Garage Conversions in Mississauga - Design, Permits, Construction

Mississauga's ARU by-law caps accessory structures at 10% rear-yard coverage, which on a typical Erin Mills lot works out to roughly 645 sq ft - enough for a two-bedroom garden suite but not for the three-bedroom units clients often ask about first. We size the concept to that percentage before drawing anything. Mississauga permits additional residential units under its 2022 ARU by-law - up to two units in the main dwelling plus one in an accessory structure, subject to a maximum 10% rear-yard coverage.

Large 1970s-90s subdivision lots with attached garages; garage conversions and rear coach houses are both common outcomes.

A garage was never built to be lived in: the slab sits above frost, the walls are usually uninsulated single-wythe, and the header over the vehicle door carries nothing. Every Mississauga conversion therefore starts with a structural and thermal assessment of what is already standing. The slab is the decisive item - an existing garage slab rarely bears on a 1.2 m footing, so we either underpin the perimeter or pour a new insulated slab inside the existing walls before any framing begins.

Converting the garage removes a parking space, which is why the 58/100 walkability of Mississauga matters more on this form than on any other - it decides whether parking relief is arguable or the driveway has to absorb the loss.