Additional dwelling unit permits in Hamilton: forms, plans and fee

Check whether you need a permit

Adding additional dwelling units (ADU Internal), including municipal addressing and street naming, needs a building permit.
Additional dwelling units detached (ADU Detached), including municipal addressing and street naming, need a building permit.
In May 2021, amendments were made to the City's Zoning By-laws to permit Additional Dwelling Units (ADUs) in Hamilton.
We have a dedicated Additional Dwelling Unit Team to review and issue ADU building permits for existing single family dwellings including up to two internal units & one detached unit.
Building Engineering will continue to review multi-residential permits.
An Additional Dwelling Unit (ADU) is type of residential unit. It is a separate self-contained unit located on the property of a principal (main) dwelling. The unit may be created within, added to, or detached from the principal dwelling.
It is also referred to as a Secondary Dwelling Unit (SDU) within Zoning By-law documents.
An internal Additional Dwelling Unit (ADU) is a conversion of interior space within an existing dwelling or through a new addition to an existing dwelling to provide one (1) additional dwelling unit to a maximum of four (4) dwelling units in some zones. A new detached dwelling can also be purpose-built to include an internal additional dwelling unit.
A detached Additional Dwelling Unit (ADU) is a self-contained dwelling unit that is separate from the main dwelling on a lot. It may be newly constructed or created by converting an existing accessory building.
Example 4: A single detached dwelling with two (2) new additional dwelling units for a total of three (3) dwelling units. This is multi-residential and will be reviewed by Building Engineering staff.
Example 5: A two family dwelling with two (2) new additional dwelling units for a total of four (4) dwelling units. This is multi-residential and will be reviewed by Building Engineering staff.

How do I know if a property is eligible for an Additional Dwelling Unit?

To determine if a property is eligible for an Additional Dwelling Unit, look up the address using the Interactive Zoning Mapping. Refer to the appropriate section of the current Zoning By-Law for Secondary/Additional Dwelling unit regulations.
Note: There may be additional information such as site specific information, Conservation Authority, Heritage, Ministry of Transportation or other approvals required for a property. Contact the Zoning Section for further information.
A Detached ADU can be located in the rear yard or interior side yard of a property. Refer to the Zoning By-law for the full set of regulations that apply to Detached ADUs.
Note: All lots may not be able to accommodate a Detached ADU due to Ontario Building Code and Zoning By-Law requirements. Refer to the Secondary Dwelling Unit By-Law for the complete requirements of Detached - Additional Dwelling Units.
A detached ADU is permitted within some rural zones of the City of Hamilton Zoning By-laws. Please contact the Zoning Section for further information.
As per amended Secondary Dwelling Unit By-Laws, additional parking spaces for up to 3 units are now exempt from providing additional parking spaces. Additional review is required to determine compliance for newer buildings and the relative date of the passing of the by-law.
If the proposed ADU design does not conform to the Zoning By-law then an application can be made for a minor variance. If approved, a minor variance can grant permission for alternative provisions relating to the land, building or its use.
Note: Zoning inquiries related to multi-residential buildings containing three and four units can be directed to the Planning Division.
Zoning contact: call 905-546-2424 ext. 2719

Only if new construction in the ER zone of the former Ancaster Zoning By-law 87-57, or along the Hamilton Beach strip of the former Hamilton Zoning By-law 6593, including new Detached Secondary Dwelling Units

Zoning Compliance Review, if required

A Zoning Compliance Review under Applicable Law may be required in support of a building permit application for new construction of Single Detached Dwellings located in the ER zone of the former Ancaster Zoning By-law 87-57 or for new construction along the Hamilton Beach strip of the former Hamilton Zoning By-law 6593, including new Detached Secondary Dwelling Units.
Where required, a final conforming Zoning Compliance report is to be submitted at the time of building permit application.
For further information regarding the Zoning Compliance Review process, please call 905-546-2424 ext. 2719.

Only if the property is designated Heritage, or is on Conservation Authority or Niagara Escarpment Commission lands

Common Applicable Laws

Is the Property Designated Heritage? A Heritage Permit is required for properties designated Heritage, or properties located within the boundaries of a Heritage Conservation District. Check the City’s Cultural Heritage Resource Mapping to determine if the subject property is designated.
Is the Property on Conservation Authority or Niagara Escarpment Commission Lands? Development approval is required for lands within the conservation authorities. Visit the applicable conservation authority webpage below to determine if conservation approval is required.
Hamilton Conservation Authority 905-525-2181
Conservation Halton 905-336-1158
Grand River Conservation Authority 519-621-2761
Niagara Peninsula Conservation Authority 905-788-3135
Development approval is required for lands within NEC jurisdiction. Visit escarpment.org/planning/ to determine if the subject property is within the NEC. Contact the Niagara Escarpment Commission: 905-877-5191.

Check your water service

When proposing an Additional Dwelling Unit (ADU) additional plumbing fixtures will likely be added for a self-contained dwelling unit which includes a full kitchen, bathroom and laundry facility. Depending on the proposal the existing water service may not be adequate to service the total number of plumbing fixtures.
A water service upgrade to a larger pipe size and larger water meter may be required. Also, depending on the material of the existing water pipe (i.e. lead), a replacement may be required.
An ADU must have adequate servicing approved prior to issuance of the building permit.
The City of Hamilton only permits servicing connected through the principal dwelling.

