Building a pool is considered to be a major project and will, therefore, need a contract. To get a proper estimate of your project, you should take into consideration at least three or more estimates from different pool companies in Fairfax so you can get a better understanding of how the pricing works in your location. Pool contractors Fairfax usually place their bid that includes the total estimate of the project cost. They are not charged by the hour but by the project. To compute their expected earnings from the project, they get estimates from all their material suppliers and subcontractors to arrive at the total cost, and then they will divide it by a certain percentage. That certain amount equivalent to the percentage will be their project fee. If they are planning to propose a fixed price contract to you, they will add their project fee to the estimated total cost, and that will be the estimated overall expense of your project.