Now that he's broken through one of your basement walls and removed two feet of soil, it's a little late to be having second thoughts!! So it's labour only. Assuming this is a smallish house--say 2,000 sf or so, the price is low. But, for some parts of the country, I suppose, not absurd for a no-invoice deal. But, as you have described it, there may be a lot wrong with the way he's doing it! On a house I bought to renovate, I was presented with a similar situation. The previous owner had lowered the basement floor by about a foot by breaking the concrete floor up and and digging. Then he had laid a new wood floor directly on the soil! (The basement was totally finished when I bought the home, so I didn't realize what I was buying.) In lowering the floor, he had dug lower than the footings--in this case, bricks laid perpendicular to the brick foundation wall. Essentially, he undermined the house. (And since it was a semi-attached, he had partially undermined the adjoining home too.) A professional engineer designed the fix: a rebar reinforced retaining wall around the entire perimeter of the basement to provide lateral support to the footings. Since I was doing that, I also lowered the basement a bit further and put in new sewer lines. My concern on your home is that the excavation has undermined your footings too. He left a foot of undisturbed soil between his excavation and the walls. That's not adequate. Putting up stud walls to secure wall finishings is fine. None of this work was done with a building permit, I take it. Before you proceed any further, I strongly suggest you contact your local building officials or a qualified professional engineer to design this project properly. Don't be surprised if the municipal inspector puts a "stop work" order on it. It's only a bargain if it's done right!!

Where are you located? 2012 and current building codes prescribe insulation under slabs in building climate zones 4 and up. Climate zones 4 and 5 need R10 2' in around the perimeter while 5 and 6 call for R10 4'. We are in zone 4 and usually put R10 under the entire slab even with no radiant flooring. I much prefer spray foaming underslab than foam boards. It takes a good installer but you end up with a much stiffer insulation underfoot and better product. It sprays into and seals off the cavities of pre-cast concrete panels, edge of CMU or concrete, and any foam boards in thickened slab areas. Taping off foam boards and trying to seal off the perimeter is a labor intensive PIA. A good spray foam install acts as both insulation and soil gas barrier.

Jake- here’s the photo. Your last comments about how to correct did not show up in my feed before the plumber came back. Not sure what that was about except we had horrible internet service the last few days. I did ask to avoid elbow so there would not be a restriction beyond what the PEX already does coming from copper line. So I missed your point about that completely. I was just going from what I read on other forums. He’s added some pre-made supports inside the holes in the wood so the tube isn’t moving back and forth on the wood. And added some tape as well. We are able to get to this pretty easily from the back side of the wall just taking off sheetrock. The valve is installed correctly. And I have not corrected the wires yet on that box. There appears to be enough slack to fix in place. I Also need to check to see if I need a 2x4 below that wiring. Anybody know?

How about another idea - I built my custom house in San Antonio on a slab, and if I ever did it again I would pay whatever it takes to use pier and beam or a perimeter foundation instead, along with using a conditioned crawl space. We haven't had many slab issues, but they are always a PIA to fix. We have had two in-slab water pipe leaks that led to rerouting lines around the leaks. There has also been enough shift in the slab to put cracks in the original tile, and then small cracks again in the travertine that replaced it. The 2nd time they added underlayment that was supposed to prevent cracks, but it was not effective. Bruce