This section is from the book "Building Construction And Superintendence", by F. E. Kidder. Also available from Amazon: Building Construction And Superintendence.
C. Slate Roofs Plastered, or Gravel Roofs Not Plastered.*
Total load, 66 pounds per square foot.
Size of Joists. | Dist. on Centres. | Hemlock. | White Pine. | Spruce or Norway Pine. | Oregon or Texas Pine. | Georgia Pine. | |||||
Ins. | Ft. | Ins. | Ft | Ins. | Ft | Ins. | Ft. | Ins. | Ft. | Ins. | |
2x6 | 16 | 9 | 5 | 9 | 10 | 10 | 8 | 12 | 1 | 12 | 9 |
2x6 | 20 | 8 | 6 | 8 | 10 | 9 | 6 | 10 | 9 | 11 | 5 |
3x6 | 16 | 11 | 7 | 12 | 1 | 13 | 1 | 14 | 10 | 15 | 7 |
3x6 | 20 | 10 | 4 | 10 | 10 | 11 | 8 | 13 | 3 | 14 | 0 |
2x8 | 16 | 72 | 7 | 13 | 2 | 14 | 2 | 16 | 2 | 17 | 0 |
2x8 | 20 | II | 3 | 11 | 9 | 12 | 9 | 14 | 5 | 15 | 2 |
2x8 | 24 | 10 | 3 | 10 | 9 | 11 | 7 | 13 | 2 | 13 | 10 |
3x8 | 16 | 15 | 5 | 16 | 1 | 17 | 5 | 19 | 9 | 20 | 10 |
3x8 | 20 | 13 | 9 | 14 | 5 | 15 | 3 | 17 | 8 | 18 | 8 |
3x8 | 24 | 12 | 7 | 13 | 2 | 14 | 2 | 16 | 2 | 17 | 0 |
2x10 | 16 | 15 | 9 | 16 | 6 | 17 | 9 | 20 | 2 | 21 | 3 |
2x10 | 20 | 14 | 1 | 14 | 8 | 15 | 11 | 18 | 0 | 19 | 0 |
2x10 | 24 | 12 | 10 | 13 | 5 | 14 | 6 | 16 | 6 | 17 | 5 |
2x12 | 16 | 18 | 10 | 19 | 9 | 21 | 4 | 24 | 2 | 25 | 6 |
2x12 | 20 | 16 | 10 | 17 | 8 | 19 | 1 | 21 | 8 | 22 | 10 |
2x12 | 24 | 15 | 5 | 16 | 1 | 17 | 5 | 19 | 9 | 20 | 10 |
* These tables are intended for climates where a snow fall of a feet may be expected. In the Southern States, where there is no snow to speak of, the spans in the first section will be sale for slate or gravel roofs if the joists are sawn full to dimensions.
 
Continue to: