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Ironwood Builders Converting a garage to living space is fairly common, though my knowledge of Canada's codes is non-existent, it can't be so foreign they don't get asked. Contact your local building department and ask the question! Some info from the States...Many jurisdictions require covered off street parking, so if the garage is converted, there is a possibility that there will need to be a compensatory carport added. Your local building department will be able to confirm any requirements.

Mega Builders I'm not sure what the local codes are where you live.
Where we are (city of Los Angeles), garages can be converted into living spaces as long as alternative covered parking is provided. In other municipalities, this is not the case and a residence must have a garage.
If a conversion is legal in your city (a call to the city will answer this in short order), you'd need to make the space habitable. That means insulation, electrical, wall covering, means of emergency egress and so forth - all would need to comply with local codes for habitable space.
Good luck!

Ironwood Builders The Brampton Building Department can be accessed on the internet... http://www.brampton.ca/EN/residents/Building-Permits/Pages/welcome.aspx. You may have an easier time on the phone or in person, i don't know the area that well!

A Kitchen That Works LLC If you do find your local building department is amenable, consider insulating the existing slab (foundation) to make sure the room is comfortable. Many homeowners overlook this step and experience high heating costs and limited comfort in these converted spaces.

Gabriela D. Thanks to all for your answers! I will post what I find ;)

Norm Walters Construction Inc. There may be a problem with the elevation of the garage floor if converted to living space.