Joist Span Table for Floor Joists
Floor Joist Span Tables for various Sizes and Species of Wood
Joist span table - Use these tables to determine floor joist spans based on grade of lumber, size of joist, floor joist spacing, and a live load of 30 lbs/ft2 or 40 lbs/ft2. These tables can also be used to determine deck joist span.
For example, in the joist span table below, the highlighted cell shows that 2" x 8" Southern Yellow Pine joists, that have a grade of #2, and are spaced 24" apart can have a maximum span of 10 feet - 3 inches (10-3) if designing for a live load of 40 lbs/ft2.
Note: The span information in these floor joist span tables is for quick reference only. Wood structural design data has been updated since this page was created. For the latest up-to-date floor joist span data, please use the Span Calculator on the American Wood Council website.
Floor Joist Span Table
| Size | Spaced (o.c.) | Species/Grade ( 30 lb/ft2. Live Ld) | |||
| Y. Pine | Y. Pine | Doug. Fir | E. Spruce | ||
| #1 grade | #2 grade | #2 grade | Structural | ||
| 2" x 6" | 12 | 12-6 | 11-3 | 12-0 | 11-0 |
| 16 | 11-4 | 10-10 | 10-11 | 10-0 | |
| 24 | 9-11 | 8-8 | 9-7 | 8-9 | |
| 2" x 8" | 12 | 16-6 | 14-11 | 15-10 | 14-6 |
| 16 | 15-0 | 13-6 | 14-5 | 13-2 | |
| 24 | 13-1 | 11-6 | 12-7 | 11-6 | |
| 2" x 10" | 12 | 21-0 | 19-0 | 20-3 | 18-6 |
| 16 | 19-1 | 17-3 | 18-5 | 16-10 | |
| 24 | 16-8 | 14-7 | 16-1 | 14-8 | |
| 2" x 12" | 12 | 25-7 | 23-1 | 24-8 | 22-6 |
| 16 | 23-3 | 21-0 | 22-5 | 20-6 | |
| 24 | 20-3 | 17-9 | 19-7 | 17-11 | |
| Size | Spaced (o.c.) | Species/Grade ( 40 lb/ft2. Live Ld) | |||
| Y. Pine | Y. Pine | Doug. Fir | E. Spruce | ||
| #1 grade | #2 grade | #2 grade | Structural | ||
| 2" x 6" | 12 | 11-4 | 10-3 | 10-11 | 10-1 |
| 16 | 10-4 | 9-4 | 9-11 | 9-2 | |
| 24 | 9-0 | 7-9 | 8-8 | 7-11 | |
| 2" x 8" | 12 | 15-0 | 13-6 | 14-5 | 13-2 |
| 16 | 13-7 | 12-3 | 13-1 | 12-0 | |
| 24 | 11-11 | 10-3 | 11-3 | 10-6 | |
| 2" x 10" | 12 | 19-1 | 17-3 | 18-5 | 16-10 |
| 16 | 17-4 | 15-8 | 16-9 | 15-3 | |
| 24 | 15-2 | 13-1 | 14-6 | 13-4 | |
| 2" x 12" | 12 | 23-3 | 21-0 | 22-5 | 20-6 |
| 16 | 21-1 | 19-1 | 20-4 | 18-7 | |
| 24 | 18-5 | 15-11 | 17-6 | 16-3 | |
The above spans are based on American Softwood Lumber standard sizes.
For additional species of lumber, check out the Joist Span Calculator from the American Wood Council website.
** Note: The data in the floor joist span tables above was obtained from Architectural Drawing and Light Construction by Edward J. Muller.
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