Can you add a screen/sun room and deck to a slab on grade?
...porch on the same slab, you just need to be sure to insulate between the heated and unheated portions. This is not the easiest thing to accomplish with a hand made slab but a company that supplies prefab slab on grade kits (Legalett) can easily provide that, see more here –
Slab-on-Grade Raft Foundation Insulation Det...