Interior Alteration

A guide to prepare your building permit application for interior alterations.

Interior alterations are any change occurring inside the house that isn't decorative. This could include wall removals, adding new windows or enlarging existing ones, adding new or relocating plumbing fixtures. 

Permits typically are not required for replacing existing cabinetry, sinks, faucets, toilets and cosmetic changes to surfaces. 

Project preparation

Detailed information is needed to properly evaluate your plans and the unique conditions of your property: 

If you are removing a load bearing wall, you may require engineered beams. If you are not sure if a wall is load bearing contact a BCIN qualified designer, architect or engineer. If you are adding or removing walls, indicate on the drawings how the HVAC will be modified to ensure the mechanical system's integrity is maintained.

Windows and exterior doors

If you are making changes to the building façade for windows or doors you will need heritage approval.

Heritage properties are managed to conserve important cultural heritage attributes. Properties on the town's heritage registry require heritage approval. Learn more on our Heritage Planning page or contact a town Heritage Planner for assistance at 905-845-6601 ext. 3870 or 3875. 

Other considerations

New construction or physical changes to your building or land may result in additional property taxes being levied.  These changes may result in an increase of value to your property, and the town is legislated to issue additional property tax billings due to an increase in value. 

  • The Municipal Property Assessment Corporation (MPAC) can provide the Town with increased property values (supplementary and/or omitted assessment) for the current tax year and two years prior when: 
    • land is omitted from the assessment roll 
    • use of the property changes 
    • property is improved due to construction, an addition, or renovation 
  • You will receive a Property Assessment Change Notice from MPAC, informing you of the supplementary and/or omitted assessment value. 
  • Supplementary and/or omitted residential property tax bills are calculated by multiplying the supplementary and/or omitted assessment value by the tax rate for the applicable tax year. 
  • MPAC has authority to assign omitted and/or supplementary assessment for the current year and two years prior. 
  • If you own a new property or have purchased a home in a new subdivision, the first regular bill you receive from the Town may only be for the portion relating to land value. You should expect a supplementary and/or omitted bill for the structure to follow. 
  • Supplementary and/or omitted assessments are issued under the authority of Section 34 and 33 of the Assessment Act. 

For more information on supplementary and omitted taxes, visit our Property Assessments & Appeals page or email