Legal Question in Construction Law in California

What you attempted to do was what is known in construction law as a "design-build" contract. If it's any consolation, you are in good company with many of my clients in having that turn into a problem, and I'm not talking home remodels. I'm talking about such clients as the San Francisco Sherriff who wound up in litigation over the design-build of their new high security jail, and the contractor that built the Sonoma County waste water treatment plant.

What the contractor was bound to do for what price is going to turn on a close analysis of the contract documents. It's not something that can be done in this forum.

The answer to your question depends on the contracts, the drawings/blue prints, and facts not provided in your question; so it is not possible to give a definitive answer without seeing these documents and knowing those facts That being said, if it is clear from the wording of the contract that the contractor agreed to perform to certain specifications contained in (or attached to) the contract, then the contractor may only be bound to perform to those specifications and not specifications that were changed after he signed. If the above is not clear, then it is open to interpretation as to what was agreed to. Generally, courts will not hold a contractor to a bid if the plans changed (through no fault of the contractor) after the bid to the extent that the original bid is no longer financially practical for the contractor.