Floor Concrete Topping – Joist spans

(1)  Except as permitted in Sentence (2), where a floor is required to support a concrete topping, the joist spans shown in Table A-1 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 Table A-2 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 beam spans shown in Tables A-8 to A-11 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.

Article 9.23.4.4. Ontario Regulation 332/12 Building Code,   Information published by oncodes.ca for educational purposes only.