When doing a custom house there are many variations and permutations to the builder"s contract. I would strongly recommend that you obtain a real estate attorney who specializes in new construction, single family homes. Keep in mind that this type of attorney may charge by the hour but I have found there is a definite need for an attorney with major new construction custom housing experience and in the long run it may prove most economical.
Note, in the contract there should be checks and balances for cost over runs as well as procedures for drawing money from the escrow account. In addition, there should be written material in the contract pertaining to cost for changes and a detailed description of all product and appliance brand names, including model number.
I have outlined just a few of the things that should be in this type of contract. In summation, only after
a good attorney has reviewed the contact and made modifications to the contract should you hand over money to the builder.