I'm working on designing a new house and trying to determine how thick the basement slab should be. This home will have poured basement walls over the footings, so the basement slab isn't bearing the weight of the house walls.
The International Residential Code (IRC) 2012 which applies in my area states that:
Concrete slab-on-ground floors shall [...] be a minimum 3.5 inches thick
I've found that most slabs are 3" to 4" thick, excluding the footings.
But I also know that the code is a minimum, and in some cases it makes sense to go beyond what code calls for. Is there any advantage to pouring a basement slab over 3.5" thick?