I'm slowly working on bath remodel. A tile contractor demo-ed a sunken tile roman tub w steps that was in a slab foundation. He filled in the hole w concrete, and attached a new drain to the old to bring it up to floor level?? Is that ok, he did not use rebar? He used a similar technique on my shower, but cut out the old cast iron drain because it was too narrow. I thought he would go down to the ptrap, he says that's not necessary? What do you think?