Help with combining apts

I sure could use some help with a floor-through combination (aka duplex). About 12 years ago I purchase 2 apts, each about 1,100 sq ft and had them combined. They were mirror images and the combination was pretty straightforward -- keep the 4 bedroom, make a little office out of one of the kitchens, expand and open part of the wall to the other kitchen, and leave a large area for dining and... [more]

I sure could use some help with a floor-through combination (aka duplex). About 12 years ago I purchase 2 apts, each about 1,100 sq ft and had them combined. They were mirror images and the combination was pretty straightforward -- keep the 4 bedroom, make a little office out of one of the kitchens, expand and open part of the wall to the other kitchen, and leave a large area for dining and living. I just went into contract to purchase the apartment underneath one half of what I now have (i.e., one of the original two apts I combined). I'm having a very difficult time finding the space and location for the stairs. I wanted to put a switchback ("U" shaped) staircase in the little office created -- it's about 92" x 82". I had my architect bring a structural engineer who said he's 95% certain I can't put the stairs where I want them because the cut needed in the floor will be up against a column. The building is 20 stories tall and the floors are concrete slab with rebar supporting and into the columns. The building was built in 1960 but the original structural plans are non-existent, so we can't verify this. Then he said that wherever we make the cut, we will need to weld an iron frame around the hole to make up for the decrease in integrity of the concrete floor, and that will take up between 12 and 18", creating a need to make the hole that much larger. I asked about stair width and was told 36" is the minimum, but a spiral is okay. When I said that spirals are much narrower, I couldn't get an explanation. I'm feeling quite stuck. Does anyone know about cutting a hole near a support column for concrete slab floors? Anyone know how wide a duplex staircase must be where there is a means of egress on each floor (the original apt door)? Anyone have any other suggestions? Thank you, Joseph [less]