The room in question on the second floor (where the star is). The dotted lines in the plan show the floor below.

Orientation shot -- My friend (redacted) is standing in the southwest corner

SW

My redacted friend is still in the southwest corner, camera looking northwest.

NW

SW

This is the floor plan of the floor above. One concern we have is a cast iron clawfoot tub (900-1000 lbs or so once loaded with water and one or more large renters). It’d go in the northwest corner of that bathroom. (The north wall of that bathroom is about 60” whereas the tub is just 30” wide.

NE SE

Orientation shot of east wall. (This picture may not go all the way to the NE and SE corners.) The total E-W span is 9.5’.

Soilstack

There are two layers of framing: floor joists, and ceiling joists. Most floor joists terminate in a horizontal mid-span single “header,” attached with clips.

NW

This “header” is 2” (or even a bit wider) x 7.5” (real dimensions) but notched down to 4”. The floor joists are 2 x 5.5” (real dimensions). The ceiling joists are in hangers. They’re nominal 2 x6s but at times ripped down to less height. That might not matter since they’re not supporting much weight (at least currently).

There is a 1” gap between the header and the new ceiling joists.

Close up of gap and the wood of the header and floor joists.

Another look at the header / floor joist / relationship (still looking west). The floorabove is 1” x 5” (actual size) planking.

I didn’t take enough photos of the “header” from the west. It’s maybe 2-3’ from the wall. There are tail joists that attach to it. In some cases those appear to rest on the partition wall (in one case on a 4x6’ post). In some cases, as here, they rest on nothing and are held up by the floor planks. In some places (pictured next) they’re sistered to the adjacent room’s floor joists. The floor above is a bit unlevel, with the lowest point right to the west of this header. They lose about 1” over maybe 30” distance, then regain about ½ of that at the header. It doesn’t feel loose. It feels more like maybe the tail joists were nailed in at an angle.

Header

North

West

Not supported.Held up bysubfloorplanks?

Ceiling joist running below the header.

Here the tail joist is sistered to the floor joists that continue in the next room.

West

The header

Floor joists from room to the west, clipped where possible to posts at partition wall

West

Floor joist from neighboring room

Here is that sistering again. The floor of the room above is slanting down as you head east until you get to the header, just off-screen to the right.

Here’s a pic of the third floor bathroom looking north. These two drains are sort of visible in some of the photos from below. The low point is a north-south line about where the mallet head is. It doesn’t run all the way south, just about 24” south from that point. The bathtub is going to go in the upper left corner here.

NW

How is the header supported? Held up by the tail joists, I’d guess.Here is its north end. This is just across the hallway to the north of the room.

Header

It terminates here at a floor joist for the third bedroom, attached with nails

Header

Floor joist in the next room to the north

… two relatively big but kinda rusty-looking nails

Floor joist in next BR looking south

FYI, here is the basement floor plan. There are footers and a partition wall underneath part of the west wall of the room in question. There is also a partition near its north wall, though no footer there.

N