A cost code is a number that categorizes every construction cost by the type of work it represents. RainFire Builders uses the CSI MasterFormat system — a 50-division numbering standard covering all construction work. Common residential cost codes include Division 01 (General Requirements — supervision, temporary facilities), Division 03 (Concrete — foundation, flatwork), Division 06 (Wood & Framing), Division 07 (Thermal & Moisture — insulation, roofing), Division 08 (Openings — windows, doors), Division 09 (Finishes — drywall, flooring, painting), Division 22 (Plumbing), Division 23 (HVAC), and Division 26 (Electrical). When a cost is recorded, it’s assigned to the appropriate division — so the job cost report shows budget versus actual for each trade scope separately, making it immediately visible which areas are tracking on budget and which are not.