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harleysilo 01-02-2007 09:28 AM

10' Beam instructions needed.....
Hi everyone! I've finished several support walls in part of my basement, the ones under the kitchen/pantry part of a hallway. I've also finsihed sistering about 80% of the floor joists that I need to. I am now to an area in the basement where the two previous solutions I've used will either severly intrude on the dynamics of the basement (another wall) or be near impossible to install (sistering joists.) So I need to build a beam.

The beam shall be 10' in length, Height and width will be whatever they need to be. It will be supported with two posts (material yet to be determined) at the 1' and 9' marks more or less.

The purpose of the beam is to reduce the span of the joists from 12' to 9'.
Current joists system is 2x10's 12' long 16 O.C. It's also a bathroom floor....the area i want to help support.

So would something like 3 2x12's with 2 pieces of plywood, glued an nailed sufice?

Once in place, I'll probably jack the sucker up a tad to slide my posts in place.

see diagram.... when I've built the couple of supporting walls, the wall header was able to go up or down slightly to make up for the differences, plus I cut each wall stud to fit exactly so no gaps like will occur with beam....

Hube 01-02-2007 04:25 PM

common lumber yard stock, #2 SPRUCE lumber specs; 2x10 @ 16" centres can span up to 14'-6" andsafely support a live load of 40 lbs per sq. ft.

And "X" braces mid span will even make it slightly stronger.
Unless I'm missing something in your design, why do you need this additional support?

glennjanie 01-02-2007 04:42 PM

Yes, the bathroom floor probably could use this extra support. The beam you mentioned could hold up half the house, just make sure you stagger the joints in the plywood. The uneven joists could be notched to a uniform depth or you may use the shims to even them up on the beam; I personally think the notching would make a neater looking job.

harleysilo 01-03-2007 07:25 AM

Thanks for your replys. Here are some pictures to further explain the issue...

bathroom needing extra support for future tile...

Area I'd turn into U shaped bar....

Beam to reside between 2 a/c ducts, running parallel to doorway of small closet under stairway....

MayISee 05-14-2007 07:45 AM

Please more Detail on Beam Construction for newbie
I am close to attempting to install a similar 10' beam.
For similar reasons
Under my bathroom (and Kitchen in my case)

And would like to know more ... about constructing such a support

I assume I can figure out the beam itself (2 to 3 2 by-somethings together)
?Posts would be lally columns?

?What should the beam rest on?
Steel plate at top between post and beam?

- Under posts -
? Should I break out some floor?
? Just pour some concrete on existing floor?
? Just put columns right on the existing floor?

glennjanie 05-14-2007 10:22 AM

Welcome MayISee:
Your beam could be 3/8" steel plate sandwiched between 2 2X8s bolted each foot, staggering top to bottom with 2 bolts on each end. Your 2 posts should be 3" schedule 80 steel pipe,with plates on top to fit the size of the beam. You should cut 16" squares out of the floor and dig to undisturbed earth. You could place concrete footings flush with the floor and the posts should have a 6" square 1/2" thick bearing plate on the bottom.
I wish you the best in your project.

Square Eye 05-14-2007 05:08 PM

Steel plate running the full length of a beam is very expensive and drilling for bolts every foot would take a professional quality heavy duty drill.
2x10s nailed and glued together have been the standard for a beam in the 10ft range for a very long time.
Heavy steel posts are fine. If you carefully fill them with concrete, they won't suffer from condensation and rust out at the bottoms which is common with hollow posts. If you do dig down through your floor as you should, Pour a concrete base, measure and cut your post to sit on the base then set the post plumb and pour concrete around it up to flush with the floor.
A steel plate on top of the post is fine. I'd recommend it, actually, if it were welded on it would be even better. Drill through the corners and lag screw the plate to the bottom of the beam.
Also consider what will keep the beam from just rolling over on it's side. You will need to either brace the beam in an upright position from the floor joists or terminate the ends into a wall or a post with a welded bracket at each end.

I am assuming that you are just trying to level some floors though. If you are having support issues under a wall or if there aren't any other posts or beams under your floor, you should consult an engineer or a qualified carpenter or contractor.

MayISee 05-15-2007 08:39 AM

Thanks for all advice, replies, I certainly need ALL input!!!

No, no leveling is needed.
No, the floors do not sag (that me, guests, the appliances, the current flooring notice)

I am putting pebbles (with lots O grout) on the bathroom floor
and may eventually put new tile down on the kitchen floor

These rooms are next to one another AND I want the floor stiffer so the grout and tile do not crack.

Structurally simplest seems to be an extra beam cutting the 11' span in half.
BUT if I knock out the X blocking and put in sister joists (and put some blocking back in) that might make a future home inspector happier ???

(No, I don't expect a home inspection anytime soon ...)

MayISee 06-04-2007 09:13 AM

1 Attachment(s)
I went with a new 6' x 14' laundry room, and that new wall supports the bathroom and kitchen underneath. Thanks for the help!

scottyf 10-03-2007 12:43 PM

I'm sure glenjanie and Square Eye are trying to be helpful, but taking recommendations from people on the internet about the structural portion of your house could be a poor decision. Hire a structural engineer, they'll figure everything out for you for likely < $600, cheap peace of mind if you ask me.

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