Blog
27 April 2026
A flat-roof house, duplex or triplex in Duvernay, in Laval, needs a roof that stays watertight despite the snow, rain and temperature swings of the Quebec climate. For a residential flat roof, the SBS modified bitumen elastomeric membrane is the solution that Toitures OBM installs and maintains.
This article is for residential owners: what elastomeric roofing is, the signs that a flat roof needs attention, what you can safely check yourself and the possible options depending on the condition of the roof.
A residential elastomeric roof is generally a two-ply system. A first membrane, the base sheet, is laid on the substrate or the insulation. A second one, the cap sheet, covers it. The cap sheet is coated with granules that protect the bitumen from the sun.
The SBS added to the bitumen keeps the membrane flexible, even in cold weather. It follows the small movements of the house through the seasons instead of cracking. The membranes are torch-applied or self-adhered, depending on the substrate and the roof configuration. Toitures OBM uses Soprema systems.
On a house or a plex, the flat roof often has a smaller surface than on a commercial building, but it has the same sensitive points.
Water must leave the roof quickly. On a home, it drains through one or a few roof drains, or through scuppers that pass through the parapet. A single roof drain clogged with leaves is enough for water to pool.
Along walls, parapets and the roof access hatch, the membrane rises vertically. These upstands and the flashings that protect them must stay well bonded so that water doesn’t get behind them. Over time, an upstand can come loose, especially on the sides most exposed to the sun, which is why it should be checked at every inspection.
Plumbing vent, range hood exhaust, dryer duct, air conditioner base: every element that passes through the roof is a spot where the seal must be carefully redone.
Many flat roof problems are first noticed inside. Have your roof inspected if you notice:
A leak isn’t always located right above the stain. Water can travel along the insulation or the roof deck before showing up on the ceiling. That’s why an inspection on the roof is better than guesswork.
Without going up on the roof, a few observations can help you keep track of your roof’s condition. After a heavy rain, see whether water is draining normally through the scuppers or downspouts. In spring, check the top-floor ceilings. If a neighbour can see your roof, water that is still visible several days after a rain is a good clue.
For your safety, leave the inspection on the roof, clearing the roof drains and any work on the membrane to a roofer. A membrane can also be damaged by a tool or a shovel used the wrong way.
Toitures OBM first assesses the condition of the roof and the needs of the house, then clearly explains what is recommended and why. The goal is to avoid unnecessary work.
With regular maintenance, a properly installed elastomeric membrane can protect a house for several decades.
Toitures OBM is a roofer specializing in elastomeric membrane flat roofing, based at 1215 rue Tellier in Laval. In addition to commercial buildings, industrial and multi-unit buildings, the company handles residential flat roofs in Duvernay and in other parts of Laval, such as Saint-François and Vimont, as well as in Montreal and on the North Shore.
Toitures OBM is Soprema PAQ+S certified, CAA-Québec Recommended and holds RBQ licence 5778-2823-01. For owners who want it, financing is available through Financeit.
Yes. The two-ply SBS modified bitumen system can be installed on a single-family house just as well as on a duplex, a triplex or an apartment building.
Not necessarily. A stain can come from a localized problem, such as a poorly sealed vent or a loose upstand. The inspection shows whether a repair is enough or whether the membrane is worn over a larger area.
One inspection in spring and another in fall make it possible to catch problems early, before and after the cold season.
To have the elastomeric roof on your home inspected or repaired, 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.
OBM Roofing
Elastomeric membrane specialists for commercial, industrial and multi-unit buildings in Laval, Montreal and the North Shore.
