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On Oct. 7, 2026, the Town of Milton launched an updated website. The redesigned website improves how content is organized, displayed, and accessed, to help residents, businesses, and visitors get to the information they need faster. 

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Build an ARU

What's on this page 

↓Overview
↓Who this is for
↓Eligibility requirements
↓Zoning requirements
↓What you need
↓Before you apply
↓After your permit is issued
↓Next step
↓Related services

Overview 

Before building an additional residential unit (ARU), it's important to understand whether your property is eligible and what approvals are required. 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. 

The ARU registration program is currently operating as a three-year pilot that launched in 2025. If you choose to build an ARU, registration will be required once construction is complete. At the end of the pilot, the program will be reviewed, and registration and renewal requirements may change. 

Who this is for 

This page is for: 

  • Homeowners interested in creating an ARU on their property 

  • Homeowners planning a basement apartment, coach house, or detached ARU 

  • Property owners looking to understand zoning and permit requirements before construction begins 

Eligibility requirements 

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. 

ARUs are permitted on residential properties with municipal water and sewer connections that contain one of the following housing types: 

  • 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. 

In January 2026, the Town updated its Official Plan and Zoning By-law to permit ARUs in rural areas where permitted by provincial policy. 

Rural properties outside the Niagara Escarpment Plan Area 

On properties zoned RV or C4 outside the Niagara Escarpment Plan Area: 

  • One ARU may be permitted in a detached house, semi-detached house, townhouse, or accessory building on the same lot 

Rural properties within the Niagara Escarpment Plan Area 

On properties zoned RV or C4 within the Niagara Escarpment Plan Area: 

  • 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 

Properties within the Greenbelt Protected Countryside Area 

On properties zoned A1, A2 or RE within the Greenbelt Protected Countryside Area: 

  • 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 

A1 properties outside the Greenbelt Protected Countryside Area 

On properties zoned A1 outside the Greenbelt Protected Countryside Area: 

  • Up to two ARUs may be permitted per lot 

  • Only one ARU may be located in a detached accessory building 

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. 

What you need 

Before building an additional residential unit (ARU), you must obtain a building permit from the Town. 

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

  • A site plan 

  • Existing and proposed floor plans 

  • Construction details, including wall, ceiling and fire-separation information 

  • Drawings showing entrances and windows 

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. 

Before you apply 

  1. Confirm property eligibility 

  1. Review applicable zoning requirements 

  1. Prepare required drawings and supporting documents 

  1. Upload your completed application package online, including all supporting drawings and documents.

After your permit is issued 

Once your building permit is issued, construction of the ARU may begin. After construction is complete, you must register the ARU with the Town.

Next step: Register your ARU.

Related services