What replacing a roof means
Replacing a roof means starting over from a sound surface. We tear off the old covering, check the wood deck, replace damaged boards or panels, then install a new system with its flashing, vents and accessories.
A roof repair fixes a localized defect on a roof that is still in good shape. A replacement makes the whole roof new.
Two families of roofs dominate in Montreal. According to the City of Montreal, a roof with a slope under 2:12, or 16.7%, is considered flat or low-slope. That is the case for most plexes and apartment buildings. From 2:12 up, it is a pitched roof, like those on bungalows and cottages, most often covered with asphalt shingles. Materials, rules and the course of the job differ between the two.
When replacement becomes the right choice
The age of the covering is a first benchmark. According to manufacturers, and depending on the quality of installation, typical lifespans are:
- asphalt shingles: 15 to 30 years
- tar and gravel: 15 to 25 years
- elastomeric membrane: 25 to 35 years
- TPO and EPDM: 20 to 30 years
- metal: 40 years and more
Age is not the whole story. A well-ventilated, well-maintained roof often outlasts the average. A poorly installed roof can fail much sooner. Other signs weigh in the decision:
- leaks that come back in different places
- repairs that get closer and closer together
- a covering worn over the whole surface, not just in spots
- a deck that feels soft underfoot when we walk on it, or that ripples
- a planned sale, or a request from the insurer
Who it is for
Replacement mainly concerns the owner of a house or plex whose roof has reached the age of its materials. It also concerns the buyer who learns from an inspection report that the roof needs replacing soon, and the owner whose insurer asks for work. In all three cases, everything starts with an examination of the roof.
A plex flat roof and a bungalow pitched roof
On a plex with a flat roof, the covering is a membrane or an older tar and gravel system. The job is all in the details: the upstands along parapets, the drain, the vents, the joint with the next building where walls touch. Access is often from the lane or the front. That complicates material delivery and the placement of the dumpster.
On a bungalow or cottage with a pitched roof, the covering is most often asphalt shingles, sometimes metal. Attention goes elsewhere: valleys, roof edges, chimney flashing, attic ventilation. The yard around the house usually makes our work easier.
Flat roofs dominate in central neighbourhoods, where plexes stand in rows. Pitched roofs are more common in areas of bungalows and cottages. Tell us in your request which type of roof you have.
What a replacement lets you fix at the same time
An open roof is an opportunity that does not come often. Some defects are much easier to correct while the old covering is off.
- Insulation. On a flat roof, insulation can be added or replaced from above, before the membrane goes on.
- Ventilation. On a pitched roof, this is the time to add or replace vents and check that air moves well through the attic.
- Drainage slopes. On a flat roof where water pools, tapered insulation can bring the water back to the drain.
- Flashing. Around a chimney, a wall or a parapet, flashing is redone cleanly when the covering is new too.
- Skylights. An old skylight is better replaced during the job than after. Its edges are sealed with the rest of the roof.
Bring it up during the visit. An addition included in the quote can be compared from one roofer to another. An addition decided on the roof becomes an extra.
What the city looks at
The rules vary by borough, building type and the nature of the work. According to the City of Montreal, replacing the covering of a flat roof requires a permit in most boroughs. Minor repairs and maintenance generally do not.
When a flat roof is replaced, several boroughs also require a white roof, a reflective material or a green roof, to reduce heat islands. Heritage buildings and heritage areas have additional standards, which can affect the choice of material and its appearance.
Check these points with your borough before signing. Ask us also who files the permit application, you or us, and when.
From first request to finished job
The work itself is rarely the longest part of a replacement project. Most of the time goes to waiting beforehand.
- Visits. Every contractor, including us, has to see the roof before pricing it. Appointments stretch out depending on the season.
- Quotes. They do not all arrive at the same time.
- Permit. When one is needed, the delay depends on the borough and the file.
- Waiting for a slot. Once the contract is signed, the job takes its place on the calendar. In peak season, this wait is the longest.
- The work. It moves with the weather, and a rainy day pushes everything back.
A project launched without urgency leaves you the choice of roofer and timing. A project launched after a leak leaves you whatever is still available.
How to get quotes
Three quotes give a solid basis for comparison. For them to compare, every contractor, including us, has to go up on the roof or at least examine it closely, and price the same work.
Before the visits, gather the approximate age of the roof and the date of the last work if you know it, the spots where water has already come in, access to the roof and yard, and your date constraints.
Ask for a detailed written document. A one-line quote with a single amount lets you compare nothing. Materials, layers installed, what happens to the flashing and how damaged decking is handled must appear in black and white.
Common owner mistakes
- Waiting for the leak. A leaking roof is replaced in a rush, with fewer choices and less time to compare.
- Choosing on price alone. The total says nothing about what will be installed or who will install it.
- Comparing quotes that describe different work. Two prices compare only if both roofers priced the same thing.
- Forgetting the permit. The question comes before signing, not the morning the dumpster arrives.
Before you sign
Ask us for our RBQ licence number and check it with the Régie du bâtiment du Québec, as with any contractor. The register of licence holders is public on the RBQ website, and the check takes a few minutes.
Then ask for the warranties in writing: the manufacturer's on the materials and the labour warranty on the installation. Our quote states the labour warranty and its length. Finally, make sure the contract includes everything the quote promised.
Frequently asked questions
How long does it take to replace a roof?
The length of a roof replacement depends on the surface, the type of roof, access and the weather. A small, simple roof goes quickly, while a large flat roof with many details takes longer. Our quote gives you an estimated duration.
Can you replace only part of the roof?
Yes, when one section is clearly more worn than the rest, such as a very exposed slope. The joint between old and new then becomes a point to watch. Ask us whether a partial replacement seems reasonable in your case.
Do you need a permit to replace a roof in Montreal?
In most boroughs, replacing the covering of a flat roof requires a permit. For a pitched roof or a heritage building, requirements change from one area to another. Your borough will give you the exact answer for your address.
Can you stay in the house during the work?
Yes, in most cases you can stay in the house during the work. The work is done from outside, but expect noise and vibration during the day. Ask us for the crew's planned schedule.
What is the best roofing material?
No material is the best for every roof. On a pitched roof, asphalt shingles cost the least and metal lasts the longest. On a flat roof, elastomeric membrane is the most common in Montreal, and TPO or EPDM suit other situations. The right choice depends on the slope, the budget, how long you plan to keep the building and your borough's requirements.