Backyard Home Zoning Rules in London, Ontario
London allows backyard homes as-of-right — no rezoning, no committee of adjustment — on most residential lots. Here are the actual rules, in plain English.
How many units
You can have up to 3 additional residential units per lot. Of those, a maximum of 2 units may be in one detached backyard building. Two separate backyard buildings are not permitted — one building, up to two units inside it.
Where it can go
The detached building must sit in the rear yard or interior side yard — not the front yard. Setbacks:
- Rear lot line: at least 3.0 m
- Interior side lot lines: at least 1.2 m, increasing to 3.0 m on any side where windows face the neighbouring lot
There is no maximum distance from the main house in the by-law. How far back the building can sit is set by your lot depth minus these setbacks.
How big it can be
- Height: 6.0 m maximum for the detached building
- Floor area: each unit cannot exceed 80% of the main house's gross floor area
- Bedrooms: maximum 2 per unit, with no more than 3 bedrooms combined in the building
- Lot coverage: the building counts toward your zone's maximum lot coverage (35% in R1-10, for example)
Servicing
The building must connect to municipal water and sanitary sewer. A lot on private septic does not qualify for a detached ARU as-of-right. We have asked City planning staff to confirm whether any variance or alternative path exists and will update this post with their answer.
Parking
No additional parking is required for the ARUs, and a new driveway for the backyard home is not permitted — it shares the existing driveway.
What this means on a real lot
Take a typical R1-10 lot, roughly 29 m wide by 76 m deep with a 52 m rear yard. After the 1.2 m side setbacks, you have about 26 m of buildable width; after the 3.0 m rear setback, deep placement is rarely the constraint. The binding limits are usually the 80%-of-house floor area cap and the 6.0 m height — which is why a bungalow lot can typically support a 1,600–2,100 sq ft single unit, well above standard 2-bedroom models.
The bottom line
If your London lot is residentially zoned, on municipal services, and has a workable rear yard, a detached backyard home with up to two units is permitted as-of-right. The details that decide feasibility are your lot dimensions, the main house's floor area, and servicing.
We check all of that in a free property review — zoning, setbacks, size caps, and servicing — before you commit to anything.
Last updated: September 30, 2026. Based on Zoning By-law Z.-1 as amended (OZ-9651/OZ-9661 and the March 2026 ARU amendment). Confirm current provisions with the City before designing or permitting.