The characteristics of PTFE sliding joints when used to separate secondary components from the main structure of a building are described. Their use enables damping of earthquake and wind motions to be obtained within the normal elastic range of the structure, and beyond, by virtue of the frictional forces generated, while temperature movements are at the same time accommodated. In addition a positive fixing is obtained which is a useful alternative to the hung-type of fixing which is at present recommended where separation is required. Further testing is needed to obtain more friction data on filled PTFE materials and suitable joints need to be developed.