Garden suites & ADUs · Milton
Garden Suites in Milton
Milton calls a backyard home an additional residential unit (ARU) in an accessory building. Under Milton's by-law, "garden suite" means a portable unit allowed only by a temporary use by-law, so a permanent backyard home is built as a detached ARU.
The rules, in plain language
What Milton allows
Milton's Comprehensive Zoning By-law 016-2014 (urban area, March 2026 consolidation) allows up to three additional dwelling units on detached, semi-detached, semi-link and townhouse lots, but only one of them in an accessory building. Lots need municipal water and wastewater service, and units aren't allowed on hazard lands or in the regulatory flood plain unless the conservation authority allows it.
Size
- Gross floor area up to the lesser of 10% of the lot area or 110 m².
- The building counts toward lot coverage.
- Source: By-law 016-2014, Section 4.2.5, as of November 1, 2026
Height
- Up to 3.5 m with a flat roof.
- Up to 4.3 m with a gable, hip, gambrel or mansard roof.
- No rooftop amenity areas. Decks at most 0.6 m above grade.
- Source: By-law 016-2014, Sections 4.2.5 and 4.3.1, as of November 1, 2026
Setbacks and separation
- Rear yard or interior side yard only.
- At least 1.2 m from the interior side lot line and 1.5 m from the rear lot line.
- At least 3.5 m from the main house, including any roofed structure attached to it.
- Exterior side: no closer than the main house is allowed to be.
- Source: By-law 016-2014, Section 4.2.5, as of November 1, 2026
Access and parking
- A clear path at least 1.2 m wide and 2.1 m high from the street to the entrance.
- The parking table lists 1 space per additional dwelling unit.
- Source: By-law 016-2014, Section 4.10 and parking table, as of November 1, 2026
Permits and registration
- A building permit is required (application, site plan, floor plans, construction and fire-separation details).
- Every ARU must be registered with the Town once it is built. Registration is a three-year pilot launched in 2025.
- Source: Town of Milton: Build an ARU, as of November 1, 2026
Check with the city: confirm the parking requirement for your lot, since provincial rules may limit what a municipality can require for additional units. Rural and Niagara Escarpment lots have separate rules, and detached ARUs aren't allowed in the Escarpment Rural Area. Development charges, permit fees and servicing details aren't stated on these pages, so check with Milton Building Services.
How we build it
Five ways to build in Milton
01
Geohaus factory-built
Perimeter Homes is a Geohaus partner. Studio, one- and two-bedroom layouts built in a factory and set on your lot.
See the Geohaus layouts02
Modular / prefab
Factory-built modular garden suites and backyard homes, with sizes adjustable to your lot and local rules.
Browse the model gallery03
Custom stick-built
Framed on site for tight, sloped or oddly shaped lots, or a layout no catalogue covers.
How custom worksEvery design still has to fit Milton's zoning for your lot. We check that before you commit.
Common questions
Milton garden suite FAQ
How big can a backyard unit be in Milton?
The lesser of 10% of the lot area or 110 m² gross floor area (By-law 016-2014, Section 4.2.5).
How tall?
3.5 m with a flat roof, 4.3 m with a pitched roof.
Do I have to register it?
Yes. Milton requires every ARU to be registered with the Town after construction.
Is a "garden suite" allowed in Milton?
In Milton's by-law a garden suite is a portable unit allowed only by a temporary use by-law. A permanent backyard home is a detached ARU.
Sources
Official city sources
- Milton Comprehensive Zoning By-law 016-2014 (March 2026) (as of November 1, 2026)
- Town of Milton: Build an ARU (as of November 1, 2026)
- Town of Milton: Learn about the ARU program (as of November 1, 2026)
This guide summarizes public city information and isn't planning or legal advice. Rules change. Confirm your lot with the city before you apply.
Start here
Talk to a garden suite builder.
Tell us about your lot and which option you're considering. We reply within one business day.