This Technical Report has been prepared in order to review whether the current ISO furnace-based fire resistance testing methods remain appropriate for establishing the performance of elements of structure when exposed to fully developed fire conditions in the context of a fire safety engineered strategy for a building. It identifies whether there is a difference between the data produced and the data required. Where there is, it reviews whether the test methods can be easily adapted to improve either the relevance of the test, or the output data, to make it more suitable for use in fire engineering applications. This Technical Report reviews the mechanisms and routes of fire spread and identifies the criteria used for these tests to aid simple comparison and compares them with the conditions that can lead to fire spread or a loss of tenability for people in reality.