An Additional Residential Unit (ARU) is a self-contained dwelling unit located within the same building, or on the same lot, as an existing residential unit. Self-contained means that it has its own kitchen and washroom facilities, and a separate entrance.
ARUs can be located within the interior of the existing house (for example in the basement), in an existing garage, or by constructing a detached tiny home on the property or as an addition to an existing building.
London is encouraging this form of residential development to improve housing diversity, affordability and sustainable land use.
The following will help make it easier to establish Additional Residential Units on existing properties:
- A proposed Official Plan and Zoning Bylaw amendment to revise or remove the bedroom limit per dwelling unit and increase permissions.
- A proposed Official Plan and Zoning Bylaw amendment to add duplexes and triplexes as building types that permit ARUs.
- Working with ARU manufacturers to pre-approve building permits for modular ARUs.
- Considering additional Community Improvement Plan (CIPs) programs that could result in incentives.
Types of ARUs
There are four (4) main types of ARUs including: interior/basement conversion, converted garage, detached and addition to existing building.
Frequently asked questions about the current process for planning and creating ARUs:
How many ARUs can I have?
You can have up to four total separate units on a residential property where the zoning permits single detached dwellings, semi-detached dwellings, or street townhouse dwellings.
The total is determined by adding together the number of ‘original’ and ‘additional’ units. For example: Your house could have a basement unit and then a 2-unit tiny home in the backyard, which would be 4-units on the single-family residential property.
Where can ARUs be built?
- convert space in your existing home (including your basement, attic or attached garage)
- build an addition on your existing home
- build a new detached dwelling on your property (including a ‘tiny home’)
- convert an existing shed or detached garage
What about zoning regulations?
The zoning by-law sets out the uses and regulations that apply to all properties in the city, including any ARU project. Zoning also includes detailed information about maximum floor area, building height, and required setbacks from property lines. Learn more about zoning uses and regulations.
What fees and costs are associated with ARUs?
There are costs associated with the building permit, purchasing building materials, and any professionals needed to do the work. The following list is not comprehensive, and subject to change depending on your specific cost, but some of the typical costs include:
Building Permit Fees
A building permit will be required for any new ARU. The cost of a building permit is determined by the project's size, the amount of work done, and the type of building being constructed or renovated. Learn more about building permits.
Rental License Fee
There is a licensing program for all rental units. The program's intent is to protect the health and safety of persons residing in residential rental premises. Licensing of ARUs will include inspections. Learn more about More information can be found at residential rental unit licenses.
Professional Fees
Depending on your project's nature, you may be required to hire a professional designer, architect, or engineer for a variety of processes including preparing your building permit drawings.
Development Charges
Development charges are used by the city to pay for the capital costs infrastructure that supports new developments. To encourage the supply of smaller housing units, the Province of Ontario has exempted certain ARUs from development charges, subject to specific conditions. Learn more about development charges.
To determine whether development charges apply to your ARU project and the amount email building@london.ca or call 519-661-4555
Are there any City programs to help offset the cost of planning, construction, or operation?
Currently there are currently two programs available:
Affordable Housing Community Improvement Plan
We operate an ARU loan program available throughout the city, for homeowners interested in constructing an ARU. The program provides an interest free loan of up to $20,000 for constructing a new ARU.
Learn more about Community improvement and incentives.
Affordable Housing incentives
We also administer the Ontario Renovates Program which provides loans and grants for eligible repairs and accessibility modifications.
Learn more about housing programs and services.
The City is currently assessing opportunities for new grant and incentive programs.
Will an ARU affect my property taxes?
Yes, your property taxes will increase when you create an ARU. General information regarding assessment and property taxes is provided by the Municipal Property Assessment Corporation (MPAC).
How do I connect to water, sewer, electricity, gas, etc.?
You will need to contact the appropriate service providers and, in some cases, a qualified professional that can advise if your current service connections can accommodate the increase in service use, or if you will need to pay to have your services upgraded. In most cases, you should be able to connect through the existing dwelling and/or directly to the street.
Listed below are some of the service providers:
- City Water and Sewer: Email PlanDev@london.ca or call 519-930-3500
- Electrical Services: London Hydro
- Natural Gas Services: Enbridge Gas
Can I use a shipping container for an ARU?
