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Table 31 (continued) Maximum spans for roof rafters – specified roof snow loads 1.0 to 2.0 kPa (20.9 to 41.8 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)
1.0 (20.9)
1.5 (31.3)
2.0 (41.8)
Rafter Spacing, mm (in.)
Rafter Spacing, mm (in.)
Rafter Spacing, mm (in.)
Rafter Size, mm
300
400
600
300
400
600
300
400
600
in.
12
16
24
12
16
24
12
16
24
No. 1 38 x 89 and No. 2 2 x 4
3.11
2.83
2.47
2.72
2.47
2.16
2.47
2.24
1.96
10–3
9–3
8–1
8–11
8–1
7–1
8–1
7–4
6–5
38 x 140
4.90
4.45
3.89
4.28
3.89
3.40
3.89
3.53
3.08
2x6
16–1
14–7
12–9
14–0
12–9
11–2
12–9
11–7
10–1
38 x 184
6.44
5.85
5.11
5.62
5.11
4.41
5.11
4.64
3.89
2x8
21–1
19–2
16–9
18–5
16–9
14–6
16–9
15–3
12–9
38 x 235
8.22
7.47
6.38
7.18
6.52
5.39
6.52
5.82
4.75
2 x 10
27–0
24–6
20–11 23–7
21–5
17–8
21–5
19–1
15–7
38 x 286
10.00
9.06
7.40
8.74
7.66
6.25
7.80
6.76
5.52
2 x 12
32–10 29–9
24–3
28–8
25–2
20–6
25–7
22–2
18–1
No. 1 38 x 89 and No. 2 2 x 4
2.81
2.55
2.23
2.46
2.23
1.95
2.23
2.03
1.77
9–3
8–5
7–4
8–1
7–4
6–5
7–4
6–8
5–10
38 x 140
4.42
4.02
3.44
3.86
3.51
2.91
3.51
3.14
2.56
2x6
14–6
13–2
11–3
12–8
11–6
9–6
11–6
10–4
8–5
38 x 184
5.81
5.13
4.19
5.00
4.33
3.54
4.41
3.82
3.12
2x8
19–1
16–10 13–9
16–5
14–3
11–7
14–6
12–6
10–3
38 x 235
7.24
6.27
5.12
6.12
5.30
4.33
5.40
4.67
3.82
2 x 10
23–9
20–7
16–10 20–1
17–5
14–2
17–8
15–4
12–6
38 x 286
8.40
7.27
5.94
7.10
6.15
5.02
6.26
5.42
4.43
2 x 12
27–7
23–10 19–6
23–3
20–2
16–6
20–6
17–9
14–6
Grade
Note to Table 31 1. To determine the specified snow load in your location, contact your municipal building department.