In short
Damaged cornice? In most cases, it can be restored without completely replacing it, then repainted. Expect to pay between $10,000 and $30,000 on average for a cornice on a plex building, depending on its complexity, height, and façade accessibility.
A complete replacement typically costs between $15,000 and $40,000, depending on the architectural details.
As for a century-old mansard roof, it is often nearing the end of its lifespan. The exterior cladding must be replaced, and the decorative woodwork repaired or replaced, at an average cost ranging from $40,000 to $100,000.
Plan for 6 to 8 months of preparation before construction begins. These heritage restoration projects may qualify for government grants.
Much of the charm of Montreal's neighbourhoods, from Hochelaga to Outremont by way of Ville-Marie and the Plateau-Mont-Royal, comes from their ornate cornices and mansard roofs. They come in several types: wood, galvanized sheet metal, enamelled sheet metal, copper, slate or Canadian-style sheet metal (tôle canadienne). That is why the price varies so much from one building to the next. Cam Construction has been restoring cornices and mansard roofs in Montreal since 1991.
Repair or rebuild?
Cornice Restoration
In most cases, a cornice does not need to be completely replaced. We repair the damaged sections, then carry out thorough sealing and painting work. This restoration process delivers excellent, long-lasting results.
When certain sections are too damaged to be repaired, our carpenters and sheet metal specialists replace them, carefully replicating the original mouldings and architectural details.
Mansard Roof Restoration
For a century-old mansard roof, the situation is different. Most have reached the end of their lifespan. Restoration typically involves replacing some or all of the original roofing materials (traditional Canadian-style sheet metal or slate), as well as replacing certain wooden architectural elements and decorative moulded parapets.
Learn more about our mansard roof restoration services
How much does it cost?
Ballpark figures for a Montreal building. Every cornice and every mansard roof is different: only an on-site estimate gives the exact price.
| Work | Usual price |
|---|---|
| Repair sections of the cornice, then repaint it | $10,000 to $30,000 |
| Rebuild the cornice from scratch | $20,000 to $100,000 |
| Replace the cladding of a mansard roof (Canadian-style sheet metal or slate) and repair the woodwork | $40,000 to $100,000 |
Ranges given by Cael Camirand, General Director of Cam Construction. Complexity, height and access make the difference between the low and the high end of each range.
What drives the bill up
- Architectural details. This is the most significant factor. The more decorative elements and angles involved, the more labour-intensive the work becomes. A curved cornice, for example, can significantly impact the overall cost.
- Façade accessibility. Depending on the building's height and accessibility, the work may require scaffolding or a boom lift (hydraulic aerial platform). Each option comes with different costs.
- Public right-of-way occupancy permit. When scaffolding or a boom lift must be installed on the sidewalk or street, the City requires a temporary public right-of-way occupancy permit, which involves additional fees. Depending on the location in Montréal, these fees can significantly increase the overall project cost.
- Materials. Whether it's a cornice made of wood, sheet metal, or copper, or a mansard roof covered
Warning signs
Water is the real danger. Once it gets in, the building deteriorates much faster.
Slates coming loose
Slate tiles that slip or fall off the mansard roof let water reach what lies underneath.
Perforated flashing
Holes in the metal flashing.
Perforated joint or moulded sheet metal
Water often gets into the cornice or the mansard roof through these sheets.
Peeling paint
A deteriorating cornice is not just unsightly: it can be a sign of water infiltration.
The rules in Montreal
In a heritage area
In a heritage area, the City always gives priority to a return to the original features. It looks at the type of architecture, at what remains of the original on the building and at the neighbouring buildings: the cornice or the mansard roof is rebuilt the way it was when the building was built. Depending on the work, a borough permit may be required: we check the requirements and file the application for you. Learn more about our permit application service
Grants
This heritage work can be subsidized. The City of Montreal's support program for the restoration and renovation of heritage buildings covers, among other things, the roofing of a mansard roof (except asphalt shingles) and cornices visible from the street. For a building of architectural or historic interest designated in the urban plan, the City lists 30% of the cost of the work, up to $25,000; rates are higher in some heritage sites, such as Old Montreal. Two conditions to know:
- The work must not start before the grant is awarded.
- It must be done by a contractor who holds a licence from the Régie du bâtiment du Québec.
Amounts published by the City of Montreal, checked in November 2026. Check its page before counting on them.
Plan for 6 to 8 months of preparation
This is work you need to plan ahead, and preparation is very important. It normally takes 6 to 8 months before starting a restoration, especially a mansard roof restoration. We support our clients throughout that time, including with grant applications.
Season and length of the work
This work is done only during the warm season, from April to December. In winter, it becomes much more complicated. Depending on the complexity and the detail of the cornice or the mansard roof, the job takes from 1 week to 2 months.
Good paint applied on sound materials, or on the new materials of a rebuilt cornice or mansard roof, easily lasts 15 to 30 years. How long it lasts depends on the colour chosen and the exposure to the sun.
A project: four mansard roofs at Sherbrooke and Saint-André
In 2025, at the corner of Sherbrooke and Saint-André streets, Cam Construction restored four major mansard roofs: on Saint-André Street, at the corner of Sherbrooke and Saint-André, on Sherbrooke, and close by, on Saint-Hubert Street. All four were done at the same time. The neighbours saw the team at work in the area all summer. "We were all in the same place, and we really improved that area," says Cael Camirand.
Before you sign
- The RBQ licence. Check the contractor's licence with the Régie du bâtiment du Québec. Without one, there is no City grant. Cam Construction's: 2854-6760-18.
- Certification. Cam Construction is an APCHQ-certified contractor.
- The permit and the grants. Ask who handles them. At Cam Construction, we prepare the permit application and help you apply for grants.
- The original details. Ask how the mouldings and ornaments will be rebuilt. At Cam Construction, we reproduce them exactly.
