Finishing the basement of an older Toronto house

The ceilingHeight decides the plan

The first thing we do in a Victorian semi or a 1950s bungalow is stand up straight and measure. The joists in a lot of central Toronto houses sit lower than a new build, and the ducts and beams underneath them lower again. The Ontario Building Code lets a basement second unit have a ceiling of 1.95 m over its required floor area, including the route to the exit, and that figure is the practical floor for any basement you want to use every day. Above it, we design around the beams and box in the ducts. Below it, the floor has to go down.

Two ways to do that. Underpinning digs beneath the existing footings in short sections and pours new concrete under them, so the whole basement floor drops and the walls stay flush. A bench footing pours a stepped concrete ledge inside the walls instead; it is faster and cheaper, and it costs you a bench of floor area along each wall. We draw both in 3D before you choose.

The permit drawings for either are prepared and stamped by a licensed structural engineer, and in Toronto the underpinning permit is priced per linear metre of wall. Read the full comparison on our bench footing versus underpinning page and the price detail on underpinning cost in Toronto.

The foundationRubble, block and water

Pre-war Toronto foundations are often rubble stone set in lime mortar, and the post-war ones concrete block. Both breathe. They let moisture through in a way a modern wall does not, and they shed mortar and parging when they are disturbed, which an underpinning crew will do.

We treat waterproofing as part of the finished basement, not a separate emergency. In an older house that means dealing with the walls before the studs go up: repointing where the mortar has gone, an interior membrane and drainage where water has shown up, a sump where the grade sends water toward the house. Then the framing goes in, wood studs with metal tracks held off the wall, insulated and vapour sealed, so the finished basement is dry because the wall behind it was dealt with, not because the drywall is hiding it. Our waterproofing guide walks through what each symptom usually means.

The wiringKnob and tube, sixty years on

Knob and tube wiring was used in houses from the early 1900s to the 1940s, and the Electrical Safety Authority notes that the current code is not retroactive, so plenty of it is still in service behind Toronto plaster. ESA's position is measured: the wiring can be safe when a Licensed Electrical Contractor has looked after it, and it lacks modern protections such as ground fault interrupters, and many insurers will not provide or renew coverage on a house that still has it. A finished basement changes the picture, because the new circuits for the pot lights, the bathroom and the bar have to connect to something.

Our electrical work is done by a Licensed Electrical Contractor, reported to ESA before it starts and inspected before the walls close, with the Certificate of Acceptance in your file. Where knob and tube runs through the basement ceiling, the quote shows the cost of replacing it as its own line, so you decide with the number in front of you rather than after the drywall is up.

The drainsClay pipe and the backwater valve

The sewer lateral under an older Toronto house is often vitrified clay laid in short sections, and the joints are where roots get in. A basement bathroom adds a fixture below grade, which is exactly where a surcharged city sewer pushes back during a storm. So the drains get looked at before the bathroom is placed in the 3D design, not after the tile is down.

The City requires a building permit to install a backwater valve and inspects it before it is covered, and it subsidizes the work. When a camera inspection shows a lateral that is failing, we tell you, and the repair or lining is priced as its own line. When it is sound, the bathroom goes where the plan wants it. Either way the basement bathroom is built once.