Substantial completion is a construction milestone when a building or project is sufficiently complete to be used for its intended purpose, even if minor deficiencies remain. At substantial completion, owners typically take possession and begin using the facility, contractors' major work is finished, and the warranty period begins. A punch list of remaining deficiencies is created for the contractor to complete. Substantial completion triggers important contractual events including release of most holdback funds, transfer of risk and insurance responsibilities, and start of warranty periods. Determining substantial completion involves inspection by architects or engineers who certify the project meets this standard. Municipalities require substantial completion certificates before occupying new facilities.