Need Beam Spec Advice

[maryaq]

Hi!
Upon trying to gird up my garage ceiling/attic floor, we replaced all the rotted/termite damaged joists with sistered 2x8s (same as original size). They sit in the walls. not sure what to call that. The span is 20'. The guys helping us put up a supporting beam under the joists. It's sistered 2x10s with the laminated part in between. Not sure if I'm describing that right. However, each side is resting on 6x6 posts, on one side, a few inches away from the wall unconnected and the other side is 2 feet from the wall to allow space for a staircase. The beam also only reaches to under only one of the sistered joists at each end, not both.

I think I actually need to get a longer/sturdier beam that goes all the way across the 20' span (and move the staircase). I'd like to use the loft space above for storage and/or fun kid area so it has to be sturdy and I don't want another sagging ceiling like before.

What kind of beam do I need? again, 20x20 space, sistered 2x8 joists 20" apart.
welcome any suggestions. thanks in advance.

 

[ard]

a picture and/or rough drawing would do wonders for a response....

 

[GMCGarage]

Hi!
Upon trying to gird up my garage ceiling/attic floor, we replaced all the rotted/termite damaged joists with sistered 2x8s (same as original size). They sit in the walls. not sure what to call that. The span is 20'. The guys helping us put up a supporting beam under the joists. It's sistered 2x10s with the laminated part in between. Not sure if I'm describing that right. However, each side is resting on 6x6 posts, on one side, a few inches away from the wall unconnected and the other side is 2 feet from the wall to allow space for a staircase. The beam also only reaches to under only one of the sistered joists at each end, not both.

I think I actually need to get a longer/sturdier beam that goes all the way across the 20' span (and move the staircase). I'd like to use the loft space above for storage and/or fun kid area so it has to be sturdy and I don't want another sagging ceiling like before.

What kind of beam do I need? again, 20x20 space, sistered 2x8 joists 20" apart.
welcome any suggestions. thanks in advance.

You need a beam that will hold up the load. Can you draw up a sketch and dimensions? Sure you want your kids playing in a space that is cobbled together from advice from the interweb?

 

[PAToyota]

Sure you want your kids playing in a space that is cobbled together from advice from the interweb?

Yep. Contact a local structural engineer to take a look at the loads, span, and other factors and give you a beam size and the support required.

 

[bigdav160]

Double 2x8 should have no problem with the span (17' if I read your description correctly) but is likely too small for use as a floor joist without considerable deflection.

 

[GMCGarage]

Double 2x8 should have no problem with the span (17' if I read your description correctly) but is likely too small for use as a floor joist without considerable deflection.

A double 2x8 is no where close to working, about 100% over stressed for floor loading. Also he said the original is rotted, so would not count on that at all. A 2x8 is good for about 10' span in his situation, so a beam down the middle is needed.

 

[3onthetree]

The 2x8 over 20' allows you to hang drywall, that's it. The (2) 2x10x17'-6" (what's the lamination you talk of, a flitch plate?) is undersized and floating in space. The 6x6, although huge, are unsupported by the slab. Any stairway framing should be accomplished within the joist section, not by shortening the beam (in this case).

You can use engineered lumber or steel for the beam, but your wallet, lead time, ceiling height, and know-how of whoever's raising it will help the architect/engineer you hire make that determination. Until then you might not want to park under or let anyone play in the attic.