This Standard provides a guideline and methodology for assessing the condition and performance of existing building envelope systems and components, and identifying problematic and dysfunctional elements. As the adaptive reuse, rehabilitation, and improvement of existing buildings have assumed a more prominent role in meeting national needs, the ability to accurately assess the conditions of a building is imperative. The condition of the building envelope is most important since failures can result in safety and health problems, as well as structural damage. Proper evaluation of the building envelope is often the first step toward stabilization and rehabilitation of the building. This Standard is a compilation of basic information, procedures, and references, and will be an asset to the investigator developing a logical approach to the assessment of the building envelope in order to focus on fundamental defects rather than outward symptoms.