Code Library › Volume 1 › Section 9.23 — Wood Frame Construction
PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code

9.23.4.4.Concrete Topping (See Note A-9.23.4.4.)

(1) Except as permitted in Sentence (2), where a floor is required to support a concrete topping, the joist spans shown Span Table 9.23.4.2.-A or the spacing of the members shall be reduced to allow for the loads due to the topping. (2) Where a floor is required to support a concrete topping, joist spans are permitted to be selected from Span Table 9.23.4.2.-B provided the concrete (a) is 38 to 51 mm thick, (b) is normal weight, (c) is placed directly on the subflooring, and (d) has not less than 20 MPa compressive strength after 28 days. (3) Where a floor is required to support a concrete topping not more than 51 mm thick, the allowable beam spans shown in Span Tables 9.23.4.2.-H to 9.23.4.2.-K shall be multiplied by 0.8 or the supported length of the floor joists shall be reduced to allow for the loads due to the topping.

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.