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House was built in 1939. I'm finishing the basement and want to open up the space under the staircase. There was a sort of closet under there, it was enclosed with some thin wood paneling and a plywood door. I removed those and this is what's left. There is a sort of old 4 x 4 lagged to the concrete floor. The vertical lumber is attached to this, 2 are old 3 x 3 ish and then a 2 x 4. All cut at an angle at the top and just seemed to be nailed to the bottom of the stringer. See the attached pics. I'm thinking this was just put up to make the walls for the closet but need to double check before I demo it.

UPDATE : Adding some more pics of the header connection. The stringers on the side are definitely one piece 1930s 2 x 10s top to bottom. Which measure 1 3/4 x 9. The center stringer is a 2 x 4 with triangle cut outs added to fill the gap to the treads. Stairs are 32 in. wide. The post at the header end isn't even touching the joist of the floor above. The one short peice of 2x4 at the footer was blocking for the drywall. I didn't remove the green sheet of drywall, it's big piece of the ceiling but i think we can see enough. There's a double joist at the top there.

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  • Please remove parts of the purple & green panel and take a picture of the stringer header and its support, from header to ground. If the stringer is one-piece, and the header is properly dimensioned and supported, the studs can go.
    – P2000
    Mar 3 at 20:54
  • The post doesn't need to touch the floor to impact its strength. The post touches the stringer, and the stringer has a shelf surface for the floor to sit upon. Suppose, for instance, that the header connects into a joist at both ends. Further, suppose that somebody cut through half of one of these joists's height right beside the header to joist connection. In this case, the joist has lost much of its bending strength and wants to sag. In this scenario, the header would be holding up the joist. The load path would include the tallest post.
    – popham
    Mar 3 at 22:33
  • I added more pictures where the stringers meet the header. I do know that the joists there are solid other than some small bores for wiring and one water supply line. It's still mostly as built in '39. Center stair colonial, longest unsupported joist is 10 ft.
    – tymish
    Mar 4 at 0:01
  • @tymish it looks like the stringer at one side is supported by the wall and at the other side by the post. To fasten it properly to the header, you can use "stringer hangers". If that cross lumber is not a joist or a header supported by joists, you'll have to ensure it hangs from joists, and you can use "joist hangers" for that. If you can upload a sketch of your current framing -as best as you can determine-, we can find applicable framing and support examples.
    – P2000
    Mar 4 at 1:04
  • @P2000 I don't see any lag bolts or anything else attaching that stringer to the wall. The orange goop is fire blocker foam. It looks to only be attached at the header and into the concrete floor. If by cross lumber you mean the what the top of the stringers are attached to, those are joists.
    – tymish
    Mar 4 at 1:22

2 Answers 2

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It appears in the pics that the stringer is nailed from the bottom, and that would not be sufficient support to remove the post.

Of course, mechanically this has worked for decades because when weight is applied to the stairs, the stringer rotates, pivoting at the bottom, and exerting pressure against the joist, not pulling at it. This is much like a leaning ladder. The pivot at the bottom needs to be arrested to prevent sliding out. Now, instead of anchoring the bottom, the top is hung, making it more robust in the event of earthquakes, vibrations, and lumber deflections.

Measure the available depth of the joist availabe for fastening, and compare it to the support required by joist hangers available to you.

I suspect the support does not suffice, and you can remediate this with a ledger, or a hanging header. The latter is best but probably very difficult to retrofit in your case.

Attach a ledger to the bottom of the joist to give it more depth support for the stringer. Fasten with framing screws from under (do not use "construction screws" or nails), and additionally fasten an "angle tie" around joist & ledger. Of course, place angle ties not where the stringer hangers go.

Trim the stringer as needed to provide support with a stringer hanger, by cutting off the triangular portion underneath the joist.

For hangers & ties use hanger nails (#10 1in) or framing screws and not construction screws.

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  • Thanks for the great explanation. I'll think about whether this is worth it or if leaving the support is OK. Looking at the pics, do the two 2 x 4 studs serve any support purpose? I know one was added (shortest) by me for blocking and looks like the other one was too when the closet wall was put up. Just having the two bigger posts i think i can deal with since I'm going to use that space for storage. In face there was another post under the stringer against the wall but it wasn't well secured to the floor so when i removed the plywood door it just kind of came off.
    – tymish
    Mar 4 at 15:38
  • @tymish those studs are for backing
    – P2000
    Mar 5 at 1:15
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With an old house, who knows what kind of strange cuts, holes, etc. have weakened or even severed load paths. Removing stuff like your studs makes me nervous because simple nonbearing studs can transition into critical supports if enough damage has been done elsewhere.

The connection between the stair stringers and the header at the top is necessary context. Before cutting anything loose, I would double check the load path from the stair stringers into the upper header. Also take a look at any connections holding the header up if the header isn't a main beam or load bearing wall.

The center stringer would get designed for twice the weight as the outer ones, so the stringers themselves are probably fine. The tallest post could be noticeably stiffening the upper floor, though.

That tallest post is what makes me nervous. Instead of the stair stringer's weight going into a header in that neighborhood, under enough damage the roles could reverse with the stair stringer holding up the header. Obviously the stair stringer would no longer be able to do that after you've removed those studs.

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