My house uses 2x8s for the first story flooring, and they span a wee bit too far for 2x8s at about 12' 8" or so.
The floor upstairs is bouncy. Not horrible, but enough.
Problem is, we'd like to, in the not to distant future, put engineered wood flooring and/or tile/stone down, and are concerned that the floor will just not take the weight as-is.
Further complicating is that the basement is split into 2 sections. 1 section is a 4' high crawlspace with poured floor. THAT section I figure I can put a stiffener beam down the middle of and put a jackpost every 5" if I have to, even on just the poured floor.
The other half is a full height (8' ish) poured floor area that I've converted to my woodshop. Since it's my woodshop, and it's net dimensions are about 12' 3" x 23 feet, I really don't want to slap a jackpost in the middle of it (it would be right where my tablesaw is) - it's already hard enough to maneuver large sheetgoods.
What I do have is some headroom to play with. The main HVAC trunk lines already run right down the middle and take about 12" off the headroom. I was thinking I can get an LVL in the range of 4" x 12" x 23' and run it next to the trunks, not lose any headroom, and this might be enough to take out the bounce without having to take the full weight like a normal beam. I can spare the space at the ends to support it with a jackpost or a couple of 2x4s nailed together.
One end would be up against a concrete wall, so the footings underneat that would come into play a bit, expecially if I nail the 2x4s TO the foundation wall. On the other end, I have a partition wall that divides the shop from the furnace/water heater area. I could beef up that wall with more 2x4s, and set the LVL into a pocket there.
I can't do sistered joists from below or above because of all the mechanicals and wiring and plumbing and spray insulation.
I might get 30% of them with plywood sistering with notches cut for wiring and such.
I did read about a bowstring truss technique, and also wonder if that would suffice here - if I have enough room for doing that, since those darn HVAC trunks are there.
Anyway, am I crazy thinking a beefy LVL could do the job with that kind of span?