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Rafters Sizes, High Slope (Over 3 in 12) With No Finished Ceiling - 20 psf Live Load, 7 psf Dead Load - 16" spacing

Calculating the size of the rafters you need when building a home or an addition is not a complex situation as we have provided a group of tables that will allow you to make your selection.

Note: Always check with your local building department to ensure that your choice of rafter sizes and material meets their requirements.

Four tables are provided:

  1. High Slope (Over 3 in 12) With No Finished Ceiling - 20 psf Live Load, 7 psf Dead Load - 12 inch spacing
  2. High Slope (Over 3 in 12) With No Finished Ceiling - 20 psf Live Load, 7 psf Dead Load - 16 inch spacing
  1. Low Slope (Over 3 in 12 or less) With No Finished Ceiling - 30 psf Live Load, - 12 inch spacing
  2. Low Slope (Over 3 in 12 or less) With No Finished Ceiling - 30 psf Live Load, - 16 inch spacing
High Slope (Over 3 in 12) With No Finished Ceiling
20 psf Live Load, 7 psf Dead Load - 16" spacing

Species

Grade

2 X 4

2 X 6

2 X 8

2 X 10

Coast Sitka Spruce

Select structural

10' 0"

15' 7"

20' 6"

26' 2"

No. 1 & Appearance

9' 9"

14' 2"

18' 9"

23' 11"

No. 2

8' 10"

13' 0"

17' 2"

21' 11"

No. 3

6' 8"

9' 10"

12' 11"

16' 6"

Douglas Fir, Larch
(North)

Select structural
or No. 1 & Appearance

10' 3"

16' 1"

21' 2"

27' 1"

No. 2

10' 0"

15' 4"

20' 2"

25' 9"

No. 3

7' 9"

11' 9"

15' 5"

19' 8"

Eastern Hemlock-
Tamarack (North)

Select structural
or No. 1 & Appearance

9' 2"

14' 5"

19' 0"

24' 3"

No. 2

8' 8"

13' 8"

18' 0"

22' 11"

No. 3

7' 3"

10' 9"

14' 3"

18' 2"

Hem-Fir (North)

Select structural

9' 8"

15' 2"

19' 11"

25' 5"

No. 1 & Appearance

9' 8"

15' 0"

19' 10"

25' 3"

No. 2

9' 3"

13' 7"

17' 11"

22' 10"

No. 3

6' 10"

10' 5"

13' 9"

17' 7"

Ponderosa Pine

Select structural

8' 11"

14' 1"

18' 6"

23' 8"

No. 1 & Appearance

8' 11"

13' 11"

18' 4"

23' 6"

No. 2

8' 8"

12' 6"

16' 6"

21' 1"

No. 3

6' 5"

9' 7"

12' 8"

16' 2"

Red Pine

Select structural

9' 2"

14' 5"

19' 0"

24' 3"

No. 1 & Appearance

9' 2"

13' 7"

17' 11"

22' 10"

No. 2

8' 6"

12' 4"

16' 3"

20' 9"

No. 3

6' 5"

9' 5"

12' 5"

15' 10"

Spruce Pine Fir

Select structural

9' 8"

15' 2"

19' 11"

25' 5"

No. 1 & Appearance

9' 7"

13' 11"

18' 4"

23' 5"

No. 2

8' 8"

12' 8"

16' 9"

21' 4"

No. 3

6' 6"

9' 7"

12' 8"

16' 2"

Western Cedars
(North)

Select structural
or No. 1 & Appearance

8' 8"

13' 8"

18' 0"

22' 11"

No. 2

8' 5"

12' 8"

16' 9"

21' 4"

No. 3

6' 6"

9' 10"

12' 11"

16' 6"

Western White Pine

Select structural

9' 5"

14' 6"

19' 1"

24' 5"

No. 1 & Appearance

9' 3"

13' 7"

17' 11"

22' 10"

No. 2

8' 3"

12' 2"

16' 1"

20' 6"

No. 3

6' 3"

9' 5"

12' 5"

15' 10"