Should the Ottawa contract cover cold-weather protection?

Yes, the contract should address cold-weather protection whenever there is a real chance the air temperature will drop below 5 °C during or after the pour. The 2024 Ontario Building Code sets out what that protection must achieve.

Under section 9.3.1.9 of the Code, when the air temperature is below 5 °C, concrete must be kept at not less than 10 °C and not more than 25 °C while it is being mixed and placed, and then maintained at not less than 10 °C for 72 hours after placing. No frozen material or ice may be used in the mix. Those are the Code's requirements; the contract should say how the contractor plans to meet them, not just that they will.

What that means in practice is that the written contract or specification should spell out at least these points:

• the temperature trigger the contractor uses to decide whether protection is needed
• what method will be used to maintain the required temperature range during and after the pour
• how long the protection will stay in place (at minimum, the 72-hour Code period)
• who monitors the temperature and what happens if conditions change overnight

The National Research Council's Canadian Building Digest 116 notes that freezing concrete in the plastic state usually results in permanent damage, even with a single freeze-thaw cycle. Have the contract confirm the 72-hour period explicitly.

If there is any chance of a pour with the air below 5 °C, ask the contractor to add a cold-weather clause before you sign.

The City's Hardscaping Contractor Licence, required since March 1, 2026 for businesses installing concrete patios, walkways, steps and pads on private property, requires contractors to provide written contracts. We did not find what the licence requires those contracts to contain, so ask for the cold-weather detail yourself.

Ask the contractor directly what their written cold-weather plan is and how it is documented, because that is the clearest way to know whether the 72-hour Code requirement will actually be met on your job.