The basement slab in our 150 year old house has seen better days. It
has settled with the center about 7 inches lower than the
corners. Also there are cracks and many "rough" spots.

I would like to refinish the surface for a basement workshop and am
considering several options:
1. Add a new cement topcoat to the surface to cover cracks and rough
spots and partially level the floor (I don't expect to be able to


I'd want to know why you've got 7" of subsidence under the basement
floor, before making any suggestions. Of course, if you break up
and remove the existing slab, you'll be able to see what's going
on, and fix it. And put insulation under the new slab, too. Of
course,
there's a small but real chance that the existing slab is all that's
keeping soil pressure from shoving your foundation-walls in..

--Goedjn