Additional Residential Unit

Additional residential units (ARUs) are permitted in the City of Richmond Hill, subject to zoning requirements and restrictions, including a building permit.

An ARU is a self-contained unit with a private kitchen, bathroom facilities and sleeping areas in:

a main residential building (such as a single detached house, semi-detached house or townhouse) and/or
a separate building (such as above a detached garage) on the same property.

ARUs have also been referred to as secondary suites, basement apartments, two-unit dwellings, granny flats, in-law suites, accessory apartments, laneway houses, coach houses, garage suites and garden suites.

What You Need to Know

Zoning Regulations
The City of Richmond Hill has passed By-law 143-24 on December 11, 2024 under section 34 of the Planning Act, R.S.O. 1990. The purpose and effect of this amending Zoning By-law 143-24 is to permit Additional Residential Units (ARU) within any zone that permits single detached dwellings, semi-detached dwellings and certain forms of townhouses and other dwelling types with certain restrictions. A maximum of three (3) Additional Residential Units shall be permitted on a lot in addition to the primary dwelling unit, provided the total number of dwelling units per lot does not exceed four (4) and provided the number of Additional Residential units in an Accessory Residential Building does not exceed two (2) subject to the appropriate development standards. The lot or parcel is required to be separately serviced by municipal sewage works and drinking water system. All applicable law, as set out by the Ontario Building Code, still applies. For all requirements and restrictions refer to By-law 143-24, on file with the Office of the Clerk.
Applying for a Building Permit
Before you apply for a building permit, it is important to note: Drawings by qualified professionals Drawings required as part of the building permit application should be prepared and reviewed by a qualified professional as outlined in the Ontario Building Code. A qualified professional can be an architect, professional engineer or a BCIN qualified designer. Delays in the issuance of your permit can arise if your drawings are not complete and/or do not conform to the OBC and the applicable laws. Building permit submissions for a newly proposed ARU. You must submit: Building Permit Application Form Schedule 1 Designer Information Form Compliance with Applicable Laws Form Executed Site Plan Agreement from Development Planning (for properties within site plan control area) Site Alteration Permit form Development Engineering (if the new accessory structure is greater than 400 sf) TRCA Approval (for properties within regulated area) Site plan, floor plans, elevations, sections and details (stamped/sealed by a qualified professional) Mechanical drawings, including Energy Efficiency Design Summary and heat loss and heat gain calculations Applicable building permit fee Apply for a building permit.
Pre-Approved Detached ARU Plans
City of Richmond Hill Pre-Approved ARU Permit Plans The City of Richmond Hill now offers a pre-approved detached Additional Residential Unit (ARU) model to help streamline the building permit process. Click here to view our pre-approved detached ARU model, which can be used as part of building permit submission. These approved plans comply with the Ontario Building Code and may be used, in conjunction with a site-specific Site Plan drawing, to apply for a detached ARU dwelling unit. Please be advised that a proposed Site Plan is still required. The Site Plan must show the existing lot dimensions, existing building locations (i.e. house, garages, sheds, etc.), the proposed location of the pre-approved ARU building (which is approximately 6.64m x 5.47m), and existing and proposed setbacks to all property lines for all buildings. Refer to our Site Plan Guide for a sample Site Plan and guidance on the required information to help streamline your permit review. All Building Permit applications made with pre-approved plans must be submitted with a completed Pre-Approved Reference Model Declaration Form. Have additional questions related to the City of Richmond Hill Pre-Approved ARU Permit Plans? Please email us at Building@RichmondHill.ca. For information on fees, submission requirements, and how to apply for a building permit, visit our Building Permit home page.
Booking a Building Inspection
Once the building permit has been issued, construction can begin. As required by the Ontario Building Code, a building inspector must review the work at various stages of construction. The property owner or his/her agent is responsible for notifying the City's Building Division when different stages of construction are ready for inspection. You can book an inspection by completing the Inspection Request Form. Once all inspections are completed, an Occupancy Permit will be issued.

Zoning Regulations

The City of Richmond Hill has passed By-law 143-24 on December 11, 2024 under section 34 of the Planning Act, R.S.O. 1990.

