The Ontario Building Code | Cold Weather Requirements
220.127.116.11. Cold Weather Requirements
(1) When the air temperature is below 5°C , concrete shall be,
(a) kept at a temperature of not less than 10°C or more than 25°C while being mixed and placed, and
(b) maintained at a temperature of not less than 10°C for 72 h after placing.
(2) No frozen material or ice shall be used in concrete described in Sentence (1).
9.3.2. Lumber and wood Products