Sunken garage floor in Riverside South: who do I call?

A sunken garage floor slab is a concrete job, so start with a concrete contractor who works on garage slabs in the Ottawa area.

Before you call anyone, a few things are worth knowing so you can have a useful conversation.

Since March 1, 2026 the City of Ottawa has required a hardscaping contractor licence for businesses that install or alter hard landscaping features on private property, such as concrete pads, steps, walkways and patios. We found no City statement that it covers a floor inside a garage, so ask the City or the contractor whether it applies to your job. Ottawa Concrete Pros does not verify anyone's licence or insurance.

On the technical side, the 2024 Ontario Building Code sets the minimum concrete strength for a garage floor at 32 MPa after 28 days, and a maximum water-to-cementing-materials ratio of 0.45. The Code also says a garage floor shall be sloped to drain liquids to the outdoors, and that a construction joint shall be provided between a main building slab and a slab serving an attached garage. The minimum thickness for a floor-on-ground is 75 mm exclusive of any topping. We found no City statement on whether replacing an existing garage floor slab requires a building permit; ask the City's Building Code Services before the old floor comes out, because the City lists structural repairs and alterations among projects that do require a permit.

If any digging is involved, the Ontario Underground Infrastructure Notification System Act, 2012 requires a locate request through Ontario Dig Authority before any ground is broken. Locates are free and must be submitted at least five business days before digging starts.

We found too few published prices for a garage floor replacement to give a reliable range, so ask each contractor to itemize the quote: base preparation, removal and disposal of the old slab, concrete strength and mix, thickness, drainage slope, and any cold-weather protection if the air could be below 5 °C. The City's Trail Waste Facility takes clean concrete without rebar at $144 per tonne above 250 kg; ask whether disposal is in the quote.

Before work starts, make sure you have a written contract with the full scope and price, and the City's answer on any permit.