Please note that this is a scanned copy of a paper originally published in 1988, so the text is not as clear as in documents created as pdf files, eg you may need to enlarge equations in small type. During a fire, heat can affect one side of a wall or floor leading to differential thermal expansion and bowing. Data from experimental and theoretical work can be used in the design of buildings to reduce the detrimental effect of thermal bowing in, for example, tall walls. 4 pages.