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Table 16 (continued) Maximum spans for built-up floor beams supporting not more than two floors1, 2
Commercial Designation Northern Species
Grade No. 1 and No. 2
Supported Length, m5, 6 ft
Maximum Span, m (ft.­­–in.)3, 4 Size of Built-up Beam, mm (in.) 38 x 184 38 x 235 38 x 286 2x8 2 x 10 2 x 12 3-ply 4-ply 5-ply 3-ply 4-ply 5-ply 3-ply 4-ply 5-ply
2.4
1.94
2.24
2.50
2.37
2.73
3.06
2.75
3.17
3.55
8
6–4
7–3
8–2
7–8
8–11
9–11
8–11
10–4
11–6
3.0
1.73
2.00
2.24
2.12
2.44
2.73
2.46
2.84
3.17
10
5–8
6–6
7–3
6–11
7–11
8–11
8–0
9–3
10–4
3.6
1.58
1.83
2.04
1.93
2.23
2.50
2.24
2.59
2.90
12
5–2
5–11
6–8
6–3
7–3
8–1
7–4
8–5
9–5
4.2
1.46
1.69
1.89
1.79
2.07
2.31
2.08
2.40
2.68
14
4–9
5–6
6–2
5–10
6–9
7–6
6–9
7–10
8–9
4.8
1.37
1.58
1.77
1.67
1.93
2.16
1.94
2.24
2.51
16
4–5
5–2
5–9
5–5
6–3
7–0
6–4
7–4
8–2
5.4
1.29
1.49
1.67
1.58
1.82
2.04
1.83
2.11
2.36
18
4–2
4–10
5–5
5–2
5–11
6–8
6–0
6–11
7–8
6.0
1.22
1.41
1.58
1.50
1.73
1.93
1.74
2.01
2.24
20
4–0
4–7
5–2
4–10
5–8
6–3
5–8
6–6
7–4
Notes to Table 16 1. Spans apply only where the floors serve residential areas. 2. When the floors have a concrete topping of not more than 51 mm (2 in.), the spans must be multiplied by 0.8. 3. Spans are clear spans between supports. For total span, add two bearing lengths. 4. 3-ply beams with supported lengths greater than 4.2 m (13 ft.–8 in.) require 114 mm (41⁄2 in.) of bearing. All other beams require 76 mm (3 in.) bearing. 5. Supported length means half the sum of the joist spans on both sides of the beam. 6. Straight interpolation may be used for other supported lengths.