[cekrauss]

My son just purchased his first house, a real project house. Built in 1950, the original single story structure was modified in the 70's to add a second floor. Covering a total span of approximately 15 ft on the second floor is a bath (about 10 ft) and part of a bedroom (5 ft). Each end of this total span is on top of a first floor load bearing wall which is in turn above a concrete block basement wall. The floor joists are dimensional 2 x 8s, 16" O.C. and appear to be fir. My son and I were gutting the bathroom for a remodel when we made this discovery. I'm pretty positive the 15' total span is beyond the maximum span for 2 x 8s. The existing ceiling height is already constrained so we really don't want to put in wider joists. My preferred option would be to sister another 2 x 8 to each joist or perhaps put in 2 x 8s in between the the existing ones, making them 8" O.C. The span calculators and tables I've looked at don't address either of these options. Any advice will be much appreciated. TIA.

 

[sixeightten]

Off the top of my head, I am pretty sure either way will not meet code. Doubling them up would probably be easier, and also stronger.

 

[Ron6519]

I'd add the lvl version of a 2x8. The problem with all the doubling up is the piping that runs through the joists and the limited space to drill holes.
Ron

 

[cekrauss]

I apologize Ron, I'm not sure what you mean by a "lvl version". My concern is, of course, for the safety and the integrity of the supports. You think this will work? Thanks!

 

[Ron6519]

I apologize Ron, I'm not sure what you mean by a "lvl version". My concern is, of course, for the safety and the integrity of the supports. You think this will work? Thanks!

LVL is an abbreviation for, "laminated veneer lumber". It's much more rigid then the same dimensional lumber cousin. It's actually 1 3/4" thick by, in the case of a 2x8, 7 1/2" wide.
Ron