Finished Basement

A guide to prepare your building permit application to finish a basement.

If you plan to finish or renovate your basement for personal use, you will need a building permit. 

If you plan to create a separate dwelling unit, please refer to the Accessory Apartment page for permit requirements.

Project preparation

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

Contact Ontario One Call at 1-800-400-2255 before you dig to locate underground utilities and avoid damage during construction.

If you plan to add a bathroom, wet bar, or other plumbing fixture you are required to submit a water service calculation form to verify your water service is adequately sized to handle the additional load or if upgrading is required.

If you plan to add a basement bedroom, the basement requires an egress window or door. 

Additionally, the bedroom requires its own window based on the floor area of the bedroom. If adding a sixth bedroom, you will require a Building Code Part 6 ventilation design.

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. If your property is on the town's heritage registry it may 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. 

If you plan to add an egress door with walk up stairs, you will need to consult an engineer or BCIN qualified designer for construction drawings and details.

If your project includes excavation and your property backs onto green space, a river bed or wetland you will need Conservation Halton approval. 

Learn more on Conservation Halton's website. Contact Conservation Halton for approval at or 905-336-1158.

Trees on your property, your neighbour's property and on the municipal right of way may require tree protection, particularly when heavy equipment and excavation is involved. In certain instances, a permit may be required to remove private trees. Learn more about tree removal and how to find a licensed arborist.

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