Looking to stiffen floor a little and remove a lally column. Currently the column supports 3 floor joists at the center of a 14 foot span. I was looking to remove this column and give myself some more room. I was going to build a 14 foot beam to support all the joists across the span. Can anyone tell me what size beam I should build, or where to find load chart to figure it out.
I was planning on using 2 x 12 x 16, 3 glues and bolted up with sandwiched 1/2 plywood. supported at either end.
The floor joist currently span about 16 feet and are old lumber 2 x 8 balloon framed of course.
Thanks in advance
JRE
Replies
I don't give out advice on beams unless I can look over a situation myself. Too many variables, like local codes and stuff you might have overlooked.
I'd suggest getting someone local to look the situation over first hand.
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Like Boss said, it can be dangerous to seek or give important strctural advice like this without asesing the situation. One key piece of info you leave out is whether anything from above on the roof and/or seond story loads onto this floor system.
But most lumberyards that sell engineered lumber can size it for you.
And engineered lumber is the only way to do this right, IMO. You might be able to do it with a flitchbeam by adding steel between wood or get an engineer to size an I-beam for you, which will give the best headroom, or you can let the beam up into the joist set to gain headroom also.
but since this is such an old house, odds are good that you have no footing support in place for the posts that will have to support both ends of this beam so consider that.
Another option would be to sister the existing floor joists with new 2x12s. That would only cost you about three inches of headroom and no need for any support posts.
to comment on what you propose, it would probably be better than what you have now certainly but it would not pass muster in the books, and the plywood would not do anything for you.. Also - why buy them sixteen feet long when ytou are only spanning 14'? Just buy fourteen footers if you elect to go that way.
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I would second Boss's advice to get a pro to look at it in person. There are too many possibilities that internet advice would miss a small but critical element in your situation.
As to the glue and ply that you plan to use, forget them. Construction adhesive is not structural and the plywood will add very little strength. Ply is used between headers to pad the doubled 2x's to the wall thickness, not really for strength.
Jon Blakemore
Like said before, the ply is useless, forget it.
If intent on a well done DIY job, get a copy of a structual text on 'built up beams', such as the classic "Strength of Materials" by Timesheko and Young or equivalent on the internet. If you can understand the text and shear and tensile equations, adding a well bolted* steel plate to the bottom of the joists is the easiest thing to do if you have an air impact driver of big 3/4 drill to drive the bolts. Otherwise, get somebody to look that knows, as others have said.
* a 6 by 12 glue lam can have it's strength doubled by bolting a 1/4' thick 5" wide steel plate to the bottom, you do need about 40+ 3/8 3" long lag bolts and the bolt spacing is critical, more toward the supports than at the middle, somewhat counter-intuitive until you understand the stresses.