A Detailed Engineering Assessment (DEA) is a detailed structural engineering investigation and reporting of a building structure. A DEA is necessary when there is insufficient information and documentation on the building structure to determine the safety of the structure. Intrusive or destructive assessment is expected to be used during this detailed assessment. This means that partial removal or destruction of some structural elements is necessary, for example taking a core out of a concrete column, removing soil for lab testing or removing finishes to see hidden/covered details. This guidance notes describes how to carry out Detailed Engineering Assessment (DEA).