A safe laboratory can be designed and built only if people skilled in those tasks are involved. The laboratory designer must have experience in positioning equipment, laying out traffic patterns, and locating safety equipment so that these all work together to provide a safe environment for the workers. A lab user or lab supervisor makes the decision and can describe what must be included in the lab, and what will be done there, but the architectural features that contribute to a safe design are usually missing from the first concept. A user would set out the requirements for the laboratory, a designer would determine the optimum size and shape for the lab, and the chief executive would authorize the funds necessary to build it. The overriding feature of design phase is detail, detail, detail; all parties to the design are involved in endless checking and rechecking of drawings, specifications, conditions, and contracts.