Before you jump headlong into any substantial building project, it is important that you and your builder agree to several key points upfront. Items such as budgeting, project scheduling, fees and the parameters around up-charges or upgrades should be clearly agreed upon prior to the start of your project. What you need is a Builder’s Contract.
If you are going to be financing your new home or renovation, this contract will likely be required by your lender. Even if it is not, it is an important document to help protect both parties’ financial interests and will help head off any common misunderstandings.