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:
- An Official Plan and Zoning Bylaw amendment to remove the bedroom limit per dwelling unit and increase permissions.
- An Official Plan and Zoning Bylaw amendment to add duplexes and triplexes as building types that permit ARUs.
Types of ARUs
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.
There are four (4) main types of ARUs:
Step-by-step planning guide:
1. Determine ARU type
Each ARU type has different requirements, and the information needed for a building permit is different.
There are four (4) main types of ARUs including:
- interior/basement conversion
- converted garage
- detached
- addition to existing building
2. Zoning compliance
Zoning review is completed by the City as part of the building permit process, but zoning regulations may impact the type of ARU you can create on your property.
ARUs are permitted when the zoning allows for single detached, semi-detached, or street townhouse dwellings, to a maximum of four (4) total units.
How to find your property's zoning
- Use CityMap to locate your property and the zone code.
- Links to each section of the Zoning By-law. The corresponding table of regulations is located at the end of each section. These regulations apply to the main building on the property.
Additional requirements for detached ARUs
If you are proposing a detached ARU, it will also need to comply with the Accessory Structure regulations in Section 4 – Section 4.1 Accessory Uses, and Section 4.37 Additional Residential Units are the relevant sections.
To confirm permitted uses and zoning regulations visit our zoning webpages, call 519-930-3510 or email zoning@london.ca
What if my property does not meet 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.
Important requirements when planning your ARU:
Key regulations
- ARUs are permitted on the same lot as a single detached, semi-detached, or street townhouse, duplex, triplex, or converted dwelling.
- A maximum of three (3) ARUs are permitted per lot. Two (2) of the additional residential units can be in a detached building.
- No additional parking is required for ARUs. Additional driveways to serve an ARU are not permitted.
- Detached ARUs can only be in the rear or interior side yard. (It cannot be in the front yard or between the main dwelling and the street on a corner lot)
- Detached ARUs must comply with the lot’s overall landscape open space and lot coverage requirements. The total combined footprint of all buildings on the property cannot exceed a percentage of lot area, and the lot must maintain a minimum percentage of landscaped open space that is not occupied by buildings or parking areas.
- A building permit and a residential rental unit license are required for all ARUs.
3. Building permit process
An approved building permit is required prior to any construction.
The property owner may submit their own plans or hire an architect or a qualified designer with a Building Code Identification Number (BCIN) to draft and sign the architectural floor plans for the proposed ARU.
A qualified heating, ventilation, and air conditioning (HVAC) designer with a BCIN must design the proposed HVAC layout and where pre-engineered roof trusses are proposed, the roof design must be stamped by a Professional Engineer.
There are different Ontario Building Code requirements depending on the project. 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.
4. 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.
5. Building and Fire Code
All construction must meet the requirements of the Ontario Building Code and Ontario Fire Code.
Applying for a building permit
Building permit requirements
When applying for a building permit, the following must be submitted:
1. Apply for a Permit to Construct or Demolish (15 business day review period).
2.Permit fee paid at permit submission, minimum $250.80 for 2024 applications.
3.Schedule 1: Designer Information Form completed by:
- A qualified designer, minimum “House” BCIN qualification required (designer declaration required on all drawings),
- The registered homeowner, or
- Architect or engineer (form not required when all drawings are stamped).
4.Letter of Authorization from owner
- Required if the applicant is not the same as the property owner.
5.Plot Plan, Site Plan or Survey (drawn to scale) that clearly shows the following:
- Location of existing/proposed buildings.
- All setbacks of new building or additions.
- Lot coverage (if new buildings or additions are added).
6.Construction drawings (single line drawings not acceptable, drawn to scale):
- Existing floor plans (all floors):
- Window/door sizes & locations, room names, stair location, wall locations and construction, etc. (for all floors).
- Proposed floor plans:
- New wall construction, fire separations (new and existing), new windows and doors, room names, plumbing locations for kitchen, bathroom and laundry, ceiling heights (overall, under beams and ducts), egress/exits, etc.
- Show accessory structure framing, plumbing, heating, etc. (if applicable).
- Elevations (applicable if adding egress windows/doors)
Whether a house is more or less than 5 years old, different parts of the Ontario Building Code apply. The designer working on your drawings should be aware of these requirements and include the relevant information with the application submission.
The City of London has specified that if the house is less than 5 years old, the original building permit must be closed.
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 and notes 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 ARUs in accessory buildings
- Number of Bedrooms in each unit
Documents required to apply for a building permit:
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.
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.
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.
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.
FAQs
How many ARUs can I have?
You can have up to four (4) total units on a residential property where the zoning permits single detached dwellings, semi-detached dwellings, or street townhouse dwellings. Only two (2) can be in a detached structure.
The total is determined by adding together the number of ‘original’ and ‘additional’ units.
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 designations added to your existing address, please create a service ticket with Canada Post by calling 1-866-607-6301.
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 no limit on the number of bedrooms permitted on a lot, except where the lot is located in the Near-Campus Neighbourhoods Special Policy Area.
Inside the Near-Campus Neighbourhoods Special Policy Area there is currently a maximum of five (5) bedrooms permitted within each dwelling unit.
Near-Campus Neighbourhoods are those near Fanshawe College and Western University. To determine if you fall within this area, please contact Planning and Development.
Information on Near Campus Neighbourhood can be found in the Zoning By-law Z.1, Section 4, Figure 4.36.
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.
Where can I find additional resources?
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.