Yes, a shipping container can be converted into an ARU. However, it must meet all the Building Code, Zoning By-law, and other regulatory requirements (including obtaining a building permit before starting construction), just like any other dwelling. A modified shipping container will need to be designed by a professional engineer (including the foundation).
In some cases, there may be a Canadian Standards Association (CSA) approval on the design which may supersede local Ontario Building Code standards.
Does my ARU need a separate address?
No, a new municipal address will not be required for ARUs created on the same property as an existing dwelling. However, a new unit number must be created to ensure the safety of people residing in all dwelling units. To have new unit number(s) added to your existing address.
For more information email plandev@london.ca or call 519-930-3500
Do I need insurance on my ARU?
Yes, you will need to contact your individual property insurance provider for quotes and information on coverage for your ARU.
Can an ARU be severed and sold separately?
An ARU provides an additional unit on a property where a primary dwelling unit already exists. There may be opportunities for severance in settlement areas in specific situations, evaluated on a case-by-case basis.
How much will my building permit cost?
A building permit will be required for any new ARU. The cost of a building permit is determined by the size of the project, the amount of work done, and the type of building being constructed or renovated. Learn more about building permits.
Is there a minimum size for a dwelling unit?
The Ontario Building Code specifies the minimum size for any dwelling unit, whether it is existing or additional. For a bachelor style ARU (where the sleeping, living, dining, and kitchen areas are combined as one space) a minimum floor area of 17.5 m2 is required.
What can I do if my property does not meet the zoning regulations?
If your property or project does not meet the requirements of the zoning by-law you may apply for a minor variance or a zoning by-law amendment to change the regulations if you cannot change your project plans.
Planning staff will review your project to determine if a minor variance is appropriate, or if the proposal requires a full by-law amendment. Learn more about planning and development applications.
How many bedrooms are permitted in ARUs?
There is currently a maximum of five (5) bedrooms within one single detached, semi-detached, or street townhouse dwelling for properties outside of the Near Campus Neighbourhoods (NCN) special policy area. These neighbourhoods are located near Fanshawe College and Western University. To determine if you fall within the NCN area, please contact Planning and Development.
Different housing types can have different bedroom limits depending on their legal description and location.
Structure types and bedroom limits
Different housing types can have different bedroom limits depending on their legal description and location:
| Structure type | Maximum bedrooms ** (Existing Building) **Subject to other zoning and Ontario Building Code regulations | Current ARU regulations (4 units/lot) |
|---|---|---|
Single-detached, Semi-detached, Street Towns (1 unit) | 5 | +3 permitted, max 5 bedrooms/property |
| Duplex (2 unit) | 10 (6 in near-campus neighbourhoods) | +2 permitted, max 5 bedrooms/property (interpreted as a single-detached) |
| Triplex (3 unit) | 15 (9 in near-campus neighbourhoods) | +1 permitted, max 5 bedrooms/property (interpreted as a single-detached) |
Information on Near Campus Neighbourhood can be found in the zoning by-law Z.-1 - Section 4, Figure 4.36.
Important requirements when planning your Additional Residential Unit:
- Zoning (Structure type): ARUs are permitted when the zoning allows for single detached, semi-detached, or street townhouse dwellings, to a maximum of four (4) total units.
- Zoning (Location): ARU locations, as shown in the image above, are also controlled by the zoning by-law using setbacks, coverage, and other regulations. To confirm permitted uses and zoning regulations visit our zoning webpages, call 519-930-3510 or email zoning@london.ca
- Zoning (Site Layout Plan): Concurrent with the building permit application, the site layout plan of the property drawn to scale will be required, that clearly shows the following:
- Location of existing/proposed buildings
- All setbacks of new buildings or additions
- Lot coverage (if new buildings or additions are added)
- Landscape open space coverage (if new buildings or additions are added)
- Parking area location
- Parking area coverage (if parking area is expanded)
- Sewer connection for new ADUs in accessory buildings
4. Zoning/Building - (Architectural drawing): Concurrent with the building permit application, an architectural drawing will be required, that clearly shows the following:
- Height of new buildings or addition
- Number of units
- Number of bedrooms in each unit
- Confirmation that the finished floor level of basement is below the level of any sanitary sewer servicing the building or structure in which the basement is located.
