You'll need to do the floors and paint.

But that number will vary by the quality of the upgrade, vinyl floors or expensive travertine tile, Formica counter tops or granite.

This scenario is usually only the case with mobile homes attached to land.Long story short is that you should fix the holes in the floors, holes in the walls, holes in the roof, fix the electric and plumbing if broken.

I plan on gutting the whole lower level (quad level house) but it has some kind of tile installed on the concrete floor.

The renovation included replacing all the windows, new central heat and air, replaced or refinished all the flooring, repainted everything, fixed lots of rotten wood and drywall and did a complete kitchen.

It needed everything; plumbing, electrical, HVAC, roof, windows, insulation, drywall, flooring, all new fixtures.I had to remove the entire second floor and rebuild it; 2 bedrooms and 1 bathroom.

There are multiple factors involved.One is that the opening through the floor will need to be enlarged.

Personally, I think the space used for the one beds would be better used as a single unit for that market. 10,000 usable sqft now but 12,000 added after putting in a floor

Maybe new floors.

if you put this off for too long you will be paying more in the long term by having to remove the existing and siding Exterior Siding(if you decided to go this way) - $8k+ depending on the house and local labor If you don't have the cash for the purchase, and you run into these expenses - and the repainting/flooring expenses that comes when people move out you are going to be barely scraping by.