Beam question

Allthunbs · 01-29-2011, 08:47 PM

I have a beam about 36' long. It is made up of 3 2x10s SPF #2 and supports only the floor above. Joists are 2x8s, 14' long on 12" centres. I'm going to add blocking between the joists to stiffen them up a bit.

The beam is supported about half way by a lally column. At about the 8' mark there used to be a door. The jam was made up of 3 2x4s nailed together in a really weird configuration. At best, only one of the 2x4s could be load bearing but I can't be sure just looking at it. Now, I want to remove those 2x4s but all the beam tables I can find say those 2x4s are structural. But, if they were structural they would be put together in a block. These are not.

I'm trying to figure out if I can remove the three 2x4s or what is my maximum unsupported beam span. My last house had a similar beam supported every 12' but that beam was load bearing and supporting a second story and the roof.

Your assistance is appreciated.

AndyGump · 01-30-2011, 12:03 AM

Not too sure what you got going on there but I would consult an engineer on this one.

Andy.

**Gary in WA** · 01-30-2011, 12:13 AM

Definitely see a Structural Engineer. A SPF#2 4x10 (similar) has a fb of 1000#. With an 18' span it could carry 1848#total. If your joists are 14' on each side, the beam is carrying 14' of floor= 40#live load, 15# dead load= 55# x 14= 770# total x the span, 18'?= 13,860#..... You are missing a few bearing posts, if this is correct.... don't remove anything.

Gary

fungku · 01-30-2011, 12:19 AM

Photos? And three questions:

Are the joists 14' going each direction from the beam?
Is there a wall on the floor above the beam?
Is the the door in a wall running perpendicular to the beam and crosses it's span @ 8'?

3-2x10 SPF#2 built-up floor beam supporting one floor and 14' of floor joists has a maximum span of 9'-8"

And you seem to be implying that you have one bearing support @ about 18'? There should be at least two more, but the wall the door is in may be one of them. :P

Whatever is going on there does not sound right and you should have an engineer look at it.

Allthunbs · 01-30-2011, 07:29 AM

Exactly what I needed. Thanks to everyone.

I don't know about your neck of the woods but getting an engineer in my region is almost impossible. When you find one, they don't want to do the work because of liability issues or they're expert in another field and don't want to stick their necks out.

What I've been told here makes me go back and increase the structuring, not decrease it. Thanks again.