Blog
November 2, 2026
Is your flat roof starting to show signs of wear? Cracks, water pooling after rain, leaks that keep coming back despite repairs: it may be time to consider a complete roof replacement. In Terrebonne, whether the building is commercial, industrial, an apartment building or a flat-roofed home, a well-planned roof replacement saves a lot of headaches.
An flat roof replacement is a major project. Understanding when it is justified, how it unfolds and how to prepare for it helps you make an informed decision.
The question often comes up: is it better to repair the roof or replace it entirely? The answer depends on the general condition of the membrane, the condition of the insulation and the repair history. A roof replacement becomes the solution to consider when:
Patching a roof at the end of its life often just delays the inevitable while paying for temporary repairs. Conversely, replacing a roof that is still sound would be unnecessary. That is why assessing the actual condition of the roof always comes first.
The roof is first inspected in detail: condition of the membrane, moisture in the insulation, condition of the roof deck, upstands, flashings, roof drains and water drainage. This assessment defines the actual scope of the work.
In most cases, the old membrane is completely removed, along with any wet or damaged insulation. Installing a new membrane over a deteriorated system can hide problems and compromise the adhesion of the new system. The areas around the building are protected and debris is removed as the work progresses.
Once the roof is stripped, the roof deck is inspected. Sections that are rotten or warped by moisture are replaced. This work is essential: a roof is never stronger than the substrate it rests on.
Rigid insulation boards are then installed. They can also be used to create slight slopes toward the roof drains. Poor drainage is a common cause of premature deterioration of flat roofs: the roof replacement is an opportunity to correct the areas where water used to pool.
Next comes the elastomeric membrane made of SBS modified bitumen, installed in two plies: a base sheet and a granulated cap sheet that protects the system from UV rays. Depending on the substrate, the insulation and the building’s constraints, the membranes are torch-applied or self-adhered. Toitures OBM installs Soprema systems in particular, such as the conventional mechanically fastened system or the conventional self-adhered system.
The upstands along parapets and walls, the flashings, the penetrations and the connection of the membrane to the roof drains are carefully redone. These details largely determine the watertightness of the new roof.
A roof replacement requires preparation. On a commercial or industrial building, you need to think about access for customers and employees and the schedule of operations. In an apartment building, tenants must be informed of the work period and the possible noise. To find out whether a permit is required, check with the City of Terrebonne.
Timing also matters. A roof replacement planned before leaks reach the insulation and the inside of the building limits the scope of the work. The cost of the project depends on the surface area, the condition of the roof deck, the amount of insulation to be replaced, the system chosen and the number of penetrations. A detailed quote, prepared after the roof assessment, specifies what is included. Financing is offered through Financeit.
A properly installed and regularly maintained elastomeric membrane can last several decades. To get the most out of it, an inspection in the spring and another in the fall is a good benchmark: cleaning the roof drains, checking the seams, upstands and penetrations, and examining the general condition of the membrane. A small defect caught early is easy to correct.
Toitures OBM specializes in elastomeric membrane flat roofs for commercial, industrial and multi-unit buildings, as well as for residential flat roofs. Located at 1215 Tellier Street in Laval, the company carries out elastomeric roof replacement work in Terrebonne and elsewhere on the North Shore, as well as in Laval and Montreal.
Before recommending a roof replacement, the Toitures OBM team assesses the condition of the roof and the needs of the building to avoid unnecessary work, then presents clear, well-explained recommendations. The company is Soprema PAQ+S certified, CAA-Québec Recommended and holds RBQ licence 5778-2823-01.
In most cases, yes. The work takes place on the roof, but it involves noise and comings and goings. It is best to inform occupants in advance and to plan access to the job site.
A roof replacement replaces the roofing system, including any damaged membrane and insulation. Resurfacing keeps the existing membrane: it is cleaned and prepared, then a cap sheet is applied. It is only suitable for a membrane that is worn on the surface but still watertight.
Yes, it is often the opportunity to do so. When the insulation is installed, slopes can be created or corrected to direct water toward the roof drains.
A well-prepared roof replacement protects your building for many years. To have your flat roof in Terrebonne assessed, contact the Toitures OBM team at 514-449-5469, Monday to Friday from 8 a.m. to 5 p.m., or fill out the form to get a free quote.
OBM Roofing
Elastomeric membrane specialists for commercial, industrial and multi-unit buildings in Laval, Montreal and the North Shore.
