Start with London’s current suite guidance
London’s ARU page covers interior conversions, additions, garage conversions and detached units. The city warns that not every lot qualifies; setbacks, lot dimensions, coverage, parking and current zoning have to be checked before the permit application.
Open the official London suite source ↗The broader Southwestern Ontario housing pattern does not replace the London approval file. Confirm this address and unit type with the local source.
Ontario: the provincial layer
The Ontario ARU framework can support as many as three units in the principal house, or two principal-house units plus one ancillary-building unit, on identified lands. Municipal zoning still controls site details.
Ontario additional residential unit framework ↗Four questions before design
What kind of unit?
An internal conversion and a new detached unit can share a goal but not an approval path.
Is the use allowed?
Separate entitlement from construction. The city may allow another unit in principle while still regulating its size, location or form.
Can the building comply?
The code review is where an attractive floor plan meets life-safety requirements. Confirm exits, separations and building systems early.
Can the site serve it?
For backyard or garden units, test the site for setbacks, access, servicing and utility capacity before finalizing the footprint.
From London zoning to final inspection
Keep a single project file with zoning confirmation, plans, permits, inspection results and any occupancy or registration documents required locally.
If you are buying a property with an existing suite, ask for permit and inspection records instead of relying on a listing description or current tenant.
Official sources
Reviewed 2026-09-14. The local suite/ADU source and the provincial building layer were both checked here, but the final step is confirming the current parcel and permit requirements.