Garden suites & ADUs · Mississauga
Garden Suites in Mississauga
Mississauga calls a garden suite a detached additional residential unit (ARU). One is allowed per lot, as one or two storeys depending on the lot size. The city also has pre-approved plans for studio and one-bedroom garden suites.
The rules, in plain language
What Mississauga allows
Mississauga's Zoning By-law 0225-2007 (Table 4.1.1.14, added by By-law 0174-2023) sets the size and height of a detached ARU by lot size. Townhouse lots in the RM5 and RM6 zones can only have a garden suite on a corner or through lot, and standard condominium townhouses can't have one.
Size and storeys
- One storey on lots of 750 m² or less. Two storeys are possible on lots over 750 m².
- Floor area: 55 m² on lots of 550 m² or less. On larger lots, 10% of the lot area up to the cap in Table 4.1.1.14.
- It can't be taller than the main house or cover more of the lot than the main house does.
- Source: By-law 0174-2023, as of November 1, 2026
Height
- Sloped roof: 4.6 m for one storey, 6.8 m for two storeys.
- Flat roof: 3.0 m for one storey, 5.8 m for two storeys.
- Source: By-law 0174-2023, as of November 1, 2026
Setbacks
- Interior side: 0.6 m for one storey, 1.8 m for two storeys.
- Rear: 1.8 m.
- Exterior side (corner lots): 2.5 m for one storey, 4.5 m for two storeys.
- Source: By-law 0174-2023, as of November 1, 2026
Access and servicing
- A hard-surfaced fire access path at least 1.2 m wide and 2.1 m high, no longer than 45 m from the street to the door.
- Water and wastewater can be shared with the main house, or separate connections can be made through the Region of Peel.
- Window size and position are limited by distance to lot lines.
- Source: City of Mississauga: ARUs, as of November 1, 2026
Permits, fees and charges
- A building permit is required. Pre-approved plans still need a site plan and a grading plan.
- The city lists an $81.90 + HST fee for the garden suite's new municipal address, plus building permit fees.
- The city says development charges apply to garden suites.
- Heritage properties have extra restrictions.
- Source: City of Mississauga: ARUs, as of November 1, 2026
Check with the city: the maximum floor area for lots over 550 m² is "10% of the lot area, up to a maximum". The by-law copy we read is garbled at that number, so confirm the cap in the current Table 4.1.1.14. We also didn't confirm parking requirements or development charge amounts. Use Mississauga's property information tool for your lot.
How we build it
Five ways to build in Mississauga
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 Mississauga's zoning for your lot. We check that before you commit.
Common questions
Mississauga garden suite FAQ
How big can a garden suite be in Mississauga?
55 m² on lots of 550 m² or less. On larger lots, 10% of the lot area up to the by-law cap, and two storeys only on lots over 750 m².
How tall?
4.6 m (one storey) or 6.8 m (two storeys) with a sloped roof. 3.0 m or 5.8 m with a flat roof.
Are there development charges?
The city says development charges apply to garden suites.
Does Mississauga have pre-approved plans?
Yes, for studio and one-bedroom garden suites.
Sources
Official city sources
- City of Mississauga: Additional residential units (as of November 1, 2026)
- Mississauga By-law 0174-2023 (amending Zoning By-law 0225-2007) (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.