Regardless of the size or type of a residential property, various kinds of maintenance must be performed, including general upkeep, emergency repairs, and special inspections (such as may be directed by an insurance company). But of particular importance for preserving buildings, equipment, and the grounds is preventive (or preventative) maintenance. All residential buildings require some form of maintenance to allow for their continuous use and safe operating conditions. Preventive maintenance is a form of proactive maintenance that can prolong service life expectancies and prevent equipment failure, when implemented appropriately. PM strategies also promote a reduction in overall maintenance costs, whereas reactive maintenance is typically associated with unplanned downtime and high expenditures for repair or replacement. Most residential systems have more in common than not, including their common critical assets, such as plumbing, electrical, and mechanical equipment. However, certain building types have unique maintenance considerations. Some PM programs employ a team of full- or part-time personnel that takes care of a property. Other programs call for hiring a residential property inspector to address the inspection portion of the maintenance program.