Timber-frame construction is characterized by mortice-and tenon joints and an absence of earth-fast posts; it can be broken down into several distinct categories. Charles discusses the variations used from the 13th to the 16th centuries. The author discusses the preservation of timber-frame buildings, including surveys, documentary drawings, and repair procedures in light of the requirements of the Historic Buildings Council (England) and other British government bodies. His personal philosophy is that, except in museums, there is no purpose in trying to reconstruct the original design of a building down to the last detail.