Garden suites & ADUs · Niagara (incl. Grimsby)
Garden Suites in Niagara & Grimsby
Niagara Region doesn't write zoning. Each of its 12 local municipalities (Grimsby, Lincoln, St. Catharines, Niagara Falls, Welland and the rest) has its own zoning by-law. This guide focuses on Grimsby, the Niagara town closest to our Ancaster base.
The rules, in plain language
What Niagara (incl. Grimsby) allows
In Grimsby, Zoning By-law 14-45 (November 2025 consolidation, Section 4.19) allows additional residential units with single detached, semi-detached and street townhouse dwellings, including one in a detached accessory building, which must follow the accessory building rules in Section 4.18. For anywhere else in Niagara, check that municipality's own by-law.
How many (Grimsby)
- Serviced residential and downtown lots (outside hamlets and the Niagara Escarpment Plan Area): up to 2 ARUs, either two in the house or one in the house and one detached.
- Hamlet Residential: 1 ARU. Rural and agricultural: 1, only in an existing building in the farm cluster.
- Escarpment lots follow the Niagara Escarpment Plan.
- Source: Grimsby Zoning By-law 14-45, Section 4.19, as of November 1, 2026
Other limits (Grimsby)
- A detached ARU must meet the accessory building rules in Section 4.18.
- No bed and breakfast, farm vacation or portable garden suite on a lot with an ARU.
- Water and sewage must meet Town and Region requirements.
- ARUs must stay subordinate to the main house.
- Source: Grimsby Zoning By-law 14-45, as of November 1, 2026
Check with the city: Grimsby applies its general accessory building standards for height, setbacks and coverage to detached ARUs. We haven't reproduced those numbers here, so confirm them with Grimsby Planning for your zone. For other Niagara municipalities, use that city or town's zoning by-law, since none of the Grimsby rules carry over. Fees and development charges (local and regional) aren't stated in these sources.
How we build it
Five ways to build in Niagara
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 Niagara's zoning for your lot. We check that before you commit.
Common questions
Niagara garden suite FAQ
Which by-law applies in Niagara?
The local municipality's. Niagara Region doesn't zone land. In Grimsby it's Zoning By-law 14-45.
Can I build a backyard unit in Grimsby?
Yes, on serviced residential and downtown lots: one detached ARU plus one in the house.
What about the escarpment?
ARUs in the Niagara Escarpment Plan Area follow the Escarpment Plan.
Sources
Official city sources
- Grimsby Zoning By-law 14-45 (Nov 2025 consolidation) (as of November 1, 2026)
- Town of Grimsby: Additional Residential Units (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.