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Table 29 (continued) Maximum spans for roof joists – 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)
Joist Spacing, mm (in.)
Joist Spacing, mm (in.)
Joist Spacing, mm (in.)
Joist Size, mm
300
400
600
300
400
600
300
400
600
Grade
in.
12
16
24
12
16
24
12
16
24
No. 1 and No. 2
38 x 89
2.47
2.24
1.96
2.16
1.96
1.71
1.96
1.78
1.56
2x4
8–1
7–4
6–5
7–1
6–5
5–7
6–5
5–10
5–1
38 x 140
3.89
3.53
3.08
3.40
3.08
2.69
3.08
2.80
2.45
2x6
12–9
11–7
10–1
11–2
10–1
8–10
10–1
9–2
8–0
38 x 184
5.11
4.64
4.05
4.46
4.05
3.54
4.05
3.68
3.22
2x8
16–9
15–3
13–4
14–8
13–4
11–7
13–4
12–1
10–7
38 x 35
6.52
5.93
5.18
5.70
5.18
4.52
5.18
4.70
4.11
2 x 10
21–5
19–5
17–0
18–8
17–0
14–10 17–0
15–5
13–6
38 x 286
7.94
7.21
6.30
6.94
6.30
5.50
6.30
5.73
5.00
2 x 12
26–1
23–8
20–8
22–9
20–8
18–1
20–8
18–9
16–5
38 x 89
2.23
2.03
1.77
1.95
1.77
1.55
1.77
1.61
1.41
2x4
7–4
6–8
5–10
6–5
5–10
5–1
5–10
5–3
4–7
38 x 140
3.51
3.19
2.79
3.07
2.79
2.43
2.79
2.53
2.21
2x6
11–6
10–6
9–2
10–1
9–2
8–0
9–2
8–4
7–3
38 x 184
4.61
4.19
3.66
4.03
3.66
3.20
3.66
3.33
2.91
2x8
15–2
13–9
12–0
13–3
12–0
10–6
12–0
10–11 9–6
38 x 235
5.89
5.35
4.68
5.15
4.68
4.09
4.68
4.25
2 x 10
19–4
17–7
15–4
16–11 15–4
13–5
15–4
13–11 12–1
38 x 286
7.17
6.52
5.58
6.26
5.69
4.80
5.69
5.17
4.27
2 x 12
23–6
21–5
18–4
20–7
18–8
15–9
18–8
17–0
14–0
No. 1 and No. 2
3.68
Note to Table 29 1. To determine the specified snow load in your location, contact your municipal building department.