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Rafters Sizes, Low Slope (Over 3 in 12 or less) With No Finished Ceiling - 30 psf Live 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
Low Slope (Over 3 in 12 or less) With No Finished Ceiling 30 psf Live Load, - 12" spacing

Species

Grade

2 X 6

2 X 8

2 X 10

2 X 12

Coast Sitka Spruce

Select structural

13' 9"

18' 2"

23' 2"

28' 2"

No. 1 & Appearance

13' 6"

17' 9"

22' 8"

27' 7"

No. 2

12' 4"

16' 3"

20' 9"

25' 3"

No. 3

9' 4"

12' 4"

15' 8"

19' 1"

Douglas Fir, Larch
(North)

Select structural
or No. 1 & Appearance

14' 1"

18' 6"

23' 8"

28' 9"

No. 2

13' 9"

18' 2"

23' 2"

28' 2"

No. 3

11' 1"

14' 8"

18' 8"

22' 9"

Eastern Hemlock-
Tamarack (North)

Select structural
or No. 1 & Appearance

12' 7"

16' 7"

21' 2"

25' 9"

No. 2

11' 11"

15' 9"

20' 1"

24' 5"

No. 3

10' 3"

13' 6"

17' 2"

20' 11"

Hem-Fir (North)

Select structural
or No. 1 & Appearance

13' 3"

17' 5"

22' 3"

27' 1"

No. 2

12' 11"

17' 0"

21' 8"

26' 5"

No. 3

9' 11"

13' 1"

16' 8"

20' 3"

Ponderosa Pine

Select structural
or No. 1 & Appearance

12' 3"

16' 2"

20' 8"

25' 1"

No. 2

11' 11"

15' 8"

20' 0"

24' 4"

No. 3

9' 1"

12' 0"

15' 4"

18' 8"

Red Pine

Select structural or No. 1 & Appearance

12' 7"

16' 7"

21' 2"

25' 9"

No. 2

11' 9"

15' 5"

19' 9"

24' 0"

No. 3

8' 11"

11' 9"

15' 0"

18' 3"

Spruce Pine Fir

Select structural

13' 3"

17' 5"

22' 3"

27' 1"

No. 1 & Appearance

13' 2"

17' 5"

22' 2"

27' 0"

No. 2

12' 0"

15' 10"

20' 3"

24' 8"

No. 3

9' 1"

12' 0"

15' 4"

18' 8"

Western Cedars
(North)

Select structural
or No. 1 & Appearance

11' 11"

15' 9"

20' 1"

24' 5"

No. 2

11' 7"

15' 3"

19' 5"

23' 7"

No. 3

9' 4"

12' 4"

15' 8"

19' 1"

Western White Pine

Select structural

12' 11"

17' 0"

21' 9"

26' 5"

No. 1 & Appearance

12' 11"

17' 0"

21' 8"

26' 6"

No. 2

11' 7"

15' 3"

19' 5"

23' 8"

No. 3

8' 11"

11' 9"

15' 0"

18' 3"