I'm building a small development with a shared basement for 2 units. I have a fixed price ABIC contract with the builder which includes construction of a basement. I have a building permit and construction had commenced its first small stage. The builder wanted the engineer to clarify a few issues - mostly around head room in the basement. The engineering firm has since realised they have made a mistake and the design cannot be constructed. Instead, they have come back with a new design that has more steel, more concrete and is a lot more complex. The builder's subcontractors now want an extra $150,000 to cover the variation! What is my legal position on this against the engineer? I've paid a 5 figure sum to the engineer for the dodgy drawings already. I wouldn't have proceeded with the project had I known the original design was incorrect.