How to approach the assessment of an existing building

Assessing the safety of an existing building needs a very different mindset from designing a new building. This article discusses how to approach the assessment and some of the key questions which need to be answered, such as the extent to which we can rely on past performance and what margin of safety is acceptable. The article does not claim to have all the answers, but it is hoped these can be covered in forthcoming guidance from the Institution of Structural Engineers.