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Table 32 Maximum spans for roof rafters – 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 Douglas fir – larch (includes Douglas fir and western larch)
Hem – fir (includes western hemlock and amabilis fir)
2.5 (52.2)
3.0 (62.7)
Rafter Spacing, mm (in.)
Rafter Spacing, mm (in.)
Rafter Size, mm
300
400
600
300
400
600
Grade
in.
12
16
24
12
16
24
No. 1 and No. 2
38 x 89
2.41
2.19
1.86
2.27
2.06
1.71
2x4
7–11
7–2
6–1
7–5
6–9
5–7
38 x 140
3.76
3.26
2.66
3.46
3.00
2.45
2x6
12–4
10–8
8–9
11–4
9–10
8–0
38 x 184
4.58
3.96
3.24
4.21
3.65
2.98
2x8
15–0
13–0
10–7
13–10
12–0
9–9
38 x 235
5.60
4.85
3.96
5.15
4.46
3.64
2 x 10
18–4
15–11
13–0
16–11
14–8
11–11
38 x 286
6.50
5.63
4.59
5.98
5.17
4.23
2 x 12
21–4
18–5
15–1
19–7
17–0
13–10
38 x 89
2.41
2.19
1.91
2.27
2.06
1.80
2x4
7–11
7–2
6–3
7–5
6–9
5–11
38 x 140
3.79
3.42
2.79
3.57
3.14
2.57
2x6
12–5
11–3
9–2
11–8
10–4
8–5
38 x 184
4.80
4.16
3.40
4.42
3.83
3.12
2x8
15–9
13–8
11–2
14–6
12–7
10–3
38 x 235
5.87
5.08
4.15
5.40
4.68
3.82
2 x 10
19–3
16–8
13–7
17–9
15–4
12–6
38 x 286
6.81
5.90
4.82
6.27
5.43
4.43
2 x 12
22–4
19–4
15–10
20–7
17–10
14–6
No. 1 and No. 2
Continued on p. 302