If the answer is "consult a professional" I definitely will, but want some confirmation that it should be possible.
Doing a basement reno to add an office space in the area around the basement stairs. There is a wall here which at first glance didn't look structural but...
3 LVLs run parallel to the upper half of the stair run. One on the far side that runs between two steel beams, one above the end of the lower stair stringer that runs between the two beams, and this one in the middle which lands on this framed wall. There is no beam in the corner, just a 2x4 at the end with a 2x4 turned 90 to make finishing easier. The lack of a doubled 2x is making me think this wall is holding more than I originally thought. I could easily double up on the beam there, with plywood in the middle and glue/screw it all together but seems like it may be over kill.
More pics
Detailed framing at the floor at the corner below the stair end of the beam
Large spacers between beam and wall
Framing at beam end corner
Lvl details
What's the hive think? I can reinforce the corner here easily and delete the rest of the wall? Reinforce header? The framing is pretty rough in there so not sure how it was holding itself up before the wall was there (upper stair stringer lands on a header between this beam and the next one back).
Help? 
I wouldn't have an issue removing the walls around the stairs. The LVLs are carrying the stairs. The 2x4 don't look to have any load on them.
Toyman! said:
I wouldn't have an issue removing the walls around the stairs. The LVLs are carrying the stairs. The 2x4 don't look to have any load on them.
X2 But I was in a Holiday Inn last night. ;-)
Those walls are adding stiffness to the stair stringers. You can remove them but I would place a vertical 2x4 under each diagonal stringer at about the midpoint location with another one next to it attached to the inside of the stringer and attached to the slab with some angle pieces.
Like this:
Those walls dont look like they do much.
Agree with adding bracing under the stairs or maybe a small half-wall (box in the lower section, small storage area?) to keep the stair stringers nice and tight.
Ok good. I was going to be rid of the right three and keep the left two open and the two t'd in the corner. I think that gives me plenty of room and I can add some storage cubbies in the space left.
I'm having trouble understanding how these stairs are built. Could you take a close up photo of the underside of the stairs. I have never seen anything like how the stair risers and treads are located at the bottom of the stair stringers. I might be taking back everything I said previously.
It definitely looks like prefab stairs.
Well, that is amazingly different. And fairly modern. I don't know what to say about removing the two side stud walls. Is there an lvl beam supporting the far side of the stair opening floor? If so you could probably still remove the side walls. I've never seen anything like that. I wouldn't want to carry a piano down those steps.
If I understand you, yes. There is another lvl that runs parallel to the far side of the stair. The only difference is that it goes further and sits on a steel beam instead of ending on the stud wall.
If its not obvious its a stair with landing and 90deg "left" turn as you are coming down. The landing is just 2x6? Framing to the studs and I dont need to mess with that at all.
The top of the stairs lands to another lvl that runs between the parallel ones attached with joist hangars.
Thining worst case I can support that with lumber to remove the wall and use a structural header on the larger opening. But will double check the span tables for that lvl first.
Below is a typical stair detail. It relies on a 2x4 kicker glued (PL 400) and screwed to the floor (in this case, the landing) to prevent the stair stringers (jacks) from sliding out, acting as a pivot and thus pinning the top of the stringers to the header at the top of the stairs. This is all that is required to hold the stairs up and in place and no other attachments are needed. Think open staircase.
The as-built photos show a large gap between the stair stringer and the header. I don't know how the bottom of the stringers are attached to the landing, but the only thing holding up the stringers are the nails attaching the stingers to the lower studs. You would need to add 2x blocking between the stair stringer and the header at the top of the stairs and also add blocking to the bottom of the stringers to pin them to the landing.
I think there is a 2x between the lvl and stair stringer. Will check that and how the stairs mount to thr landing.
SV reX
MegaDork
3/6/24 9:42 a.m.
It ain't gonna fall.
Don't worry about the LVL not being doubled. The only load it is carrying is half of the upper landing. The LVLs are designed for your longest span. If it bothers you, nail a 2x10 to the LVL.
Those are pretty standard prefab stairs. They hang on a nosing at the top, but should have a 2x block behind them as well. The wedges lock the treads and risers tightly in place, and the risers are secured to the rear of the tread at the bottom edge. Each of them act like a spine spanning the stringers.
Adding a couple post or knee wall under the stairs wouldn't hurt.
Hard to see but def a 2x4 between the lvl and stairs.
The stair bottom just sits on the landing. Anchoring the last riser and stringers to a 2x and fastening to the landing prob wouldn't hurt either.
In reply to Paul_VR6 (Forum Supporter) :
I'm trying to figure out where the stringer ends, at the top of the side wall or up at the upper floor sheathing. Any blocking has to be located for the stringer to push against. For the bottom of the stringers, add some angle brackets secured with #12 screws.
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In reply to Paul_VR6 (Forum Supporter) :
No, I'm not worried about the LVL.
The only thing I can find on the internet is this diagram of a "Housed Stringer Stairway". As long as the top of the stringers are leaning on the beam in someway, I have no issues with removing the walls.
I forgot to finish my load force diagram of a stair stringer so here it is.
The stringer stops short of the lvl by 1.5" but the top riser looks attached to the 2x. The stringers are nailed to the parallel lvls at the top as well.
Double checked the span tables and I am convinced I am good. I will update if anything stupid happens.
