Removing staircase and filling in the hole

My old house has a 11 x 13.5 kitchen with a basement L-shaped staircase which is blocked off by two non-load-bearing walls and a door (see attached picture). This essentially removes about 50 sq. feet from usable space. My plan is to demolish the walls and the staircase and fill in the hole and then remodel the kitchen. The question is whether old discontinuous joists should be replaced, or can the hole be repaired some other way. To allow basement entry, the plan is to cut into the floor in a different location. It looks promising however there is an old water and gas lines in the way which will have to be moved a few inches. Overall it would be nice to hear some thoughts on the project, feasibility and ideas.
https://docs.google.com/drawings/d/1...it?usp=sharing
Thank you

 

Welcome to the forums! Why is there a door where there is no wall? If your drawing is somewhat to scale, I don't see a more viable place to put the staircase. You would lose the same amount of floor space, regardless. All the vertical framing below the staircase must remain intact for support of the joists and headers. You can use joist hangers and install new joists across the opening, the apply your plywood flooring in what ever thickness the old flooring is. Pictures help us quite a bit, although your drawing is also helpful.

 

Thanks for the reply. The plan is to use space in another room (closet actually) for basement staircase where it would make more sense. There is a partial wall where the door is (updated the drawing)

 

Just remember installing a new staircase isn't as simple as cutting a hole in the floor. The floor joists need to be altered in a manner that will still carry the load of the missing joists or cut joists [dependent on which direction they run]

 

Thanks, I will upload some pictures to show where the new stairs are planned, there is already a supporting beam in place. Nonetheless I plan to add another one just in case. My worry is that the new run may not be long enough before running into existing ductwork, but this can be removed/replaced.