
Basement Renovation Montreal
Montreal's Trusted Basement Finishing Contractor
Castelli & Carson Construction transforms unfinished Montreal basements into high-performance, code-compliant living spaces. From full basement finishing to bathroom additions and legal secondary suites — every project delivered under RBQ licensing with full permit management and CCQ-compliant trades.
Why Finish Your Basement?
An unfinished basement is one of the highest-ROI renovation opportunities available to Montreal homeowners. Converting below-grade square footage into livable, functional space adds immediate resale value, increases usable square footage without expanding your footprint, and significantly improves energy efficiency through proper insulation and air sealing.
Quebec's climate demands that basement renovations be done correctly — proper vapour barrier installation, code-compliant insulation assemblies, and moisture management are non-negotiable in our environment. Castelli & Carson Construction brings the technical expertise and RBQ licensing to ensure your basement is built to last.

Basement Spaces We Build
Every basement project is designed around how you intend to use the space — built to code, built to last.
Family Room & Entertainment Space
Open-concept recreational areas designed for daily family living — proper ceiling height, acoustic insulation, recessed lighting, and durable flooring built to handle real use.
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Home Office & Professional Studio
Dedicated below-grade workspaces with dedicated electrical circuits, structured cabling, sound control assemblies, and proper ventilation — built to professional standards.
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Home Gym & Fitness Room
Functional workout spaces with reinforced flooring systems, ventilation upgrades, mirrored wall assemblies, and proper lighting — designed around how the space will actually be used.
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Basement Bathroom Addition
Full and half-bath additions including concrete break-out, licensed plumbing rough-in, waterproof membrane installation, tile work, and fixture installation — coordinated under one contract.
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Secondary Suite & In-Law Unit
Legal secondary dwelling configurations built to Montreal and Quebec Construction Code standards — egress compliance, fire separation, independent mechanical systems, and permit management included.
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Laundry, Storage & Utility Areas
Organized utility zones, laundry rooms, and built-in storage solutions integrated into the overall basement layout — functional spaces that make the rest of the project work better.
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Basement Project Gallery



Basement Renovation Services Available In
Montreal
- ✓ Ahuntsic-Cartierville
- ✓ Anjou
- ✓ Côte-des-Neiges–NDG
- ✓ LaSalle
- ✓ Lachine
- ✓ Le Sud-Ouest
- ✓ Mercier–Hochelaga-Maisonneuve
- ✓ Outremont
- ✓ Pierrefonds-Roxboro
- ✓ Plateau-Mont-Royal
- ✓ Rosemont–La Petite-Patrie
- ✓ Saint-Laurent
- ✓ Saint-Léonard
- ✓ Verdun
- ✓ Ville-Marie
- ✓ Villeray–Saint-Michel–Parc-Extension
West Island
- ✓ Pointe-Claire
- ✓ Dorval
- ✓ Beaconsfield
- ✓ Kirkland
- ✓ Dollard-des-Ormeaux
- ✓ Sainte-Anne-de-Bellevue
- ✓ Baie-D'Urfé
- ✓ Senneville
Laval
- ✓ Chomedey
- ✓ Sainte-Dorothée
- ✓ Laval-des-Rapides
- ✓ Duvernay
- ✓ Auteuil
- ✓ Sainte-Rose
- ✓ Fabreville
South Shore
- ✓ Longueuil
- ✓ Brossard
- ✓ Saint-Lambert
- ✓ Boucherville
- ✓ La Prairie
- ✓ Candiac
- ✓ Châteauguay
- ✓ Saint-Constant
- ✓ Delson
Vaudreuil Region
- ✓ Vaudreuil-Dorion
- ✓ Saint-Lazare
- ✓ Hudson
- ✓ Rigaud
- ✓ Pincourt
- ✓ Notre-Dame-de-l'Île-Perrot
- ✓ L'Île-Perrot
- ✓ Terrasse-Vaudreuil
Basement Renovation FAQ
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RBQ Licensed & CCQ Compliant. We respond within 24 hours.