Only if the house is served by a septic system

Septic Systems

Adding an additional dwelling unit to a house served by a septic system is permitted as long as the septic system has the capacity to handle the increase in sewage.
Otherwise, a separate building permit may be required to upgrade the system or install a separate septic system to serve the ADU.

Only if a professional grading plan is required for your secondary/additional detached dwelling unit

Detached ADU: add a professional grading plan, if required

To help mitigate impacts, the Building Division requires a professional grading design to be submitted for certain residential projects, including some additions and detached ADUs.

When is a Grading Plan Required?

These projects require a professional grading plan to be submitted (unless exempt below):

Secondary/additional detached dwelling unit

Grading Plan Exemptions

A professional grading plan is not required to be submitted for:

Residential project with a valid Site Alteration Permit related to the proposed scope of work.
Residential project subject to site plan approval wherein grading has been reviewed and approved by the Growth Management Division.

Additional Exemptions

A professional grading plan is not required to be submitted for these projects, provided there is no removal of, or alteration to, any existing development features (e.g. swales, catch basins, area drains, etc.), and no change to grades at the property line(s):

Residential accessory building and/or secondary/additional detached dwelling unit provided: it is not greater than 55 sq.m (≈ 592 sq ft). in building area and is at least 1.0 m (≈ 3 ft 3⅜ in) from property line(s); or where greater than 55 sq.m (≈ 592 sq ft). in building area, is at least 3.0 m (≈ 9 ft 10⅛ in) from property line(s).
Conversion of an existing detached accessory building to a secondary/additional dwelling unit.

Building Permit Application Requirements

These items are to be provided at the time of a building permit application:

the Building Division's Owner’s Undertaking Lot Grading Form, completed by both the property owner and the Grading Consultant;
the grading plan, sealed, signed, and dated by the Grading Consultant; and
the applicable grading security deposit.
A Grading Consultant shall be: An Ontario Land Surveyor; An Engineer registered as a member of the Professional Engineers of Ontario; An Architect registered as a member of the Ontario Association of Architects; or A member of the Ontario Association of Landscape Architects.
complete the Building Division's Lot Grading Certificate Declaration Form; and

Only if the construction of a detached secondary dwelling unit

Detached ADU: post a Residential Infill Information Notice

Refer to the Good Neighbour Guide for the information notice required for detached additional dwelling units and large additions.

How to Obtain an Information Notice

To obtain an Information Notice (Construction or Demolition), you must submit to the Building Division, in conjunction building permit submission to construct and/or demolish:

A completed Infill Information Notice Declaration Form
For new construction, electronic black and white renderings of the front and rear elevation of the building as it is expected to look following the completion of the project (JPEG format, minimum resolution of 300 dpi; no 3D renderings).
Renderings can be submitted to the plan reviewer via email.

Printing and Posting Information Notice

An electronic file containing a print-ready (PDF format) Information Notice will be provided to the applicant or owner. The applicant or owner is responsible – at their own cost – to print the Information Notice, in accordance with the specifications in By-law 21-207.
Minimum size: 0.61 m (≈ 2 ft) (24”) wide and 0.41 m (≈ 1 ft 4⅛ in) (16”) high
One (1) Information Notice is required for every lot line of the property that faces the street.
Construction: The Information Notice must be posted within (5) business days of the commencement of construction.
For construction, the Information Notice shall remain displayed until an Occupancy Permit has been issued.

Complete the forms4

Only if you are building a new Detached Additional Dwelling Unit (D-ADU)

New detached ADU: Tarion warranty details

New home construction warranty also applies to new Detached Additional Dwelling Units (D-ADUs).
Details are to be included in Section F of the application form.
If owner built, the owner details must be completed in Section E - Builder section.

Only if you have received a Fire Order for an illegal dwelling unit

If you have received a Fire Order

Apply for building permit in the normal manner with the Building Division.
With your application form include the Fire Order Number for reference in the description of work.
Submit a copy of the Fire Order and architectural drawings reviewed, approved and stamped by the Fire Department.

Apply for a municipal address

According to the newly in effect Municipal Addressing By-Law, it will be a requirement to apply for a municipal address and post the address/unit number(s).
To apply for a municipal address, visit Municipal Addressing. Additional fees apply.

Submit your application

Applications can now be submitted online by property owner, or agent acting on behalf of the owner.

Step 1: Create a City of Hamilton Account (my.hamilton.ca)
You will need to create an account at my.hamilton.ca/
Step 2: Access the Customer Portal
After signing in to my.hamilton.ca, select the Building Permits category to create your Customer Portal account.
Once you are setup on the Customer Portal, navigate to Getting Started and select Permitting & Inspections to apply, for a Building Permit and follow the steps.
Visit my.hamilton.ca/ and select the Building Permits category. Navigate to Getting Started and select Permitting & Inspections. Select an action and follow the steps.

Pay the fee

Additional dwelling unit in an existing house: $515 (Flat Fee)
Detached additional dwelling unit in the rear yard of a house: $1,030 (Flat Fee)
Building permit fees are payable online through the City’s application portal. A building permit application is not considered accepted until full payment has been received by the City of Hamilton.
An Additional Dwelling Unit may be subject to Parkland and Development charges.
All applicable fees are to be determined by the plan reviewer and Financial Team during permit application review.