ABSTRACT
Our buildings are not as durable as they used to be and they demand much more of us if they are to remain useful. The more sophisticated we make them the more potentially defective they become. Different sub-systems of buildings age at different rates which affects our concept of durability. Usually the most seriously defective sub-systems are the building envelope and the engineering services and these should be considered and refurbished together. But the image of the building stock, and our most immediate benefit from it may reside in the more visible systems, and it may be these which determine how durable we want our buildings to be.
