Black magic. Bean counting. Guess work. Guestimates. Ask a group of engineers to describe construction cost estimating and that is what you are likely to hear. Not that they regard cost estimating as unimportant. They realize it is essential to all projects. But from their point of view, it is a mysterious process.
There is nothing esoteric, however, about cost estimating. It is an engineering discipline like any other, with its own rules and techniques, and a knowledge of these can be very helpful to those in other disciplines. Such knowledge can, for example, help designers, contractors, and building owners to determine whether an estimate adequately reflects their intentions and to understand how a change in design or construction can affect the schedule or total cost of a project. This can lead to consideration of appropriate alternatives and development of better quality, lower-cost projects.