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Table 30 (continued) Maximum spans for roof joists – specified roof snow loads 2.5 and 3.0 kPa (52.2 and 62.7 psf) Maximum Span, m (ft.–in.) Specified Snow Load, kPa (psf)1
Commercial Designation Spruce, pine, or fir (includes spruce [all species except coast sitka spruce], jack pine, lodgepole pine, balsam fir and alpine fir)
Northern species (includes any Canadian species covered by the NLGA Standard Grading Rules)
2.5 (52.2)
3.0 (62.7)
Joist Spacing, mm (in.)
Joist Spacing, mm (in.)
Joist Size, mm
300
400
600
300
400
600
Grade
in.
12
16
24
12
16
24
No. 1 and No. 2
38 x 89
1.82
1.65
1.44
1.71
1.56
1.36
2x4
6–0
5–5
4–9
5–7
5–1
4–6
38 x 140
2.86
2.60
2.27
2.69
2.45
2.14
2x6
9–5
8–6
7–5
8–10
8–0
7–0
38 x 184
3.76
3.42
2.99
3.54
3.22
2.81
2x8
12–4
11–3
9–10
11–7
10–7
9–3
38 x 235
4.81
4.37
3.82
4.52
4.11
3.59
2 x 10
15–9
14–4
12–6
14–10
13–6
11–9
38 x 286
5.85
5.31
4.64
5.50
5.00
4.37
2 x 12
19–2
17–5
15–3
18–1
16–5
14–4
38 x 89
1.64
1.49
1.31
1.55
1.41
1.23
2x4
5–5
4–11
4–3
5–1
4–7
4–0
38 x 140
2.59
2.35
2.05
2.43
2.21
1.93
2x6
8–6
7–9
6–9
8–0
7–3
6–4
38 x 184
3.40
3.09
2.70
3.20
2.91
2.53
2x8
11–2
10–2
8–10
10–6
9–6
8–4
38 x 235
4.34
3.94
3.35
4.09
3.71
3.10
2 x 10
14–3
12–11
11–0
13–5
12–2
10–2
38 x 286
5.28
4.76
3.89
4.97
4.40
3.59
2 x 12
17–4
15–7
12–9
16–4
14–5
11–9
No. 1 and No. 2
Note to Table 30 1. To determine the specified snow load in your location, contact your municipal building department.