Additional Dwelling Units

Additional Dwelling Units (ADU), also referred to as secondary suites, basement apartments, two-unit dwellings, granny flats, in-law suites, accessory apartments, laneway houses, coach houses, garage suites or garden suites; are classified as either Principal Residence (apartments inside a principal residence) or Detached (secondary suites). ADUs are units with at least two rooms, with bathroom facilities and space for cooking or room to add cooking equipment.

If you are considering whether an ADU is right for you, please refer to the following resources provided by the Ministry of Municipal Affairs and Housing (MMAH):

ADUs/Accessory Apartments are allowed in the Town of Whitby in certain single detached and semi-detached homes. Review the Official Plan and Zoning By-law to learn more about the regulations. To verify if an ADU/Accessory Apartment is permitted on your property, please Submit a Planning Inquiry.

The Town of Whitby has pre-approved designs for Detached Accessory ADUs/Accessory Apartments. These designs already meet the Ontario Building Code, making it faster and easier to get a Building Permit.

Learn more

An incentive program is available from April 1, 2024 to December 31, 2025 supported by the Town's Housing Accelerator Funding.

Incentive Program - Town's Housing Accelerator Funding

Property owners who successfully obtain a building permit for an Additional Dwelling Unit (ADU)/Accessory Apartment during the program have the option of entering into an "Additional Dwelling Unit Incentive Agreement" with the Town. The incentive is an equivalent payment to the property owner of select Town fees related to their ADU/Accessory Apartment work upon successful permit issuance. The select fees include, where applicable, ADU Building Permit Fees, Accessory Apartment Registration Fee, Curb Cut Fee, Development Charges for Education. The ADU/Accessory Apartment must be registered with the Town of Whitby By-Law Services by March 31, 2027* to align to Housing Accelerator Fund timelines. If you wish to participate please email HAF-ADU@whitby.ca.

You are eligible to receive an Additional Dwelling Unit Incentive if you meet the following criteria:

You are the registered owner of a residential property located in the Town of Whitby;
You have submitted a complete** building permit application for an ADU/Accessory Apartment at your property on or before December 31, 2025;
You have paid all fees and charges required to be paid for the ADU/Accessory Apartment;
You have been issued a building permit for the ADU/Accessory Apartment after April 1, 2024; and
You enter into an Additional Dwelling Unit Incentive Agreement with the Town.

Note:

*The Additional Dwelling Unit must be registered as an Accessory Apartment with the Town of Whitby By-Law Services on or before March 31, 2027. If the ADU is not registered with Town of Whitby By-Law Services by March 31, 2027, the Owner shall pay back to the Town the amount paid as an incentive by April 30, 2027. It is the responsibility of the applicant to ensure that they request and schedule any and all required final inspections well in advance of March 31, 2027 in order to ensure that there is sufficient time to complete all required inspections, remedy any outstanding issues as may be required, and scheduling any necessary re-inspections.

**Submissions should be made at least two weeks prior to December 31^st and must be deemed complete no later than December 31, 2025. If a Minor Variance for zoning is required and has not yet been completed then the submission is deemed "incomplete". The Minor Variance decision must be final and binding at the time of a complete building permit application.

There will be no exceptions or extensions to these deadlines.

Apply for an ADU - Additional Dwelling Unit building permit

The Town of Whitby accepts Residential Building Permit applications through the following methods:

E-Portal
Email
In-person (printed document)

While all three methods are acceptable, the Town strongly recommends the use of E-Portal as the preferred method.

Before submitting your application, please review the E-Portal Submission Standards or Electronic Building Permit Submission Standards (email). These documents explain how to properly prepare your digital documents and drawings.

When uploading documents to the E-Portal or sending files via email, the Town requests your assistance in adopting a standardized file naming convention. This will help streamline the review process and minimize the risk of misplaced information. Please refer to the File Naming Convention document for more information.

Building Permit Application Options

Option 1 - E-Portal Submission (Pre-screening)

You can upload all required documents and drawings through the E-Portal. Your application will undergo a pre-screening process. Once approved, instructions for the next steps, along with the invoice to make a payment via credit card will be provided via email.

Option 2 - Email Submission (Pre-screening)

You can submit your documents and drawings via email. Your application will undergo a pre-screening process. Once approved, instructions for the next steps, along with the invoice to make a payment via credit card will be provided via email.

Option 3 - Paper Submission (Pre-screening)

For Non-residential Building Permit Applications and subdivisions, submit your application in person for pre-screening to:

Town of Whitby – Building Services Division
3050 Garden St. Unit 102
Whitby, ON L1R 2G7

Required Inspections

You need to receive the following inspections for Additional Dwelling Units (ADUs)/Accessory Apartments. Please contact:

Contact a Licensed Electrical Contractor (LEC) to verify compliance with the Ontario Electrical Safety Code. After the assessment they can provide you with a Certificate of Acceptance. Read the instructions on submitting a Certificate of Acceptance.
Contact Fire and Emergency Services to ensure the apartment meets the regulations in the Ontario Fire Code.
Once you have submitted your Certificate of Acceptance, and all required building permits have been obtained as part of the Accessory Apartment Registration, Enforcement Services will conduct an exterior inspection of the lands.

