1. Spans provided in this Subsection for joists, beams and lintels supporting floors shall apply only where
   1. the floors serve residential areas as described in Table 4.1.5.3., or
   2. the uniformly distributed live load on the floors does not exceed that specified for residential areas as described in Table 4.1.5.3.
2. Spans for joists, beams and lintels supporting floors shall be determined according to Subsection 4.1.3. where the supported floors
   1. serve other than residential areas, or
   2. support a uniform live load in excess of that specified for residential areas.

1. Except as required in Sentence (2) and Article 9.23.14.10., spans for wood joists and rafters shall conform to the spans shown in Span Tables 9.23.4.2.-A to 9.23.4.2.-G for the uniform live loads shown in the Tables. (See Article 9.4.2.2.)
2. Spans for floor joists that are not selected from Span Tables 9.23.4.2.-A and 9.23.4.2.-B and that are required to be designed for the same loading conditions, shall not exceed the design requirements for uniform loading and vibration criteria. (See Note A-9.23.4.2.(2).)
3. Spans for built-up wood and glued-laminated timber floor beams shall conform to the spans in Span Tables 9.23.4.2.-H to 9.23.4.2.-K. (See Article 9.4.2.2.)
4. Spans for roof ridge beams shall conform to the spans in Span Table 9.23.4.2.-L for the uniform snow load shown. (See Articles 9.4.2.2. and 9.23.14.8.)

1. The spans for steel floor beams with laterally supported top flanges shall conform to Table 9.23.4.3. (See Note A-9.23.4.3.(1).)
2. Beams described in Sentence (1) shall at least meet the requirements for Grade 350 W steel contained in CSA G40.21, "Structural Quality Steel."

Table 9.23.4.3.
Maximum Spans for Steel Beams Supporting Floors in Dwelling Units⁽¹⁾
Forming Part of Sentence 9.23.4.3.(1)

Notes to Table 9.23.4.3.:
(1) See Note A-Table 9.23.4.3.

1. Except as permitted in Sentence (2), where a floor is required to support a concrete topping, the joist spans shown in 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
   1. is 38 to 51 mm thick,
   2. is normal weight,
   3. is placed directly on the subflooring, and
   4. 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.

1. Where a roof is required to support an additional uniform dead load from roofing materials such as concrete roofing tile, or materials other than as specified in Section 9.27., such as clay roofing tiles, the additional load shall be allowed for by reducing
   1. the spans for roof joists and rafters in Span Tables 9.23.4.2.-D to 9.23.4.2.-G, or the spacing of the members, and
   2. the spans for ridge beams and lintels in Span Tables 9.23.4.2.-L and 9.23.12.3.-A to 9.23.12.3.-D.

      (See Note A-9.23.4.2.)