every element that passes through the roof is a point that must be sealed. Both apartment buildings and commercial buildings often have several of them, which is why methodical work matters.
Even a well-installed roof eventually ages. A few signs indicate that it is time to have it inspected:
Depending on what the inspection reveals, Toitures OBM may recommend a targeted repair, resurfacing of the existing membrane or a complete roof replacement. The analysis of the roof’s condition comes before any recommendation, to avoid unnecessary work.
Toitures OBM is located at 1215 Tellier Street in Laval and specializes in elastomeric membrane flat roofs. The company works in Chomedey as well as in the other areas of Laval, such as Sainte-Rose and Vimont, and also in Montreal and on the North Shore.
Toitures OBM is Soprema PAQ+S certified, CAA-Québec Recommended and holds RBQ licence 5778-2823-01. Its services include elastomeric roof replacement, new flat roof construction, repair, resurfacing, and maintenance and inspection. Financing is available through Financeit.
It depends on the existing substrate, the presence of combustible materials and the layout of the roof. An on-site assessment makes it possible to choose between a torch-applied installation, a self-adhered installation or a combination of the two.
The insulation reduces heat loss and provides support for the membrane. If it is wet or crushed, it loses its effectiveness and can cause defects in the membrane. Its condition is therefore checked during the work.
In most cases, yes. Roofing work is done from the outside. The schedule and access are planned in advance with the owner, who can then notify the tenants.
To have your elastomeric flat roof assessed, contact the Toitures OBM team Monday to Friday, from 8 a.m. to 5 p.m., at 514-449-5469, or request a free quote using the form.
OBM Roofing
Elastomeric membrane specialists for commercial, industrial and multi-unit buildings in Laval, Montreal and the North Shore.
