In my plan I need most of the foundation to be a monolithic slab except in areas where there are pipes such as the bathroom. I am trying to figure out how to cut a hole in a foundation that I have generated in CA with the foundation tool, but when I try the "slab hole with footing" and the "Hole in floor platform" tools I get errors. "could not create hole in floor platform" and "a slab hole must be placed inside a slab".
To elaborate on the foundation, it will be piers 4ft into the ground then a normal monolithic slab and footings will be poured on top of the piers. The footings and slab will sit about 24" above the existing terrain where the piers tops also are. The soil cap will be course gravel and basecourse on which the slab will be poured. The bathrooms and other rooms with piping will be to the outside of the building and there will be a crawlspace below those areas to service pipes.
I am hoping someone has experience with this and can help me. I've scoured the forums and spent hours in CA to no avail!