• Depreciation (property) is a measure of the loss of the possibility of using property that has not been physically damaged, but is less salable due to the presence of a known defect in it. For example, a building built with low-quality materials that has not yet been found to have any physical damage, but which will certainly appear over time, loses value. One of the purposes of excluding “impaired property” from general commercial liability (CGL) is to exclude coverage of impairment claims.