Additional Dwelling Units (ADUs)

Looking to build an ADU? Learn how to get started!

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house with additional dwelling unit in background

What is an additional dwelling unit (ADU)?

An additional dwelling unit (ADU) is a separate living space within a home or on the same property as a house. These units typically have a kitchen, bathroom, living and/or dining area, and area to sleep. Examples of ADUs may include:

a basement apartment
an in-law suite
a backyard tiny home
a coach house
a laneway house

additional dwelling unit guidebook report cover

Is your property ready for ADU-over?

Download our step-by-step design and development guide to learn how to add ADUs to your property.
Download our quick and easy brochure to learn how to add an ADU to your property.

Why build an ADU?

Here are some of the benefits of ADUs:

increased housing supply without urban sprawl
source of rental income for the property owner
higher property value
provide independent living for family

What you need to know

Looking to build an affordable ADU? Apply for a grant today!

Our Affordable Housing Community Improvement Plan grants make it easier than ever to add an affordable unit to your home.

Learn more and apply today

Your ADU must comply with the regulations outlined in the Zoning Bylaw, such as:

where you can build
setbacks
height
size
parking
access requirements

You can check the Zoning Bylaw Amendment (December 10, 2024) for the latest regulations.

Design and construction must also conform with the Ontario Building Code to ensure health and safety standards are met.

What type of lots can accommodate an ADU: ADUs are allowed on the same lot as a(n):
- single-detached house
- semi-detached house
- duplex
- on-street townhouse
How many ADUs:
- Single-detached home? You can build up to three ADUs.
- Semi-detached home, duplex, or on-street townhouse? You can build up to two ADUs.
Where can I build: You can build ADUs in the following zones:
- 1 – Low density residential 1
- 2 – Low density residential 2
- 3 – Low density residential 3
- 5 – Medium density residential 5
- MOC – Mixed office/commercial
- 2 – Downtown 2

You can use our interactive online map to check the zoning of your property.

Types of ADUs

diagram of a house showing attic and basement additional dwelling units

Internal ADUs: Built inside the main home, this type of ADU makes the most of the space you already have. They are a great option if you want to add living space without doing major construction.

diagram of an additional unit in an existing home

Attached ADUs: This type of ADU is connected to the main home — like a suite over a garage or a home addition. It gives you extra space while still being connected to the house.

diagram of a detached additional dwelling unit

Detached ADUs: This type of ADU is in a separate building on your property — like a backyard cottage or suite above a detached garage. They often cost more to build due to their standalone nature.

Attached/Internal ADUs:

ADUs must be smaller than the primary dwelling unit.
If you need exterior stairs to units above the first floor, they are generally only allowed in the rear yard.
You do not need to have interior access between units.
There is no limit on the number of bedrooms.

Detached ADUs:

You can construct a building with up to two detached ADUs in a rear or interior side yard.
- If adding two detached ADUs, they must be in the same building.
- The building cannot take up more than 30 per cent of the yard. This includes other accessory structures.
- The building can be up to 6.1 metres tall (measured to the midpoint of the roof). This height allows for two storeys.
Each detached ADU can have a residential floor area of up to 80 m²(861 square feet). Please see the Zoning Bylaw for the definition of residential floor area.
If the building contains two ADUs, the building can have a floorplate of up to 90 square metres. Please see the Zoning Bylaw for the definition of floorplate.

Pedestrian access to your ADU

It’s important for people to easily access the entrance of the ADU, whether it is inside your main home or in a detached building.

Please ensure the pedestrian access (such as a walkway) meets the following regulations and guidelines:

Clear pedestrian access:
- must be at least 1.2 metres wide
- required for a separate entrance to an ADU
- not needed if access is provided directly from a street or lane
- clear of exterior stairs, window wells, air conditioners and other encroachments
- gates may be built within the pedestrian access
Grading and drainage:
- walkways and hardscaping (patio stones, concrete paths, garden walls) must be at least 0.6 metres from the property line
- setback must be kept as a landscaped strip
- pedestrian access must not change the grading and drainage patterns

Setbacks for detached ADUs

Thinking about building a detached ADU? It will need to be setback by specific distances from other structures and property lines. Please follow the guidelines below:

Interior side and rear yard setback (yards that do not abut the street): 1.5 or 1.2 meters for 1-storey or 2-storey buildings without windows on the side or rear, depending on the zoning of the property.
Interior side and rear yard setback with second-storey windows facing property lines: 3 meters.
Exterior side yard (corner lots that abut the street): 4.5 or 6 meters, depending on the property, but not less than the main building’s setback.
From main dwelling: 3 meters.
Any second-storey balcony, entrance or exterior stair to the second storey: 3 meters.

Parking

No additional parking is needed if there is only one ADU on your property. For each additional ADU, one more parking space is needed.

For example:

primary dwelling + 1 ADU = 1 parking space
primary dwelling + 2 ADUs = 2 parking spaces
primary dwelling + 3 ADUs = 3 parking spaces

If there is no legal off-street parking space for the primary dwelling unit, no parking spaces are required for ADUs.

Where does the parking space need to be?

All parking spaces must be:

on private property
at least 2.5 metres x 5.5 metres if outside (exterior parking space)
at least 3 metres x 6 metres if in a garage or carport (interior parking space)

The first parking space must be:

at least 6 metres back from the front property line
to the rear of the front wall of the main building
setback 0.5 metres from the side property line

Additional parking spaces can be stacked behind this first space.

