The Raft itself or Slab on grade on top of it? 1

[Robert-32]

What is the common practice for a basement floor of a storage reinforced concrete building, is it to have the same raft as the basement floor, or to add a finishing layer slab on grade on top of it?

 

[KootK]

I've seen it done both ways. For a non-storage occupancy, my preference is for an independent slab on grade however. I feel that's easier to finish robustly. That said, if the owner would be amenable to a floor finish that is a little rough, and potentially unlevel, perhaps using the raft as the finish floor would be an acceptable cost savings.

Another thing to consider, even in a storage occupancy, is the need for services to run below the floor slab. This is a pretty easy thing to do with an independent slab on grade. It requires a lot more coordination, and acceptance of limited future options, when the services must be embedded into the raft slab.

 

[Robert-32]

Many thanks Kootk. If I was answering this question myself, my answer would be exactly the same. I just wanted to confirm my point of view. Thanks again.