This spring's mega-project

[mikejurasw]

Hi everyone,...I'm not certain this is the exact forum for my question, but I'll start here.

I'm planning a basement re-do this spring. 86-ing the knotty pine, carpet tiles and ratty drop-ceiling for insulated drywall, can lights, a bathroom and leveled floor.
Unfortunately, this house is older, and has a poured concrete floor which slopes down from all sides to a central drain, with roughly 3 inches total slope from walls to an emergency floor drain. I will only be finishing about 2/3 of the space, so I don't have to gut and level the entire space.
I would like your input/expertise on two challenges:
1) I'm going to need to move the central drain about 3 feet, into the unfinished portion, so I can level and use this part of the floor while still keeping an emergency floor drain for the remaining unfinished and sloped part of the space. (This basement has no chronic water/flooding problems). What's the best way to do so, and to determine---before I start jack-hammering---where the pipes run?

2) I'm planning to drive in some tap-con markers and then level the larger slope close to the drain with bagged concrete mix, to about 1/2-inch before pouring liquid floor leveler to finish. This creates two issues: a) There will be a nearly 3-inch variation between the new floor and the old, at points. Of course it will all be nicely drywalled, etc, but is this weird? From "backstage" there will clearly be two different floors.

And...b) the last step of the (slightly wonky) staircase will be significantly shorter after the concrete is leveled...like, too short. What are my best options? Should I just plan to build a new staircase from scratch? Keep the stringers and re-format treads and risers once the floor is in? Get creative and do some sort of "L" landing at the bottom to change direction and throw visitors off the scent?
Any help will be appreciated!
Best,
Mike in Ohio

 

[Snoonyb]

I would have the drain X-Rayed so that you can then saw-cut for the relocation, as opposed to randomly breaking and hoping.

Depending upon the area to be leveled, I'd form the area with a curb and have slurry pumped.

For the ceiling you'll need to provide fire rated access for elec. "J" boxes and plumbing traps.

I think the landing would relieve you the necessity of a new staircase.

 

[mikejurasw]

Thanks, Snooby. BTW, I intended to attach some photos, but had trouble with tech on my end. Is the slurry you mentioned something like "Gypcrete"? Any idea how pricey that gets? Is it worth it to not have the nuisance of mixing and spreading my own?

I'll have no plumbing traps to worry about in this space, but probably some electrical junction boxes. How does one go about finishing a ceiling in drywall while providing access?

If I don't go with a landing at the bottom of the staircase, could I remove the bottom six treads and---once I know the floor is leveled and the stringers are trimmed, replace them, stealing 3/8" from each one? Is there a 'fudge factor' for stair height that I can get away with?

Thanks again!

 

[Snoonyb]

You'll need to determine if the method fits, economically, with the sq. footage of the area, as a yd. of concrete will fill an 80 sq. ft. area, 4" thick, and you can find out from local vendors, the economics of the supply.

There are fire rated access panels, in different sizes available, and there is also prudent placement of fixtures, which when removed, will allow access.

Altering the rise needs to remain consistent throughout stairway, without weakening the stringers.