Prefab ADU 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 prefabricated unit shifts the build off your Mississauga lot and into a factory, which trades weather risk for access risk: the module still has to arrive on a truck and be craned over the house or in from the side yard. The site scope narrows to the foundation and the hookups - a 1.2 m frost footing or a screw-pile array, service trenching, then a one-day set - so the April-November window constrains far less of the schedule. Modules are CSA A277 certified in plant, so the Peel Region inspector reviews the foundation, the connections and the set rather than re-inspecting the framing and insulation.