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The stair opening into my basement is framed like this:
stair opening framing
A partition wall (non-load bearing) sits on top of the header.

A square duct runs parallel to the header, and on the other side of this duct is an I-beam (3" x 3") supported in the center by a single adjustable steel column: I-beam and column / close up of tail joist-header connection Two small bolts (maybe diameter #10 or 1/4"?) run through the column flange and I-beam to fasten them together. The column sits on top of the concrete slab floor. There are no seams anywhere in the floor -- if there is a footing beneath the column, it was put in before the floor was poured.

My house has many modifications that are clearly DIY. This whole beam and column have a very "DIY" appearance.

Between the stair opening header and tail joists (which are end nailed) there is maybe 1/4" separation (max). This may just be due to the header being rotated slightly. I believe the previous owner may have noticed the separation and installed the support as a preventative measure. Or maybe there were floor vibration issues? If it were done professionally, I would expect the support directly under the header -- not some 14" away on the other side of the duct -- and a footing poured beneath the column.

I did deflection calculations with both uniform load and joist-point-load models and got similar results -- a max header deflection of about L/600. Additionally, the stairway opening basically meets the prescriptive code in my area (Wisconsin UDC). It would be code compliant if the header and tail joists were supported by framing anchors instead of just end nailed (house was built late 60s).

So I am thinking the header/trimmers by itself should be sufficient. I would like to
1. Install framing anchors on the tail joists and header "to be safe" (and meet code)
2. Remove the I-beam and column because they are in the way.

Solution not feasible -- see edit below.

I will wind up hiring a structural engineer to confirm, but before I pay $$ to have one come out I wanted see whether I was missing something obvious. So does anyone see a reason for that I-beam and column?

Thanks!!

EDIT: Additional deflection calculations estimate 40psf live load trimmer deflection (w/o I-beam) at 0.4" or ~L/360. I am betting this much deflection in the girders caused vibration issues.

Columns at either end of the header would lower deflection of trimmers to ~L/774. That would be a suitable solution, but would require tearing up the slab for column footings. I don't know a lot about concrete, but I am guessing doing so may be the only proper solution? I would put a load bearing wall in below the header instead were it acceptable to spread the load on the slab, but I am guessing even spread out, a load bearing wall like this would require a footing?

  • Are the floor joists each one piece (not butted over the I-beam or sistered somehow)? The photo seems to show left-most first three are not, but I can't tell for sure on those, and certainly not for the others. – wallyk Aug 17 '16 at 19:36
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    Your terminology needs help. You don't have trimmers or headers in that scenario. You have joists acting as flush beams, one or more of which is a girder (carrying another beam). – isherwood Aug 17 '16 at 20:45
  • @wallyk The joists are all one piece. The tail joists begin at the foundation wall, rest on the I-beam as pictured and continue to the header, where they are end nailed. – jmvincent Aug 19 '16 at 19:56
  • @isherwood I have always heard the members called headers and trimmers regardless of the orientation of the opening. Documents from the APA and WWPA use this same terminology, for example. Both function as girders, as you mentioned. – jmvincent Aug 19 '16 at 20:14
  • Headers and trimmers are both wall components, in my extensive experience. I've never heard them used in the context of floor structures. YMMV. – isherwood Aug 19 '16 at 20:16
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2x8s aren't adequate for floor joists by modern standards, let alone for beams (even doubled). Someone probably added the steel beam and post due to floor bounce or sag. My former home had something nearly identical underneath where a fireplace was added.

I'd either leave it in place or bolster the doubled 2x8s that are along the duct with additional support in other ways:

  1. Add another beam underneath them.
  2. Replace them with a 3-1/2" laminated beam of the appropriate height (consult an engineer).
  3. Add a post to halve the span. This would require adequate footing structure, of course.
  • I hope they used more than one column, that setup ain't right(pictured). – Chris Aug 19 '16 at 3:58
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    If a system is securely anchored and supported at each end, a single-column arrangement adds substantial support. – isherwood Aug 19 '16 at 13:10
  • Thanks for the response. My house is only 24' wide, so that joist floor deflects at ~L/386 under 40psf live load, which is even good enough for ceramic tile. After reading your comment about the girders I realized I didn't consider the trimmers-- turns out they are probably the weak link (see edited OP). I would love to do a bearing wall instead of columns if it meant not cutting up the slab, but I would be surprised if the bearing wall did not also require a footing? – jmvincent Aug 19 '16 at 20:57
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    Yes, a bearing wall would also technically require a full footing. – isherwood Aug 19 '16 at 21:08
  • I am marking this as the answer-- I am planning to put a column at either end of the header to support the header and trimmers as described in the OP edit. – jmvincent Aug 28 '16 at 16:21
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I'd bolster the two trimmers by sistering on more 2x stock. And I'd bolster the header by hanging a second header underneath the existing header, hanging it on the trimmers using diy joist hangers ... strap iron bent over the top of trimmers (notched 1/2") and bent down again along the backface/outside of the trimmers. And get rid of the ibeam and post.

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