Additional Residential Units

Additional Residential Units (ARU)

An ARU, or also known as Additional Dwelling Unit (ADU), Granny Suite, In-Law Suite, Basement Apartment, is a residential dwelling unit completely self-contained and subordinate to and located within the same building and/or on the same lot as the primary residential unit, where a primary residential unit is a single detached, semi-detached or townhouse dwelling.

In the Oak Ridges Moraine Area, an ARU is permitted only within the same building as the primary residential unit, being a single detached dwelling.

All ARUs must include the following areas that are separate from the primary residential unit: a separate entrance, kitchen facilities, washroom facilities, and living space.

On this page:

Additional Residential Unit Register

Registering my ARU

All ARUs must be registered under By-law 2020-162. Unregistered ARUs are considered illegal. Units previously registered under Town of Lindsay By-law 97-169 and City of Kawartha Lakes By-law 2014-305 are deemed compliant.

The purpose of the Registration By-law is to ensure that all ARUs in Kawartha Lakes are safe and legal. The Registration By-law allows the City to maintain a complete inventory of all single detached dwellings, semi-detached dwellings and townhouse dwellings that contain ARUs, which will be used, for example, by emergency services agencies (i.e. Fire, Police, EMS) when responding to emergencies, the City’s Solid Waste Division for garbage pickup and the City’s Planning Division when calculating dwelling unit densities of neighbourhoods.

An application for registration of additional residential units must be filed with accompanying paperwork and applicable fee to the Building and Septic Division. Please note that where more than one ARU is proposed on a lot, each ARU must be registered individually.

There is a one-time fee required to accompany the application for registration, which can be found in the Consolidated Fees By-law 2024-037. There will also be associated building permit fees applied, if a building permit is deemed by Building and Septic Division staff to be required, with respect to required upgrades or new construction.

As part of the registration process, an inspection will be required to ensure the safety of the owner and tenants of the ARU. The inspection may be performed by a Building Inspector or by a Building Inspector in conjunction with a Fire Prevention Officer. The inspector(s) will confirm compliance with applicable regulations and will require access to all areas within all dwelling units.

Once an ARU is registered, the owner will receive a letter of registration from the City.

Guide for Additional Residential Units

Additional Residential Unit Registration Application Portal Guide

Additional Residential Unit Registration Application Portal

Building Permit and ARUs

In most cases, a building permit will be required to establish an ARU. Most ARUs will require modifications with respect to the Ontario Building Code to comply with registration requirements. A building permit considers items such as access/egress, suite to suite fire separations, room sizes, window sizes, locations of smoke detectors and carbon monoxide detectors and any other items applicable to your site. The property owner or a qualified designer can prepare the drawings required as part of the building permit application. Drawings must include all Ontario Building Code requirements. Upon submission of a complete application, a building permit will be issued within 10 business days.

Overview of regulations relating to ARUs

(a) Ontario Building Code:

Please refer to the Ontario Building Code for exact provisions relating to ARUs. The

following is for information purposes only.

Items associated with an ARU, including but not limited to the following, must comply

with the Ontario Building Code:

• Fire separations between dwelling units, between dwelling units and common;
• spaces such as exit corridors, laundry rooms and other spaces that are accessible by all dwelling units;
• Exits from each dwelling unit;
• Smoke alarms on each floor level in each dwelling unit, and carbon monoxide detectors; and
• Heating and ventilation system requirements.

ARUs proposed on properties serviced with a private on-site sewage system will require a review of the existing system components and capacities. In many cases, the existing sewage system will not be adequate for the increased usage and a new sewage system or upgraded sewage system will be necessary. Contact the Building and Septic Division – Sewage System Area Inspector to initiate a discussion around the requirements for applications and permitting for private on-site servicing.

(b) Zoning By-law:

If you would like to look up your own zoning, please visit City Maps to look up your property on the map and visit the Planning and Development Page to review the applicable zoning by-law.

General requirements for ARUs:

• The ARU complies with the Ontario Building Code, Fire Code, Zoning By-law and any other municipal and provincial standards
• The lot has adequate sewage and water supply
• On private services, lot area is at least 0.4 hectares
• The lot fronts on and has access to an improved public street, maintained year-round
• The lot is not used for a bed and breakfast establishment
• The primary residential unit meets the parking requirements in the Zoning By-law
• Floor area of an ARU is equal to or less than the floor area of the primary residential unit
• Up to two ARUs for every primary residential unit, where either one ARU is located within the same building as the primary residential unit and the other ARU is in an accessory building or two ARUs are located in the same building as the primary residential unit.
• Within the Oak Ridges Moraine Area, a maximum of one ARU may be located in the same building as the primary residential unit, being a single detached dwelling - detached ARUs are not permitted
• ARU is not located within the EP Zone, HL Zone, OS Zone, ORMCA Zone, ORMLA Zone, ORMEP Zone, floodplain area, water setback or other hazardous lands
• ARU complies with the Minimum Distance Separation formulae from neighbouring livestock barns, manure storages and/or anaerobic digesters
• Where ARU is located on an upper storey of an accessory building or structure, the height of the accessory building or structure may be increased to 10m and be located no less than 1.2m from side and rear lot lines

(c) Ontario Fire Code:

Please refer to the Ontario Fire Code for exact provisions relating to additional residential units. Below is for information purposes only.

ARUs must comply with the following items under the Ontario Fire Code, including but not limited to:

• Fire separation from each dwelling unit
• Means of escape from each dwelling unit
• Smoke alarms
• Electrical safety

Property owners should be aware that bringing existing dwellings that contain an ARU into compliance with the Ontario Fire Code regulations may require alterations for which a building permit is required under the Building Code Act.

Agency Contact Information

Building and Septic Division: 705-324-9411 extension 1288 or e-mail buildingpermits@kawarthalakes.ca

Fire Prevention Division: 705-324-9411 extension 3650 or e-mail fireprevention@kawarthalakes.ca

Electrical Safety Authority: 877-372-7233 or visit their website.

To locate a qualified designer, use the Ministry of Municipal Affairs and Housing QuARTS registration site.

In 2019, the Province of Ontario released a homeowner guide adding a Second Unit in an Existing House to help homeowners plan and build a second unit within their house. Please note that while the legislation has been amended to replace Second Units with ARUs, the guide continues to be helpful in explaining the Building Code requirements for adding additional units on a lot.

Frequently Asked Questions

How do I obtain an address/sign for my ARU?

Upon completion of registration, a municipal address will be assigned to the ARU. It is the owner’s responsibility to display the address for the ARU so that in urban areas, it is visible from the street and in rural areas, directional arrows direct Emergency Services personnel to the entrance to the unit and the location of the unit is clearly indicated on the building face visible upon approach down the driveway.

Can my tenant park on the street?

Please be aware that vehicles illegally parked on the street will be ticketed and no exceptions will be made for ARUs. Before creating an ARU, please consider the parking needs for all units and ensure the combined parking needs can be  accommodated wholly on the subject property.

Can I sever an ARU from the primary residential unit?

An ARU within an accessory building or structure is not eligible for a severance from the primary residential unit. An ARU, by definition, must be located on the same lot as its primary residential unit.