I'm finishing a basement and I'd like to see if it's possible to move the ceiling jack post that holds the beam where the floor joists sit on. I currently have a 12 foot span between the cinder block wall and the ceiling jack that holds the triple up-ed 2×10 beam, and I'd to move the span to 15 feet. I have a cinder block foundation and most of the weight from the house is on that.
Photo is included here for visual reference.
Ben
Best Answer
Three feet doesn't sound like much, but for a high-stress beam it is. You'll probably need to convert from solid wood to LVL or steel at a prescribed size. As you say, most of the weight of the home is on the block foundation. That still leaves a few tons on the beam, and you don't guess with that kind of load.
The larger problem, though, is that you may not have a footing where you'd like the post to go. It's typical to see a 36" square footing poured under the slab at point locations such as this, and you'd need to cut open the floor to add a new footing (10-12" thick on undisturbed soil). Not doing so would probably result in settling and cracking of the slab, and therefore sagging of your house in undesirable ways.
Get a professional to take a look with you. This is no question for a bunch of yahoos on the internet.