This guide reviews and analyses the systems and techniques currently available to insulate externally the walls of most types of buildings. Since the major energy saving interest in the United Kingdom is concerned with up-grading dwellings and public sector buildings, such as schools and hospitals, those are the areas on which attention will be focussed. However, recently domestic housing has increasingly been examined as to the production of Thermal Performance Certificates, together with the aspect of sustainabilty of building material supplies. Also included are detailed drawings for all common situations where detailed consideration must be given to the project to ensure a professional installation.