Part 3 Residential Addition and Alteration

A guide to preparing your part 3 residential addition and alteration building permit application.

A part 3 residential building consists of more than three storeys or is greater than 600 m2. 

Before preparing your permit

Some approvals and permits must be in place before you start preparing your building permit application.

Additional permits and documentation may be required before preparing your building permit application, including:

  • Site plan approval: You must submit an application for site plan approval before applying for a building permit. 

  • Demolition permit: If there is an existing building on your site, you will require a separate demolition permit. A demolition permit is a type of building permit.

  • Site servicing permit: If you are proposing modifications to the site servicing or installing new services, a separate site servicing permit is required. Contact or 905-845-6601 ext 7377

  • Halton Region services permit: If adding new connections at the street, a Halton Region services permit is required. Learn more at Halton Region permits.

Project preparation

Detailed information is required to properly evaluate your plans and the unique conditions of your property or unit:

Before you get started, consult the zoning by-law to ensure your proposed plans, proposed dimensions and parking availability are permitted under the Town of Oakville's zoning by-laws which regulate the use, shape and location of buildings on properties. Anytime there is a change of use for the building or unit, a Zoning Certificate of Occupancy is required.

If you are adding additional units (such as a basement apartment) to an existing home, it will likely be exempt from development charges. Two additional units can be added to a single or semi-detached home or townhouse without incurring development charges.

 Learn more about development charges, including current rates.

If your project is deemed substantial redevelopment, then planning approval is required. If you are opening a daycare centre, site plan approval may be required. Learn more about planning applications.

An approved fire route is required. Please contact the Oakville Fire Department by email at for more information.

If your property is in a designated conservation area, contact Conservation Halton for approval at or 905-336-1158. Learn more about conservation-related permitting and planning

In certain instances, approvals from additional agencies are required.

  • If your property is located close to a major highway as indicated in the MTO designated areas map you will require Ministry of Transportation approval.

Other considerations

Demolition activities may be eligible  for a reduction in property tax assessment under Section 357 of the Municipal Act which provides municipalities with the authority to cancel, reduce  or refund taxes based on specific criteria.

If you think you are eligible to apply for a property tax adjustment please complete the Application for Cancellation/ Reduction/Refund of Taxes under Section 357 form (pdf) and send to

Deadline for submission is the last day of February, the year following the issuance of a demolition permit. A $20.00 fee will apply. Learn more about property tax assessments