The plans call for a 2x12 4 ply beam to cross the living space from the stairs to outside wall to support the 2nd story floor joists. However my builder says that is not necessary. They are using 2x12 joists on 12" centers instead. They say it meets load requirements of 40live 10dead. Can anyone help confirm this or give advise?
http://awc.org/codes-standards/calculators-software/spancalc
#2 SPF @12oc w/ 40+10 load can go 20'7"... I'd check on I joists at that point. Speaking of points, look up, this is assuming no roof loads, etc.
So it sounds like the builder is right. I would still feel better with a beam, however it would be nice if it was smaller. How does a 2x8 4ply sound since its not really required?
Doubt it would do more than add weight, I'd need a plan to understand the problem.
12" depth spanning 20 feet is likely to cause floor bounce/vibration that is irritating to most people.
Has the foundation already been done? You would need footers for the posts that support the beams.
If you are going to span 20 feet, I think in the long run you'd be better off stepping up to some deeper I-Joists. It may also make the plumbing and electrical easier.
My wife and I are building the 2 story universal in the spring so I am pretty familiar with the plans.
It's the standard universal 20x34 plan. Nothing changed. Concrete done with footers in correct areas for posts. Its to late to change to I joists or engineered trusses as the dimensional joists are installed already. Just need to know if I can add a smaller support beam so it doesn't divide the living room ceiling like a 2x12 beam would.
You don't need to add a support beam. I didn't realize your house is already built. Like Don P said, you are not over span. Structurally, you are good to go.
Update:
The 2x12x20 had more bounce than i liked. We added 4 nailed and glued 2x8's, sitting on 6x6 post to cross the living room from stairs and the house is now perfect. No bounce at all once sheetrock was installed.