Some inspections may cost an additional fee.

Register an accessory apartment

$257.00 to register an ADU/Accessory Apartment
$510.00 to register an ADU/Accessory Apartment discovered due to a complaint
$102.00 to transfer the registration permit

Submit a Certificate of Acceptance

There are two options to obtain a Certificate of Acceptance.

Your Licensed Electrical Contractor (LEC) can provide you with a Certificate of Acceptance, although there is no prescribed form, the Certificate of Acceptance should contain:
- the ECRA/ESA licence number;
- the property address;
- a notice/inspection date (the inspection date must be within a reasonable timeframe of original installation);
- location of inspection;
- a customer ID number; and
- a general statement to certify the that electrical installation at the address was done in accordance with the requirements of the Ontario Electrical Safety Code.
If you are unable to receive a copy from your LEC, you can complete and return the Access to Information form from the ESA website and email the completed application to RFI@electricalsafety.on.ca.

After the Certificate of Acceptance has been received, Enforcement Services will conduct an exterior inspection of the lands.

Risks to a landlord for an illegal or unsafe ADU/Accessory Apartment

The following risks exist for landlords operating unsafe ADU/Accessory Apartment:

Increased liability

The responsibility is on the homeowner to meet established standards for all accessory apartments. If anything happens, such as a fire, the homeowner may be found liable due to the failure to meet legal requirements.

Loss of insurance coverage

Having a rental unit in your home is a material change to your home. If you don't disclose this to your insurance provider, it may cause your insurance coverage to be null and void.

Limited recovery of damage

An insurance policy is not typically responsible for rebuilding costs related to meeting current established standards. Your insurance company may only be required to cover the cost to fix your home back to the state it existed at the time your policy commenced prior to damage.

Prosecution

You are breaking the law if your building doesn't comply with:

You run the risk of being charged and you may face fines or imprisonment depending on the severity of the infraction.

Financing

Income from an illegal ADU/Accessory Apartment may not be considered when applying for a mortgage loan.

Tenants

As a landlord, you are obliged to maintain your ADU/Accessory Apartment in good operating order and you must follow all fire safety laws. Tenants may apply for rent reduction through the Landlord Tenant Tribunal where the unit fails to meet the prescribed municipal health, maintenance and property standards.

Tenant insurance

Your homeowner's insurance policy may not cover property owned by a tenant.

Frequently asked questions

View the frequently asked questions about ADUs/Accessory Apartments.

What is the difference between an Additional Dwelling Unit (ADU) and an Accessory Apartment?

The terms 'Accessory Apartment' and 'Additional Dwelling Unit' refer to the same housing concept: units with at least two rooms with bathroom facilities and space for cooking or room to add cooking equipment.

Accessory Apartment is often used in older by-laws or zoning regulations. ADU is a term used in more modern planning and zoning contexts. ADU encompasses various types of secondary residential units such as: secondary suites, basement apartments, two-unit dwellings, granny flats, in-law suites, laneway houses, coach houses, garage suites or garden suites.

What is an ADU/Accessory Apartment?

An accessory apartment is a room or a suite of two or more rooms, designed or intended for use by a person or persons, in which sanitary conveniences are provided and in which facilities are provided for cooking or the installation of cooking equipment.

Do development charges apply to ADUs/Accessory Apartments?

Development Charges for an ADU/Accessory Apartment in an existing home, or in a new home currently being built, would not apply as long as the unit meets the requirements under O.Reg 454/19.

Education Development Charges for the Durham District School Board and Durham District Catholic School Board would still apply for all ADUs/Accessory Apartments, if the original home was recently constructed and has been occupied less than 12 months.

What if I don't register my ADU/Accessory Apartment or don't do the work in the inspection report?

The Fire Department and By-law Services my lay charges and prosecute the owner of an illegal ADU/Accessory Apartment.

What requirements are in the Property Standards By-law to ensure the owner of an ADU/Accessory Apartment maintains their property?

The Property Standards By-law requires that all property owners in Whitby maintain the exterior property area around any building to ensure it is safe and in good repair. It also requires property owners to maintain minimum occupancy standards to ensure a safe living environment for tenants.

Will there be a regular follow-up inspection of all ADUs/Accessory Apartments once they are registered?

Enforcement staff will rely on requests for investigation at specific addresses from complaints we receive. Complaints may be received by a resident in the area or from a tenant of one of the units. Every request will be investigated to ensure that property is in compliance with relevant by-laws. Also, the fire department may request to conduct inspections periodically to ensure the fire safety elements of the buildings are maintained.

File a complaint

If you believe that an ADU/Accessory Apartment exists without receiving proper permits, approvals and inspections, you can file a by-law complaint.

File a by-law complaint