Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
Wood beam span table roof.
Span calculator for wood joists and rafters also available for the android os.
Span tables for domestic floor joists to bs 5268 7 1 note.
Also available for the android os.
Deflection for 30 psf live load.
For lesser grades spans should be shorter.
Strength live load of 30 psf plus dead load of 10 psf determines the required bending design value.
Raised wood floor foundations.
This means that some values are slightly more conservative than span tables from other sources if those do not include the amended guidance.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
Limited to span in inches divided by 360.
The tables below give maximum spans for rafters and beams.
Our floor joist span tables are based on loadings given in the newer amended version of bs 6399 1.
Tables 13 14.
Keep in mind that these are maximums in other words shortening spans slightly will result in a more solid structure.