Most of the questions we get about ceiling height are really questions about a second unit. Here is how the process is put together in Mississauga, and the step almost everybody misses.
The City defines a second unit as a self-contained living space with its own cooking, sleeping and sanitary facilities, inside a detached house, a semi-detached house or a townhouse. In practice that is the basement apartment most people are describing.
Three separate sets of rules apply to it at once: the Ontario Building Code, the Ontario Fire Code, and the City's zoning by-law. They cover different things — construction and egress, fire separation and alarms, and what is permitted on your lot — and satisfying one of them does not satisfy the others.
Mississauga requires second units to be registered with the City, and keeps a public register of them. The registration itself is free. What it asks for is proof of ownership, a completed registration form, and a copy of the second unit building permit signed off by every City inspector involved — which means the registration only happens once the work is actually finished and passed.
An unregistered unit is not a legal one, even if it was built under a permit. That distinction turns up during insurance claims and during sales, which is a bad time to discover it.
The City of Mississauga's own page on registering a second unit sets out the current documents and process. Check it directly rather than relying on any contractor's summary, including ours.
The Building Code sets minimum heights for habitable space, and which figure applies depends on how your project is classified — new construction, or an existing house being converted. Your designer confirms that for your address. What is not in dispute is that a basement measuring six and a half feet to the underside of the joists is short before the ducts are even considered.
Bedrooms need a means of escape, which is either a window sized to climb out of or a door directly outside. On a lowered basement, both of those are easier and cheaper to build while the floor is open — see egress windows and walkouts.
The unit has to be separated from the rest of the house, and the assemblies and alarms that achieve that are specified on the drawings. The ceiling is part of that, and it costs height — which is another reason to settle the floor level before the drawings are finished, not after.
The furnace, water heater, panel and the buried drain all sit in the space you are converting. Where they end up decides the layout, and moving them is easiest while the floor is already out.
Slab to joist, in several places. Note the lowest duct and beam. That single number tells you whether this is a finishing project or a structural one.
Zoning first. There is no point designing a unit the by-law does not allow on your property.
The drawings determine the scope. A quote produced before them is a guess that will change.
Underpinning or benching, and which walls get which. This is a drawing decision, not a site decision.
The inspections are staged, and the sequence is tied to them.
Once every inspector has signed off. This is the step that makes the apartment legal.
We do the structural half: lowering the floor, the foundation work, the walkout, the windows and the drainage. We do not prepare the second-unit drawings, we do not register the unit for you, and we will not tell you your basement complies — that is the designer's and the City's call, and anyone who tells you otherwise on a first visit has not seen your drawings either.
It depends on whether your project is treated as new construction or as an existing building being converted, and the two are not the same number. Your designer confirms which applies to your house before drawings are submitted. What we can say without qualification is that a typical six-and-a-half-foot 1960s basement is under it, and that ducts and the fire-separated ceiling both come off the top of whatever you have.
Yes. Mississauga requires second units to be registered, and registration asks for the permit signed off by the inspectors as one of its documents. A permitted but unregistered unit is not a legal second unit.
The registration itself is free. The costs in this project are the design work, the building permit, the inspections and the construction.
You can, and it is often the sensible way to phase the money. Tell the designer that is the plan so that the floor level, the window openings and the service locations are set for a future unit rather than for a rec room. Retrofitting those decisions is where phased projects lose their savings.
Tell us the height you have, the height you want and what the room is for. That is usually enough for a clear recommendation before anybody measures anything.