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Rafters Sizes, High Slope (Over 3 in 12) With No Finished Ceiling - 20 psf Live Load, 7 psf Dead Load - 12 inch 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
  3. Low Slope (Over 3 in 12 or less) With No Finished Ceiling - 30 psf Live Load, - 12 inch spacing
  4. 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 - 12" spacing

Species

Grade

2 X 4

2 X 6

2 X 8

2 X 10

Coast Sitka Spruce

Select structural

11' 1"

17' 4"

22' 11"

29' 2"

No. 1 & Appearance

11' 1"

16' 5"

21' 7"

27' 7"

No. 2

10' 3"

15' 0"

19' 10"

25' 3"

No. 3

7' 8"

11' 4"

15' 0"

19' 1"

Douglas Fir, Larch
(North)

Select structural
or No. 1 & Appearance

11' 3"

17' 8"

23' 4"

29' 9"

No. 2

11' 1"

17' 4"

22' 11"

29' 2"

No. 3

8' 11"

13' 6"

17' 10"

22' 9"

Eastern Hemlock-
Tamarack (North)

Select structural
or No. 1 & Appearance

10' 1"

15' 11"

20' 11"

26' 9"

No. 2

9' 7"

15' 0"

19' 10"

25' 3"

No. 3

8' 4"

12' 5"

16' 5"

20' 11"

Hem-Fir (North)

Select structural
or No. 1 & Appearance

10' 7"

16' 8"

22' 0"

28' 0"

No. 2

10' 4"

15' 8"

20' 8"

26' 5"

No. 3

7' 11"

12' 1"

15' 11"

20' 4"

Ponderosa Pine

Select structural
or No. 1 & Appearance

9' 10"

15' 6"

20' 5"

26' 0"

No. 2

9' 7"

14' 6"

19' 1"

24' 4"

No. 3

7' 5"

11' 1"

14' 8"

18' 8"

Red Pine

Select structural

10' 1"

15' 11"

20' 11"

26' 9"

No. 1 & Appearance

10' 1"

15' 8"

20' 8"

26' 5"

No. 2

9' 10"

14' 3"

18' 10"

24' 0"

No. 3

7' 5"

10' 10"

14' 4"

18' 3"

Spruce Pine Fir

Select structural

10' 7"

16' 8"

22' 0"

28' 0"

No. 1 & Appearance

10' 7"

16' 1"

21' 2"

27' 0"

No. 2

10' 0"

14' 8"

19' 4"

24' 8"

No. 3

7' 6"

11' 1"

14' 8"

18' 8"

Western Cedars
(North)

Select structural
or No. 1 & Appearance

9' 7"

15' 0"

19' 10"

25' 3"

No. 2

9' 3"

14' 7"

19' 2"

24' 6"

No. 3

7' 6"

11' 4"

15' 0"

19' 1"

Western White Pine

Select structural

10' 4"

16' 3"

21' 6"

27' 5"

No. 1 & Appearance

10' 4"

15' 8"

20' 8"

26' 5"

No. 2

9' 7"

14' 1"

18' 7"

23' 8"

No. 3

7' 3"

10' 10"

14' 4"

18' 3"