New Reptile Room in basement - Looking for ideas

wow that's quite a gradient, and I'd be willing to bet it'd be similar with ours. Never thought of insulating the floor beyond putting down wood or something like that over the concrete. I suppose we could do what you suggested with the foam board and plywood and bypass having to dig up the existing concrete to put a drain in there. It would also make radiant floor heating easier to install... I like that idea

My room is even smaller than yours (13x16).

I heat with a gas fired space heater. I saw a big difference in my gas bill once I insulated the ceiling. Insulating my floor is what controlled the temps.

We have boas, beardeds and some hots.

I have shelves close to the ceiling where I take advantage of the 90 degree constant temp for my dubia roach colonies. At floor level, I keep the beardeds and the hots.(easier to access since they are all in front opening cages and my boas are in tubs.)

Plan, plan, plan and you won't be disappointed.