Does underpinning need an engineer in Toronto?

Yes, in the cases that matter. A Professional Engineer has to design the underpinning where the new foundation goes below an adjacent building's footings within the soil's angle of repose, and professional review is mandatory where the unsupported underpinning height exceeds 1200 mm. Both conditions are normal on a Toronto semi or a narrow-lot detached house.

Underpinning also needs a building permit. The City's 2026 fee is $12.37 per linear metre against the $214.79 minimum permit fee.