Additional residential unit (ARU) permits

Check whether you need a permit

• Before building an additional residential unit (ARU), you must obtain a building permit from the Town.
• Building an ARU requires compliance with zoning regulations and the Ontario Building Code.
• Depending on your property, you may also need supporting documentation and approvals before construction can begin.

Confirm property eligibility

Before planning an ARU, confirm that your property is eligible. Eligibility requirements differ depending on whether your property is located in Milton’s urban or rural areas.

• Not every property can accommodate an ARU, even if it is located in an area where ARUs are permitted.
• In January 2026, the Town updated its Official Plan and Zoning By-law to permit ARUs in rural areas where permitted by provincial policy.
• Detached houses
• Semi-detached houses
• Semi-link houses
• Townhouses (excluding stacked and back-to-back townhouses)
• Up to four residential units may be permitted on eligible property, including the primary dwelling and ARUs. ARUs may be located within the primary dwelling or in a detached building on the same lot. Only one ARU may be permitted in a detached building.
• Properties in urban areas without municipal water and/or sewer services in any low density residential zone may be permitted up to two ARUs, subject to applicable requirements.
• If your property is part of a condominium corporation, check with the condominium corporation to determine whether additional restrictions apply.
• One ARU may be permitted in a detached house, semi-detached house, townhouse, or accessory building on the same lot
• One ARU may be permitted within a detached dwelling in the Escarpment Rural Area Designation
• Detached ARUs are not permitted
• ARUs are not permitted on lots containing more than one house
• ARUs are not permitted in homes used for shared housing or as a Bed and Breakfast establishment
• ARUs are not permitted within the Greenbelt Natural Heritage System designation
• One ARU may be permitted in a detached dwelling or within an existing accessory building located outside the Greenbelt Natural Heritage System
• Up to two ARUs may be permitted per lot
• Only one ARU may be located in a detached accessory building

Review applicable zoning requirements

Before building an ARU, review the zoning requirements that apply to your property. Zoning requirements may affect:

• The location of the ARU
• The size of the ARU
• Parking requirements
• The placement of detached structures
• The Town’s Zoning By-laws establish the standards that apply to ARUs. If your proposal does not meet the zoning requirement, you may be able to apply for a minor variance.

Prepare required drawings and supporting documents0 of 4

To support your permit application, you may need the following documents:

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Complete the forms2Download the set2 forms

• Permit to Construct or DemolishForm
• Designer Information Form (Schedule 1)if the plans were not prepared by an architect or engineerForm

Upload your completed application package online

• Additional information may be required depending on the scope of the project.
• To help you understand the requirements for creating a second unit, review the Government of Ontario’s guide on building a second unit before submitting your application.
• Upload your completed application package online, including all supporting drawings and documents.

Pay the fee

• Secondary dwelling unit (detached): $25.13/m² (≈ $2.33 per sq ft) - Minimum $264.20
• Secondary dwelling unit (attached): $9.58/m² (≈ $0.89 per sq ft) - Minimum $264.20
• Once the building permit application package has been accepted, you will receive notification with an invoice for permit fees, including payment options. Permit fees are due upon receipt to begin the full permit review.