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Table 31 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 Douglas fir – larch (includes Douglas fir and western larch)
Hem – fir (includes western hemlock and amabilis fir)
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
Grade
in.
12
16
24
12
16
24
12
16
24
No. 1 and No. 2
38 x 89
3.27
2.97
2.59
2.86
2.59
2.27
2.59
2.36
2.06
2x4
10–9
9–9
8–6
9–4
8–6
7–5
8–6
7–9
6–9
38 x 140
5.14
4.67
3.95
4.49
4.08
3.34
4.08
3.60
2.94
2x6
16–10 15–4
12–11 14–9
13–5
10–11 13–5
11–10 9–8
38 x 184
6.76
5.88
4.80
5.74
4.97
4.06
5.06
4.38
3.58
2x8
22–2
19–4
15–9
18–10 16–4
13–4
16–7
14–5
11–9
38 x 235
8.30
7.19
5.87
7.02
6.08
4.96
6.19
5.36
4.38
2 x 10
27–3
23–7
19–3
23–0
19–11 16–3
20–4
17–7
14–4
38 x 286
9.63
8.34
6.81
8.14
7.05
5.76
7.18
6.22
5.08
2 x 12
31–7
27–5
22–4
26–9
23–2
18–11 23–7
20–5
16–8
38 x 89
3.27
2.97
2.59
2.86
2.59
2.27
2.59
2.36
2.06
2x4
10–9
9–9
8–6
9–4
8–6
7–5
8–6
7–9
6–9
38 x 140
5.14
4.67
4.08
4.49
4.08
3.50
4.08
3.71
3.08
2x6
16–10 15–4
13–5
14–9
13–5
11–6
13–5
12–2
10–1
38 x 184
6.76
6.14
5.04
5.90
5.21
4.26
5.31
4.60
3.75
2x8
22–2
20–2
16–6
19–4
17–1
14–0
17–5
15–1
12–4
38 x 235
8.63
7.54
6.16
7.36
6.37
5.20
6.49
5.62
4.59
2 x 10
28–4
24–9
20–2
24–2
20–11 17–1
21–4
18–5
15–1
38 x 286
10.11
8.75
7.15
8.54
7.40
6.04
7.53
6.52
5.33
2 x 12
33–2
28–9
23–5
28–0
24–3
19–10 24–9
21–5
17–6
No. 1 and No. 2
Continued on p. 300