huangyhg

question regarding floor support beam installation
hello,
i hired a contractor to build a room addition. the single storey room has a concrete basement with standard wood frame construction built on the basements walls. the room is about 26 feet long x 19 feet wide. the 2 x 10 syp wood floor joists run lengthwise along the 26' span & hang over one of the basement walls (along the 26' span) by about 4 feet. the joists are 18" o.c. & are supported by an 8 x 5-1/2" steel "i" beam, located at the center of the 22 foot span of the basement walls (26 - 4 = 22).
the joists "overlap" each other at the steel beam (by a couple feet) and do not run the full 26' length.
the basement walls are 8" thick, and the steel "i" beam fits down into "notches" in the center of the two 22'long walls.
the steel "i" beam is supported by a round hollow steel support tube at the center of the approximate 19' span of the steel "i" beam. the support tube is about 4-1/2" in diameter & has a threaded height adjustment on the bottom. the bottom of the tube is connected to a steel "pad" that is bolted to the concrete floor. the top of the tube connects with a bracket that is "wrapped around" the bottom of the "i" beam.
however, the ends of the steel "i" beam are not sitting down on the concrete walls, and are not touching the basement walls in any way. the "i" beam is being completely supported by the steel support tube in the center of the 19' span of the "i" beam.
they cut a few steel shims and put them under each end of the steel "i" beam, between the beam and the concrete walls (shims are about 1/8" to 3/16" thick x 2-1/2" wide x 6" long. they have two shims on one side, and one shim on the other.
however, there is still a 1/8" to 1/4" gap on each end, between the bottom of the steel "i" beam and the shims. so, the steel "i" beam is being completely supported by the support tube, and not the basement walls.
is this the correct way to install the "i" beam ? the contractor said it was, and that there would be some settling.
it just seems to me that the steel beam should be supported by the basement walls on each end (i.e., it should be sitting on the basement walls) and then the steel support tube should just "support" the center of the steel beam, and not be the "only" thing that holds the entire beam (and the center of the floor) in mid air.
i suppose if the center support beam would change in length due to ambient air temperature, then this might be one reason to leave a gap at each end of the "i" beam. if the center support beam were to shorten due to temperature changes, then it could pull the bolts out of the concrete floor (or at least loosen them) since the support tube is fastened to the "i" beam. i suppose the "i" beam could change a little in size as well, but i would not think it would be much.
it seems to me any settling would just make the gaps bigger at each end of the steel beam.
i would appreciate it if someone could please educate me a little in this area and explain the proper way to install a steel support beam in a situation like this, and explain why it is done that way.
thanks for your help.
john
at the very least you would want vertical support on the walls via steel packers or grout, a clear gap is not the correct way! the requirement for bolting would depend on local requirements/practice and if uplift or lateral loading is an issue.
is the floor above bouncy? if not, the beam ends may be getting some support via the joists and wall above, but it is not support that should be relied on.
hi apsix,
thanks for your reply.
when you say to use "packers" do you just mean steel shims that go between the steel beam and the concrete walls ? i thought of trying to machine a steel shim that would provide a good fit without gaps, but it looks like it might be tough since the concrete underneath is not perfectly straight or flat.
would a wood shim be acceptable, or would it not have enough compressive strength ? i am not sure how much weight is really on the beam.
i am guessing that it would not be good idea to just cement underneath the steel beam, since it probably has to move a little lengthwise, do to length changes from ambient air temperature changes.
the top of the steel beam is even with the bottom of the wood sill plate on the basement walls, and there is a wood sill plate on top of the steel beam as well. i don't think the joist could be providing support to the steel beam, but i did notice that they put some nails into the sill plate on top of the steel beam, and then bent them around the top edge of the steel "i" beam. i am not sure what they were really trying to do there.
i have not noticed any bounce in the floor just walking on it, but i could jump on the floor near the end of the beam to test it. we have not moved into the room yet, as they still have to do the finish work inside, paint, trim, etc..
the floor does "squeak" sometimes and i think this is because of the cheap stamped metal "stringers" they put between the joists. i like to just use 2 x 10 wood stringers between the joists, and i don't like these new metal ones. they just have a "fork" that sticks into one joist on one side, (no nail) and one nail to connect to the joist on the other side. they did use construction adhesive when they put the 3/4" thick osb flooring down, and it really sounds like the creeping noises are coming from the metal stringers.
if i were building this myself, i would have just set the ends of the steel beam directly on the concrete walls for vertical support (down in the notch, with horizontal clearance at the ends to allow for lengthwise expansion) or put a hard rubber pad between the bottom of steel beam ends & the concrete walls. then, either mill the thickness of the sill plate on top of the steel beam to match the ones on the concrete walls, or mill a shim that would make the sill plates match up.
it looks to me like they just used the adjustment screw at the bottom of the center steel support tube, to raise the steel beam & match the sill plate on top of the steel beam, with the sill plates that are on the concrete walls. when they did this, it raised the ends of the steel beam right off the concrete walls.
what is the correct way to do this right from the start ?
and now, since everything is already in place, what would be the best way to fill in the gap underneath the steel beam and provide support for the ends ?
i would appreciate any further feedback from you and/or other forum members on this issue.
thanks again for your help.
john

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