Partial replacement of a cracked slab in Stittsville: good idea?

Partial replacement can work, but the result depends heavily on what is causing the cracking and what condition the surrounding slab is in. Before committing to a patch, have a contractor assess whether the cracked section failed because of the base beneath it, frost movement, or something else, and ask how the repair addresses that cause.

The 2024 Ontario Building Code sets 32 MPa as the standard for exterior flatwork; we found no Code statement on whether that standard binds a patio slab built without a permit, but it is the right benchmark to ask for in writing regardless.

A few things the City of Ottawa's rules add to this job. The City's Hardscaping Contractor Licence, in effect since March 1, 2026, covers concrete pads, patios, walkways and steps on private property. The Licensing By-law also excludes "minor repairs or minor alterations", which it does not define, so ask the City whether your job counts. Ask any contractor to show you their City licence and check the City's published list yourself. Ottawa Concrete Pros does not verify anyone's licence or insurance. If the cracked section is near the front of the property and any work touches the right of way, the Access By-law 2026-139 applies: resurfacing an existing access does not require a permit, but altering its location or dimensions does. Whoever breaks ground must submit a locate request through Ontario Dig Authority at least five business days before digging; ask who will submit it.

On the quote itself, ask for these items to be written out separately:

• removal and disposal of the broken section (clean concrete without rebar goes to the City's Trail Waste Facility at $144 per tonne above 250 kg, $36 minimum)
• base inspection and any base work needed under the new section
• the concrete strength (32 MPa for exterior flatwork)
• cold-weather protection if the pour happens when the air temperature is below 5 °C, including how long the slab will be kept at not less than 10 °C
• whether a minimum charge applies, since Ottawa price pages note small jobs often hit a minimum of about $5,500

We found no published price range with enough sources to quote a figure for partial replacement on its own, so get it itemized rather than as a single number.

Ask the contractor to show you, in writing, exactly what base work is included and what it will cost if the base turns out to need more than the quote assumed.