Beam span for mezzanine

[countrybumpkin]

I'm fixing to build a mezzanine in my new shop, it's going to be 12 X 30 , floor joists are going to span the 12 foot distance with 5/8 or 3/4 tongue and groove floor. I'm wanting to try and span one of the 30 ft distances with 4 post , one post at each end and then one post at 8 ft from each end giving me a 14 ft clear span in the center. Would this be doable with a couple of LVLs or a glulam.

 

[Mace Canute]

I'm fixing to build a mezzanine in my new shop, it's going to be 12 X 30 , floor joists are going to span the 12 foot distance with 5/8 or 3/4 tongue and groove floor. I'm wanting to try and span one of the 30 ft distances with 4 post , one post at each end and then one post at 8 ft from each end giving me a 14 ft clear span in the center. Would this be doable with a couple of LVLs or a glulam.

How much weight do you expect to have on the mezzanine floor?

 

[rtimgray]

In my opinion, without knowing your load, a doubled 2x12 would probably be just fine, possibly overkill. I have a loft of similar dimensions (12' deep x 30' wide, one post in the middle of the 30' span). I used 2x6 joists resting on a ledger on the wall and then attached to a 2x12 on the other end. It has 5/8" t&g plywood for a floor, but I only use it for light storage. It's been there for 10 years or so with no sag.

Of course, if you're wanting to really load up, you might need to get a larger beam.

Good luck and take care.

 

[countrybumpkin]

Whoops sorry, guess load and intended use would be critical info.

Mainly just over flow box storage maybe a shelf or two for a few cases of oil and paint cans. Bunch of junk that I probably should get rid of anyway, Nothing real heavy.

 

[LD1]

Pretty simple to walk through the math.

50PSF is probably more than you are going to store in boxes, and what most floors in houses are designed around. Add 10 PSF for a dead load. So 60 pounds per square foot.

The beam is only gonna carry 6' of the 12' joists. (whatever is opposite the beam will carry the other half).

So your 14' span beam will need to carry 360PLF (# per linear ft) of distributed load.

So, you can look at this table and pick what you like. Or adjust loading accordingly if you think you will store more or less up there http://www.southernpine.com/app/uploads/AL_21-26L.pdf

According to that and the 360plf example I gave....

Triple #1 2x12's come close at 355plf for a 14' span. As do 4 #2's

At the bottom they list LVL's.
Double 9.5" beams (3.5" width) is not quite enough, double 11.25" beams is plenty.

OR you can use this table, which is just a generic table for 40psf live 10psf dead loads
http://www.southernpine.com/app/uploads/SS_13-14L.pdf

 

[LD1]

In my opinion, without knowing your load, a doubled 2x12 would probably be just fine, possibly overkill. I have a loft of similar dimensions (12' deep x 30' wide, one post in the middle of the 30' span). I used 2x6 joists resting on a ledger on the wall and then attached to a 2x12 on the other end. It has 5/8" t&g plywood for a floor, but I only use it for light storage. It's been there for 10 years or so with no sag.

Of course, if you're wanting to really load up, you might need to get a larger beam.

Good luck and take care.

Hard to believe you are spanning 15' with a single 2x12 and carrying joists from a 12' floor and no sag? Hardwood beam?

That beam should be allowed no more than 90 PLF total load. Thats 15# per square foot and you are probably eating half that with the flooring.

IS it springy or soft to walk on? I would think that would feel like a trampoline up there.