The useful life of an appraisal varies with market conditions and property type. A Bank may use an existing appraisal to support a subsequent transaction if the Bank documents that the existing value estimate remains valid. Factors which could impact the value include the passage of time; the volatility of the local market; the availability of financing; the inventory of competing properties; improvements to, or lack of maintenance of, the subject property or competing surrounding properties; changes in zoning; or environmental contamination.