How to Prepare for Interior Demolition: A Step-by-Step Guide

A poorly prepared interior demolition can quickly turn into a problem: unexpected structural damage, undetected asbestos, fines for work done without a permit.

The good news? With the right preparation, all of these risks are avoidable. Here is a practical guide to approaching your project in Montreal with confidence.

1. Check Whether You Need a Permit

In Montreal, not all demolition work requires a permit, but many situations do. As a general rule, you need a permit if the work affects structural elements (load-bearing walls, beams, foundations), changes the layout of rooms, or involves electrical or plumbing work.

Requirements vary by borough. Rosemont, Plateau-Mont-Royal, Outremont and Westmount have stricter rules than other areas, particularly for heritage buildings. It is strongly recommended to check with your borough or work with a contractor who manages permits as part of their service.

2. Identify the Risks Before You Start

Before the first swing of the hammer, three risks deserve special attention.

Hazardous Materials: Asbestos, Lead, Vermiculite

Homes built before 1990 may contain asbestos in insulation materials, floor tiles, plaster joints or textured ceilings. Only a lab test can confirm or rule out its presence.

Never assume an older building is asbestos-free. If hazardous materials are detected, certified firms must intervene before demolition work begins.

Load-Bearing Walls and Structural Elements

Demolishing a load-bearing wall without putting the necessary reinforcements in place can compromise the structure of the building. A qualified demolition contractor knows how to identify load-bearing walls and assess structural risks before starting work.

Utilities: Water, Electricity, Gas

Shutting off and securing utilities (water, electricity, natural gas) is a mandatory step before any demolition begins. This must be done by certified professionals: a licensed electrician for the electrical panel, a plumber for the plumbing. Never attempt to shut off these utilities yourself in a multi-unit building.

3. Choose the Right Demolition Contractor

Choosing your contractor is the most important decision of your project. Here are the criteria to check before signing a contract.

• 1
  Valid RBQ License

  Verifiable online at rbq.gouv.qc.ca. Without an RBQ license, a contractor is not legally authorized to carry out the work.

• 2
  CNESST Certification

  Proves that workers are insured. If a worker is injured on your property and the contractor has no CNESST certification, you could be held liable.

• 3
  Liability Insurance

  Recommended minimum coverage: $1,000,000. Kasa Demolition is covered for $5,000,000.

• 4
  Detailed Written Quote

  Every line item should be clearly listed: labour, debris removal, permits, CNESST compliance. A verbal price is not a contract.

• 5
  Verifiable References

  Ask to see similar completed projects and contact information for previous clients.

4. Prepare the Space for the Work

Once you have selected a contractor and signed a contract, here is how to prepare your space to minimize disruption.

• Remove furniture, appliances and personal items from the area being demolished
• Protect floors and surfaces in adjacent areas (plastic sheeting, heavy cardboard)
• Secure access to the living spaces you want to preserve
• Confirm the protection method with your contractor (barriers, HEPA filtration)
• Plan a clear access point for debris removal

5. What a Typical Interior Demolition Looks Like

A well-executed interior demolition follows a precise order that minimizes risk and keeps the project on schedule.

Key Questions to Ask Before You Sign

Before choosing your contractor, ask these questions directly. The answers will tell you a lot about how serious they are.

• Is your RBQ license valid and applicable to this type of work?
• Do you have a current CNESST certification?
• Do you handle the required municipal permits?
• How do you handle the potential presence of asbestos?
• Who is responsible for collecting and disposing of debris?
• Is the quoted price guaranteed, or could additional fees apply?
• What warranty do you offer on labour?