Garage additions and conversions cover two related but different jobs. An addition means building a new attached or detached garage where none exists, or extending an existing one, which involves a new foundation, framing tied into the house or built freestanding, roofing, and a driveway apron. A conversion means turning an existing garage into livable space (a rec room, home office, in-law suite, or gym) or, less often, turning a converted space back into a working garage to satisfy a resale requirement. We've reviewed 11 businesses in Mississauga that handle this kind of work.
Both jobs touch on structural, electrical, insulation, and permitting work that's easy to get wrong. A garage addition needs a proper footing below the frost line, correctly sized headers if you're cutting into an existing wall, and drainage that keeps water away from the house rather than toward it. A conversion needs insulation and vapor barrier upgrades (garages are rarely built to livable-space code), a subfloor solution if the slab is uneven or prone to damp, and often a change to the electrical panel if you're adding heat, lighting, or a bathroom. Mississauga's building department requires permits for both, and a contractor who suggests skipping that step is a red flag, not a shortcut.
When comparing contractors, look at whether they pull permits themselves, whether they give you a written scope with materials specified (not just a lump sum), and whether they've done the specific job you need (a conversion is not the same skill set as pouring a new slab). Our ranked guide to Mississauga's garage addition and conversion contractors scores companies on the criteria explained in our methodology, so you can compare them on more than star ratings alone.