The purpose and effect of this amending Zoning By-law 143-24 is to permit Additional Residential Units (ARU) within any zone that permits single detached dwellings, semi-detached dwellings and certain forms of townhouses and other dwelling types with certain restrictions.

A maximum of three (3) Additional Residential Units shall be permitted on a lot in addition to the primary dwelling unit, provided the total number of dwelling units per lot does not exceed four (4) and provided the number of Additional Residential units in an Accessory Residential Building does not exceed two (2) subject to the appropriate development standards.

The lot or parcel is required to be separately serviced by municipal sewage works and drinking water system.

All applicable law, as set out by the Ontario Building Code, still applies.

For all requirements and restrictions refer to By-law 143-24, on file with the Office of the Clerk.

Applying for a Building Permit

Before you apply for a building permit, it is important to note:

Drawings by qualified professionals

Drawings required as part of the building permit application should be prepared and reviewed by a qualified professional as outlined in the Ontario Building Code. A qualified professional can be an architect, professional engineer or a BCIN qualified designer. Delays in the issuance of your permit can arise if your drawings are not complete and/or do not conform to the OBC and the applicable laws.

Building permit submissions for a newly proposed ARU.

You must submit:

Building Permit Application Form
Schedule 1 Designer Information Form
Compliance with Applicable Laws Form
Executed Site Plan Agreement from Development Planning (for properties within site plan control area)
Site Alteration Permit form Development Engineering (if the new accessory structure is greater than 400 sf)
TRCA Approval (for properties within regulated area)
Site plan, floor plans, elevations, sections and details (stamped/sealed by a qualified professional)
Mechanical drawings, including Energy Efficiency Design Summary and heat loss and heat gain calculations
Applicable building permit fee

Apply for a building permit.

Pre-Approved Detached ARU Plans

City of Richmond Hill Pre-Approved ARU Permit Plans

The City of Richmond Hill now offers a pre-approved detached Additional Residential Unit (ARU) model to help streamline the building permit process.

Click here to view our pre-approved detached ARU model, which can be used as part of building permit submission. These approved plans comply with the Ontario Building Code and may be used, in conjunction with a site-specific Site Plan drawing, to apply for a detached ARU dwelling unit.

Please be advised that a proposed Site Plan is still required. The Site Plan must show the existing lot dimensions, existing building locations (i.e. house, garages, sheds, etc.), the proposed location of the pre-approved ARU building (which is approximately 6.64m x 5.47m), and existing and proposed setbacks to all property lines for all buildings. Refer to our Site Plan Guide for a sample Site Plan and guidance on the required information to help streamline your permit review.

All Building Permit applications made with pre-approved plans must be submitted with a completed Pre-Approved Reference Model Declaration Form.

Have additional questions related to the City of Richmond Hill Pre-Approved ARU Permit Plans? Please email us at Building@RichmondHill.ca.

For information on fees, submission requirements, and how to apply for a building permit, visit our Building Permit home page.

Booking a Building Inspection

Once the building permit has been issued, construction can begin. As required by the Ontario Building Code, a building inspector must review the work at various stages of construction. The property owner or his/her agent is responsible for notifying the City's Building Division when different stages of construction are ready for inspection.

You can book an inspection by completing the Inspection Request Form.

Once all inspections are completed, an Occupancy Permit will be issued.

Contact us for more information

Zoning By-law

Zoning By-law Inquiry Form

Building Permit

Email building@richmondhill.ca or call 905-771-8810.

Building Inspection

Email buildinginspections@richmondhill.ca or call 905-71-5465.

Electrical Safety Authority

The property owner must attain a separate electrical permit for electrical work from the Electrical Safety Authority (ESA) as the Electrical Safety Code has further requirements when adding an ARU. For additional information, call 1-877-ESASAFE (372-7233).

Violations and complaints

If you are concerned that an ARU has been established without the benefit of a building permit or is not in compliance with the Ontario Building Code, please email buildinginspections@richmondhill.ca

If you have a complaint about your landlord or your tenant, contact the Landlord and Tenant Board at 1-888-332-3234.

Additional Information

When considering whether establishing an ARU is right for you, please refer to the following resources: