MODULAR X
MODULAR X

Hamilton

Garden suites in Hamilton. The City calls it a detached ADU.

Modular X designs, permits and builds detached additional dwelling units in Hamilton, the backyard homes most people call garden suites. Hamilton has permitted ADUs since its May 2021 zoning amendments, and a dedicated ADU team reviews permits for existing single-family houses with up to two internal units and one detached unit.

There is no instant zone-code lookup for Hamilton on our site. Start with feasibility. The City's Interactive Zoning Mapping shows which zoning by-law applies to an address.

Check if this lot qualifies →

Key takeaways

QuestionShort answerSource
What does Hamilton call it, and where can it go?A detached additional dwelling unit (ADU), in the rear or interior side yard.City of Hamilton - ADU
How is it serviced?Through the principal dwelling only; separate servicing to the street is not permitted.City of Hamilton - ADU
What fire access is required?An unobstructed 1.0 m wide path with 2.1 m vertical clearance from the street; City laneways do not count.City of Hamilton - ADU
What sets the size limits?The zoning by-law for the lot sets setbacks, height and floor areas; confirm them on the survey.City of Hamilton - ADU
Is a building permit required?Yes. Apply through my.hamilton.ca with vector PDF drawings; the permit fee must be paid before the application is accepted.City of Hamilton - ADU
How are costs approached?Pricing follows feasibility; parkland and development charges are set during permit review.City of Hamilton - ADU

Updated October 13, 2026.

ADU Hamilton: what the City means by a detached ADU

Hamilton defines an additional dwelling unit as a separate, self-contained unit on the property of a principal dwelling. It can be inside the house, added to it, or detached from it. Hamilton's zoning documents also call it a secondary dwelling unit. The detached version, a D-ADU in the City's shorthand, is the garden suite: a new building in the rear or interior side yard, or an existing accessory building such as a detached garage converted into a home.

A lot can hold more than one ADU. The City's own example is a detached garage converted into a unit plus a second unit on the upper floor of the house.

The Hamilton rules that shape the design

  • Location: rear yard or interior side yard. The City publishes layout diagrams for interior lots and corner lots.
  • Size: setbacks, height, ground floor area and gross floor area come from the zoning by-law that applies to the lot, and can depend on the size of the existing house. We confirm them on the survey and do not quote one city-wide number.
  • Servicing: through the principal dwelling only. Separate servicing to the street is not permitted. A water pipe sizing form is required, and the service may need an upgrade for the added fixtures.
  • Fire access: an unobstructed path at least 1.0 m wide with 2.1 m of vertical clearance from the street to the unit's entrance. City laneways do not count.
  • Parking: the City says up to three units are exempt from additional parking under the amended by-laws.
  • Grading: some detached ADUs need a professional grading design under Hamilton's residential infill rules, plus the Good Neighbour Guide notice.
  • Other approvals: heritage designation, conservation authority lands (Hamilton, Halton, Grand River or Niagara Peninsula) and the Niagara Escarpment Commission can each add a permit.

If a design does not fit the zoning by-law, a minor variance application is the City's route. Ontario's O. Reg. 462/24 also sets province-wide standards for these units, and we check the lot against both.

Permits in Hamilton, step by step

  1. Feasibility and survey: zoning, servicing route, fire path, trees and grading
  2. Design to the zoning by-law and the Ontario Building Code
  3. Grading design and Good Neighbour notice, where the City requires them
  4. Online application through the City's my.hamilton.ca customer portal, with drawings as vector PDFs. The application is not accepted until the permit fee is paid
  5. Tarion registration, which the City says applies to new detached ADUs
  6. A municipal address for the new unit, under the City's Municipal Addressing By-law
  7. Inspections through to occupancy

Hamilton requires every contractor to hold a valid Trade and Contractor Licence. We run the file, and you choose the plan and the finishes.

Hamilton ADU grant: closed to new applications

Hamilton's Additional Dwelling Unit and Multi-Plex Housing Incentive Program, funded through the federal Housing Accelerator Fund, was amended on 9 October 2025 to a grant covering a share of eligible costs per unit for sites in the Housing for Hamilton Community Improvement Project Area. The City now says the program has reached its funding capacity and the portal is closed to new submissions. We do not build a budget around it.

Modular and prefab homes in Hamilton

A factory-built (modular) detached ADU in Hamilton follows the same zoning, servicing and permit rules as a site-built one. It must qualify under the zoning by-law for the lot, connect services through the principal dwelling, and have an unobstructed fire path at least 1.0 m wide with 2.1 m of vertical clearance from the street to the entrance.

Ontario says modular homes must meet the Ontario Building Code. Buyers should confirm that the factory builds to code and that local permits are in place. We check the crane pick before you pay for a module.

Two ways to build

Full custom, foundation-up on your lot. Typical 9–14 months. Best for irregular lots and a house you want the suite to match.

Modular crane-in: we pour the slab and run the services from the house while the unit is built on a factory floor. Typical 5–8 months, when the lot allows the crane pick. We tell you if the pick does not work before you pay for a module. See modular vs site-built.

What it costs

Hamilton publishes no cost data, and we do not invent a Hamilton price. The City says an ADU may be subject to parkland and development charges, set during permit review. For the public figures that do exist in Ontario, see garden suite cost in Ontario. We price your lot after feasibility.

Related: what a garden suite is · garden suites in Burlington · garden suites in Oakville · GTA garden suite rules compared · garden suite plans · lot check · Home

FAQ

Yes. Hamilton amended its zoning by-laws in May 2021 to permit additional dwelling units. A detached ADU, which most people call a garden suite, can sit in the rear yard or the interior side yard, either newly built or converted from an existing accessory building. Eligibility is lot-specific, so the zoning for the address is checked first.

Sources

Municipal rules, fees, and programs change. Confirm current requirements with the city at application. Modular X provides exact pricing only after a site-specific feasibility review.