I've seen and used the span table link many many times. But I have a little different of a question.

One of the rooms I'll be adding on will be 28' long by 15'deep (outside deminisions). This is going to be a great room partitioned at the end may or may not be another room.

To achieve the minimum clearance of 18" to my joists i'm going to need to use 2x6 joists. I'll probably be doing a 2x6 or 2x8 ( I like overkill) wood stem wall on a continuous concrete footer. At least this is how i'll have it drawn up.

Could I use 4x6 or 6x6 beams to span that 15' distance at 6' apart and then use joist hangers to the hang my 2x6's? The 2x6 joist span meets code at 6'.

But i'm not finding much about beam spans.

If nessecary I may cut that 15' deep distance in half with a second stem wall. But if the 4x6's or 6x6's will easily span that then why bother.

That or I could use spot peirs.

Big_Mounde