[Evans, Marv]

Nick. I'm no expert in the legalities, but I certainly would explore the potential for the original contractor shouldering at least part of the cost. First, you probably already know - Document, document, and document. If it were me, I might put together a letter/form of some kind and ask whoever gives you an opinion if they would answer the questions on paper and sign it. I expect lots may decline to become involved, but it could be more ammunition if/when the time comes. You could have the concrete tested and compare the results with what was represented to you in whatever paperwork you might have from when you purchased the house. Others with lots more & better advice will likely chime in.