5. Servicing: Water and sewer servicing must be able to accommodate the increased residential development you want to build. To confirm servicing call 519-930-3500 or email PlanDev@london.ca
Note: Internet, phone, gas, and electricity are not services delivered by the City of London. Please contact you local utility provider.
6. Building and Fire Code: All construction must meet the requirements of the Ontario Building Code and Ontario Fire Code.
7. Building permit: An approved building permit will be required prior to any construction.
There are different Ontario Building Code requirements depending on renovating a house to create the new unit, putting an addition on your house, converting an accessory structure, or building a completely new detached accessory building. Different properties and building types will have different submission requirements and fees.
If you need assistance with your building permit application, please email building@london.ca or call 519-661-4555.
What are the complete building permit requirements for ARUs?
Documents required for ARU within existing house
- Schedule 1 Designer Information Form filled out by a qualified designer or the homeowner.
- Existing floor plans for all floors within the house.
- Proposed architectural floor plans for the new ARU signed by the Schedule 1 designer.
Please note: Additional documentation may be requested at time of application.
Documents required for ARU with addition to existing house
- Schedule 1 Designer Information Form filled out by a qualified designer or the homeowner.
- Proposed plan showing the location of the proposed addition.
- Existing floor plans for all floors within the house.
- Proposed architectural plans signed by the Schedule 1 designer including:
- Proposed foundation plan
- Proposed floor plans
- Elevations
- Wall/Building Sections
- Energy Efficiency Design Summary (EEDS) form completed by the Schedule 1 designer.
- Schedule 1 HVAC Designer form filled out by a qualified BCIN HVAC designer.
- HVAC packages complete with heat loss/gain calculations and HVAC layout completed by a qualified BCIN HVAC designer.
- TJI floor joist package complete with member reports stamped by a Professional Engineer and floor joist layout signed by the Schedule 1 designer. (Only required if using pre-engineered TJI floor joists.
- Roof truss package complete with truss member reports stamped by a Professional Engineer and truss layout signed by the Schedule 1 designer. (Only required if using pre-engineered roof trusses)
Please note: Additional documentation may be requested at time of application.
Documents required for converting an existing detached structure
- Schedule 1 Designer Information Form filled out by a qualified designer or the homeowner.
- Proposed plan showing the location of the existing detached structure being converted to an ARU.
- Proposed architectural plans for the new ARU signed by the Schedule 1 designer including:
- Proposed floor plan
- Elevations
- Wall/Building Sections
- Energy Efficiency Design Summary (EEDS) form completed by the Schedule 1 designer.
- Schedule 1 HVAC Designer form filled out by a qualified BCIN HVAC designer.
- HVAC packages complete with heat loss/gain calculations and HVAC layout completed by a qualified BCIN HVAC designer.
Please note: Additional documentation may be requested at time of application.
Documents required when constructing a new detached ARU
- Schedule 1 Designer Information Form filled out by a qualified designer or the homeowner.
- Proposed plan showing the location of the newly proposed detached ARU.
- Proposed architectural plans for the new detached ARU signed by the Schedule 1 designer including:
- Proposed foundation plan
- Proposed floor plans
- Elevations
- Wall/Build
- Energy Efficiency Design Summary (EEDS) form completed by the Schedule 1 designer.
- Schedule 1 HVAC designer form filled out by a qualified BCIN HVAC designer.
- HVAC packages complete with heat loss/gain calculations and HVAC layout completed by a qualified BCIN HVAC designer.
- Roof truss package complete with truss member reports stamped by a Professional Engineer and truss layout signed by the Schedule 1 designer. (Only required if using pre-engineered roof trusses.
Please note: Additional documentation may be requested at time of application.
Information and links provided on this page reflect the current process for planning and creating ARUs in London. This information is subject to change as staff work to make amendments to better facilitate the creation of ARUs. Each ARU project is unique, and applicants are urged to review all information and contact us if you have questions.