Municipal fees

When you build an ADU, there may be fees to support the costs of growth. These fees may include:

municipal development charges
education development charges (set by the local school boards)
cash-in-lieu of parkland dedication fees

Helpful guide on ADU development charges

Here are some common questions related to these fees:

Development charges help the City of Guelph cover the costs of growth.
- As more people move to Guelph, there is:
  - more demand for water and wastewater services;
  - more cars, bikes, pedestrians or buses on the roads;
  - more calls to emergency services; and
  - more use of City facilities like libraries and community centres.
- Additional dwelling units—or ADUs—create new spaces for people to rent or call home. This adds to the demand for these services.
- Development charges are exempted, in certain instances, for ADUs built in Guelph. These exemptions are legislative requirements under the Development Charges Act. In some cases, development charges will apply to ADUs, such as when it is the third ADU (fourth unit), or if it is a second ADU in an ancillary (separate) building.
- In 2024, the City exempted $10.4 million in development charges for ADUs as required under the Development Charges Act. These exemptions are funded from property taxes and utility rates.
- The Development Charges Act also provides an exemption from development charges on ADUs that will be rented at an affordable rate.
- These affordable rates must align with the Provincial Government’s Affordable Residential Unit Bulletin over a 25-year period.
- ADUs rented at an affordable rate may also be eligible for the Additional dwelling unit grant, as part of the City’s Affordable Housing Community Improvement Plan.
- To learn more about the grants and see if your project is eligible, please visit our Affordable Housing Community Improvement Plan page.
- When building an ADU, municipal development charges will be required when you:
  - build a second ADU in a new or existing structure that is detached from the primary dwelling;
  - add a third ADU—or fourth unit—to your property. or
  - add any unit to a new or existing duplex or triplex.
- Education development charges may also apply in certain situations, as determined by the Education Act.
- Cash-in-lieu of parkland dedication is required in similar situations; however, there may be exceptions based on the lot’s history and previous contributions to parkland dedication.
- The timing of development applications can also make a difference.
- Where applications for ADUs are proposed one at a time, rather than all at once, cash-in-lieu of parkland dedication would not apply. This is the case even on the third ADU.
Yes! If ADUs are rented at an affordable rate for a period of 25 years, these units will be exempt from development charges and cash-in-lieu of parkland dedication.
- These units must be rented “at arm’s length,” meaning they must be rented to someone who is not related to the landlord/property owner.
- These affordable rates must align with the Provincial Government’s Affordable Residential Unit Bulletin over a 25-year period.
Yes! The Affordable Housing Community Improvement Plan provides grants for property owners who commit to rent the ADU at an affordable rate for a minimum of 15 years, according to the Provincial Government’s Affordable Residential Unit Bulletin.

Affordable units must be rented “at arm’s length” for 25 years to be exempt from development charges and cash-in-lieu of parkland dedication, meaning they must be rented to someone who is not related to the landlord/property owner.

Site services

Your property must have adequate water and wastewater capacity. ADUs must connect to municipal services, where available. Property owners are responsible for any costs for upgrading pipes to allow for an ADU. This includes both private property and within the right-of-way. To learn more, visit the Site Servicing: Installation, Replacement or Repair page.

Prepare to apply for a building permit

Are you getting ready to apply for a building permit for your ADU? Click on the link below that best describes your project to find:

what you need to submit
Ontario Building Code requirements
permit fees

Interior renovations to create one additional dwelling unit

diagram of house with multiple interior ADUs

Interior renovations to create multiple additional dwelling units

House with an addition to create one ADU

Build an addition to create one additional dwelling unit

Diagram of a house with an addition to create multiple ADUs

Build an addition to create multiple additional dwelling units

Build a detached additional dwelling unit or convert an existing detached building

Apply for a building permit

Ready to apply for your building permit? Follow the steps below to complete your application:

Go online to the Guelph Permit and Application System.
Register as a user.
Submit your building permit application. Please have all drawings and documents ready in PDF format.

After you submit your application, you can go back to the Guelph Permit Application System to:

check the status of your permit
pay fees
book inspections online

Register your ADU

You will need to register your ADU with the City. This includes new ADUs and those built without a permit.

Here’s how to register:

Apply for a building permit for your ADU.
Fill and sign the Small Multi-Unit Residential Registration form and submit with your permit application.
Pay the registration fee. This is billed when you apply for a building permit.

Registration fees:

Is the property occupied by the owner?	Per new ADU	Per existing ADU
Yes	$160	$320
No	$320	$640

You can read the full bylaw related to registering an ADU here: Small Multi-Unit Residential Registration Bylaw

Can’t find what you need?

For questions about building permits:
- Email [email protected] or call 519-837-5615 to contact Building Services.
For questions about zoning:
- Email [email protected] or call 519-837-5615 extension 4271 to contact Zoning Services.
For questions about servicing your property:
- Visit the Site Servicing: Installation, Replacement or Repair
- Email [email protected] or call 519-837-5604 to contact the City’s Engineering Services.
For questions about development charges:
- Email [email protected] or call 519-837-5610 to contact the City’s Finance Department.
For questions about applying for a minor variance, including process and fees:
- Visit guelph.ca/cofa.
- Email [email protected] or call 519-822-1260 extension 2524 to contact the City’s Committee of Adjustment Services team.
Have another question?
- Use this form to submit a question to the Building Services team.