These joist span tables are taken from the National Building Code of Canada, 1998 BC Edition (still current) and are for reference only. The final authority in building codes, including joist spans, lies with the building inspector in your local area. To improve the span of floor joists it is recommended to use 5/8" tongue and groove standard sheathing grade sub-floor, glued and screwed, with bridging between the joists and strapping below the joists. If the ceiling is finished below the floor, drywall is considered strapping.
Species | Dimension | Spacing of Joists with Strapping and Bridging | ||
---|---|---|---|---|
12" | 16" | 24" | ||
Hemlock Fir | 2x4 | 6'-10 | 6'-2 | 5'-5 |
2x6 | 10'-9 | 9'-9 | 8'-7 | |
2x8 | 13'-9 | 12'-9 | 11'-3 | |
2x10 | 15'-10 | 14'-9 | 13'-9 | |
2x12 | 17'-9 | 16'-7 | 15'-5 | |
Spruce Pine Fir | 2x4 | 6'-6 | 5'-11 | 5'-2 |
2x6 | 10'-3 | 9'-4 | 8'-1 | |
2x8 | 13'-1 | 12'-2 | 10'-8 | |
2x10 | 15'-1 | 14'-1 | 13'-1 | |
2x12 | 16'-11 | 15'-9 | 14'-8 |
Species | Dimension | Spacing of Joists with Strapping and Bridging | ||
---|---|---|---|---|
12" | 16" | 24" | ||
Hemlock Fir | 2x4 | 10'-8 | 9'-9 | 8'-6 |
2x6 | 16'-1 | 15'-4 | 13'-4 | |
2x8 | 22'-2 | 20'-1 | 17'-7 | |
2x10 | 28'-3 | 25'-8 | 22'-5 | |
2x12 | 34'-5 | 31'-3 | 27'-4 | |
Spruce Pine Fir | 2x4 | 10'-2 | 9'-3 | 8'-1 |
2x6 | 16'-1 | 14'-7 | 12'-9 | |
2x8 | 21'-1 | 19'-2 | 16'-9 | |
2x10 | 26'-11 | 24'-6 | 21'-4 | |
2x12 | 32'-9 | 29'-10 | 26'-0 |
Dave
(Ask Dave) (About Dave)Hi, I'm Dave Osborne. With over 50 years experience as a journeyman carpenter, foreman and contractor in heavy construction I enjoyed working with apprentices and sharing the tricks of the trade that others shared with me. Now I get emails from Members all over the world and we include many of my answers in our Free Monthly Newsletters. Some of my answers include drawings and instructions specific to a project, but may also answer your questions. I use correct construction terminology, so you can confidently inform your building supply dealers or contractors exactly what you need.
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