Construction 3 Lacs inc.
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Service · Vaudreuil-Soulanges and the West Island

Home additions in Vaudreuil-Dorion and Saint-Lazare

When moving costs more than building on. A rear extension or a second storey, blended into the existing house, with one contractor from the dig to the paint.

Estimate onlineBook a free visit
Or call: 514-444-2391

What is included

Everything below is in the written quote, line by line. Nothing is a surprise on the invoice.

  • Support for the drawings and municipal permit
  • Excavation and concrete foundation with our partner
  • Framing, roofing and a watertight tie-in to the existing house
  • Windows, doors, insulation and matching cladding
  • Plumbing, electrical and heating extended into the addition
  • Complete interior finish: drywall, flooring, paint

From our job sites

Real projects, photographed by our crew in Vaudreuil-Soulanges and the West Island.

See all our work

How it goes

From the first call to the handover

  1. Visit and feasibility

    We check setbacks, allowed lot coverage and the state of the current foundation before dreaming too big.

  2. Drawings and permit

    Drawings by a technologist or architect, structural calculations if needed, application filed with the town.

  3. Construction

    Excavation, foundation, framing, roof, envelope, then the interior. The opening into the existing house comes last to keep dust down.

  4. Final walkthrough

    Full walkthrough with you, paperwork for the town and your insurer handed over.

Building on in Vaudreuil-Soulanges

In Saint-Lazare and Les Cèdres the lots are large: a rear extension or an attached garage almost always clears the setbacks. In L’Île-Perrot and Pincourt, bungalows, split-levels and two-storeys sit on tighter suburban lots, where a second storey is sometimes the better option, provided the foundation can carry it.

In Saint-Lazare, a good share of homes are on wells and septic systems: before digging, we locate the tank and the leaching field. In Hudson, heritage sectors fall under a PIIA review, which adds a few weeks to the permit. In Rigaud, we often extend a cottage into a year-round house.

Permits, RBQ licence and warranty

An addition is the project where these checks matter most.

  • Permits in Vaudreuil-Dorion and Saint-Lazare

    Always required, with drawings. Plan for 4 to 8 weeks in most towns in the area once the drawings are filed, longer under a PIIA. We prepare the file with a technologist or architect and submit it to the City of Vaudreuil-Dorion, the Town of Saint-Lazare or your municipality. How long the permit takes is up to the town, not us; we file a complete application so it is not held up.

  • Schedule

    Plan for 2 to 4 months of work. Foundations are poured from April to November, and the opening into the existing house comes last to keep dust down.

  • RBQ licence and insurance

    Construction 3 Lacs inc. has held general contractor licence RBQ 5788-4918-01 since 2020, bonded through the APCHQ, with liability insurance and CNESST coverage. Excavation and foundation are done with our partner, under our responsibility.

  • Warranty and paperwork

    At handover you get the manufacturer warranties (windows, doors, cladding), our subcontractors’ invoices and the documents to give the town and your insurer.

What it costs

A 300 sq ft addition on a foundation lands in these ranges depending on the tier, taxes included, drawings and permit extra.

Standard

Quality materials, common finishes

$96,165to$138,384

300 sq ft, taxes included

Premium

High-end finishes, quartz, glass

$125,015to$179,899

300 sq ft, taxes included

Luxury

Custom work, premium materials

$163,481to$235,253

300 sq ft, taxes included

References based on Québec market prices (about $340/sq ft in the standard tier). The firm price is confirmed in writing after a free visit.

Try the online estimator

Questions homeowners ask

Before starting a home addition project with us.

Rear extension or second storey?

The extension costs less per square foot and you stay in the house during the work. A second storey makes sense on a small lot, but the foundation must be verified to carry it.

How long for the permit?

Plan for 4 to 8 weeks in most towns in the area once the drawings are filed, longer if the sector is under a PIIA architectural review.

Will the cladding match?

We source the same product when it still exists. Otherwise we propose a deliberate contrast, often wood or steel cladding on the new part.

Do you build additions in Saint-Lazare?

Yes. Saint-Lazare’s large lots often have room for an extension or a garage. We check setbacks and the septic system’s location at the visit, then prepare the permit application for the Town of Saint-Lazare.

How much does a home addition cost?

For a 300 sq ft addition on a foundation, plan for $96,165 to $138,384 in the standard range, taxes included, drawings and permit extra. The firm price is confirmed in writing after a free visit.

Where we do this work

Based in Vaudreuil-Dorion. Each town has its own page with the local rules and the type of houses we see there.

Your town is not listed? We also work across the West Island (Pointe-Claire, Kirkland, Dollard-des-Ormeaux, Pierrefonds, Beaconsfield, Sainte-Anne-de-Bellevue), in Châteauguay, Vaudreuil-sur-le-Lac and everywhere in Vaudreuil-Soulanges. The visit is still free.

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Tell us about your project

Call, write or send the form to discuss your project.

  1. 1. We call you backTo understand the project and set the visit.
  2. 2. Free visitWe measure and check site conditions.
  3. 3. Written quoteDetailed, line by line, no obligation.
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