PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code
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9.3.1.7.Concrete Mixes (See Note A-9.3.1.7.)
(1) For pre-mixed concrete and for the site-batched concrete mixes described in Table 9.3.1.7., the maximum ratio of
water to cementing materials measured by weight shall not exceed
(a) 0.45 for garage floors, carport floors and all exterior flatwork,
(b) 0.65 for interior floors other than those for garages and carports, and
(c) 0.70 for all other applications.
(2) The size of aggregate in unreinforced site-batched concrete mixes referred to in Sentence (1) shall not exceed,
(a) 1/5 the distance between the sides of vertical forms, or
(b) 1/3 the thickness of flatwork.
Table 9.3.1.7.
Site-Batched Concrete Mixes
Forming Part of Sentence 9.3.1.7.(1)
Materials, volume
Maximum Size of Coarse Fine Aggregate Coarse Aggregate
Cementing Material
Aggregate, mm (damp average coarse sand) (gravel or crushed stone)
Parts(1) L Parts L Parts L
14 1 28 1.75 49 2 56
20 1 28 1.75 49 2.5 70
28 1 28 2 56 3 84
40 1 28 2 56 3.5 98
Notes to Table 9.3.1.7.:
(1) 1 part cementing material = 1 × 40 kg bag
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.