Lay down 6 mil vapor barrierConcrete will almost never be perfectly dry so those extra layers of protection will keep your LV dry.

Plus, much of that "wealth" vaporizes with a dip in the market.Are the investors saying veterans or new since last recession?

@Vu Nguyen putting living area, which includes kitchen plumbing, in a garage will probably require cutting through the slab, trenching for plumbing, new concrete (including potential rebar doweling, vapor barriers, gravel, insulation, etc).

Vapor barrier.

Once you get into framing, there's a lot of things to know about vapor barriers, ground contact lumber, mold-resistant materials, etc.In my opinion, this isn't a DIY type of project unless you're a licensed contractor.

My "velvet glove" approach would be to light-heartedly tell them it's getting too loud outside and it is time to buy a vaporizer.

Concrete is the easy part.  2 x 2 spacing with 1/2 inch rod; 6 inches thick walls/sides; vapor barrier as needed.   

By building the floor up you can resolve the vapor barrier that’s required.  

A cabin next door to one of our nicer Cabins burned to the ground and vaporized one of our retainer walls, but no other mentionable damage other than that.

Yes, in power outages, she would not work, but when they kick on, it pumps it all out in minutes, and I just have a dirt crawlspace with vapor barrier so some water is less risk for me....If you have one of uncertain age, actually I might have a back up ready (not just for power outs) because you have to call the plumber, who may or may not have the one you want and may mark it way up.