Often, you will pay specified amounts at certain milestones in your contract. To avoid miscommunication and confusion, payments should be made at clearly defined intervals. Often, a contractor will request a deposit when you sign a contract. Any advance deposit should be roughly equivalent with the risk involved for the contractor. For example, if your contractor needs to special order materials before construction begins, you may be asked to cover some of the special order costs in the deposit.
Some states only allow a certain percentage of the entire project's cost for an advance deposit.
Check with your local building department for more information. If a contractor offers a written warranty, it should be referenced in the contract. The warranty should cover materials and workmanship. The length of the warranty period and any limitations should also be clearly stated. If a dispute between you and your contractor arises your contract should specify how the dispute will be resolved.