Thread: Joist span

I'm thinking the span is too great here but not sure of exact length required for joists without support beam below.

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I took seminar by Journal of Light Construction and deck builder told us this as rule of thumb.
1/2 span plus 2 equal joist size.(16 inch on center)
If you have 14 foot span divided by 1/2 equals 7. Plus 2 equal 9. You need a 2x10.
2x12 no longer than 16 feet.
Lots of variables but not a bad rule of thumb in the field.
I also have table if you have the span and joist size.

It would be helpful to know both the joist span and the unsupported span of the deck edge beam as well as the size of the members.

For example: a 12 ft joist span with an 8 ft span on the edge beam, a dbl 2x10 #2 SYP would be sufficient considering a 40psf live load.
The same joist span with a 10 ft edge beam span would require a dbl 2x12 #2 SYP.

The size and span of supporting edge beams, headers and girders is all dependent on the live load and total load per LF exerted on the beam.