This chapter presents a survey of available numerical methods used in the thermal and structural analysis of buildings in fire. The problem of structural response of buildings to fire is normally broken down into two distinct parts. First, a thermal analysis is performed which considers heat transfer to and heat flow within the building elements. This is followed by a determination of the mechanical response of the heated elements and their interaction with the rest of the building. In the work described in this chapter no less than seven different thermal analysis programs and fourteen structural analysis models have been identified [1]. All of these programs are in common use and can be employed to provide data as supporting evidence for regulatory compliance. Little work has been previously presented by way of general validation for these methods. More commonly, programs are validated against specific and limited test data. In achieving a good correlation between theory and practice it has been observed that it is necessary to make a number of assumptions, often in an arbitrary and empirical manner. This often means that the accuracy of output is determined by a pre-knowledge of the result. Such methods have to be used with caution and understanding. The work described in this chapter discusses the theoretical background to the programs together with their strengths and weaknesses. Some comparative bench mark testing was also carried out.