Redoing Your Roof in Montreal: Permits, RBQ and the 5 Mistakes That Cost You

Redoing your roof is one of the biggest projects a homeowner undertakes in a lifetime. Between $8,000 and $25,000 of investment, several days of work, and 20 to 25 years of commitment to the result. Yet it’s also one of the projects where the pitfalls are most numerous: a non-certified contractor, an incomplete quote, a forgotten permit, non-compliant materials. The slightest misstep can turn an investment into a nightmare.

This article reviews the regulatory elements (permits, RBQ certification), the steps of a well-run project, and the five most frequent mistakes that Montreal roofers see in homeowners who call them in for damage control.

The essentials in 30 seconds

• A permit isn’t always required, but the roofer’s RBQ certification is mandatory for any job over $10,000.
• Serious quotes detail the underlayment, the shingle type, the ventilation and the warranty duration.
• The 5 costliest mistakes: a non-certified contractor, skimping on the underlayment, forgetting ventilation, paying the full amount in cash, a verbal warranty.
• A well-prepared job lasts 1 to 5 days and delivers 25 to 30 years of peace of mind.

Permits, RBQ and the Rules of the Game in Montreal

First thing to clarify: in the vast majority of cases, redoing your roof in Montreal does not require a municipal permit, provided you replace like-for-like (same visible materials, same roofing type, same dominant colour). As soon as you change the appearance — going from black to light grey shingles, adding a dormer, converting a sloped roof to a flat one — a permit generally becomes required, and timelines can stretch from two to six weeks depending on the borough.

More importantly: the roofer’s RBQ certification. The Régie du bâtiment du Québec requires that a contractor carrying out work over $10,000 hold a valid licence in the appropriate sub-category (roofing, waterproofing). This licence guarantees that the contractor has demonstrated their technical skills, their solvency, and that they comply with the Quebec Construction Code. Working with a non-certified roofer means exposing yourself both to technical risks and to losing any recourse with the warranty plan.

According to Les Couvreurs Duro Toit, about 1 Montreal homeowner out of 5 who used their services in 2025 to repair a new roof had initially hired a non-certified installer — a figure that says a lot about the prevalence of the phenomenon and the hidden cost of false economies.

The 5 Mistakes That Cost Homeowners the Most

From seeing the same problems recur, experienced roofers have identified five recurring mistakes that turn a good project into a bad memory. Here they are, in the order in which they do the most damage.

• Choosing the lowest bidder without verifying the RBQ licence: an immediate saving of 10 to 20% that can cost triple in repairs.
• Skimping on the underlayment (Ice & Water Shield): this invisible detail protects critical zones (eaves, valleys, flashing) and rarely costs more than $400 extra on a full project.
• Neglecting attic ventilation: without adequate ventilation, the new roof will age 30% faster and ice dams will reappear from the first winter.
• Paying the full amount upfront or in cash: a reasonable deposit (15 to 30%) and a final payment after acceptance are enough. No serious roofer demands more.
• Accepting a verbal warranty: the installation warranty must be written, dated, and state exactly what is covered and for how many years.

Each mistake, taken alone, may seem minor. Combined, they turn a $12,000 project into a total expense of $18,000 or more over five years. Simple vigilance when selecting the contractor avoids most of these pitfalls.

The Right Time and the Right Preparation in Montreal

In Montreal, the roofing season generally runs from mid-April to late November, with an ideal window between May and late September. Stable temperatures and moderate humidity allow optimal self-adhesion of shingles and perfect welding of membranes. Off-season, the work remains possible but requires extra precautions and often costs a bit more.

The best preparation begins three to six months before the work. Request three detailed quotes from RBQ-certified roofers, compare not only the prices but also the inclusions (underlayment, ventilation, shingle type, installation warranty), and systematically verify the licence number on the RBQ website. Ask to see 2 or 3 recent job sites in your neighbourhood — a serious roofer has no difficulty providing them.

On the day of the work, plan to clear the ground around the house, protect the shrubs and outdoor furniture, and inform your neighbours. A well-prepared job on a typical Montreal duplex lasts 2 to 3 days, generates a lot of noise but little lasting mess, and ends with a final inspection that you should attend to validate the quality of the work and receive all the warranty documents.

Frequently asked questions

Do you need a permit to redo your roof in Montreal?

In most boroughs, no, provided the materials and appearance are identical. Visible changes (colour, shingle type, added elements) may require a permit.

What does RBQ certification verify?

The Régie du bâtiment du Québec verifies technical qualification, financial solvency and compliance with construction standards. A roofer without an RBQ licence should never be hired.

What is the typical warranty for a new roof?

Shingles are warranted by the manufacturer for 25 to 30 years, and the installation by the roofer for 5 to 10 years. Both warranties must be documented in writing.

Take action with Les Couvreurs Duro Toit

Planning to redo your roof in Montreal or on the North Shore? Les Couvreurs Duro Toit, RBQ-certified, guide you from the first inspection to the final warranty. Request your detailed quote and compare with full transparency.