The answer to this one starts at the bottom—your foundation. The most foolproof way to control the largest variable in construction is to get a structural engineer to design it.
But an engineer can’t do that until they have a final set of plans from your architect. By having the soil analyzed, we can get a sense for a ballpark figure of what your foundation is going to cost, but to truly have control of this huge variable (foundations can cost from $10,000 to $100,000) we need a set of foundation plans that we can get bid out and get under contract. This is just one of many reasons, a final set of plans from your architect is so important.