Please note that this is a scanned copy of a paper originally published in 1996, so the text is not as clear as in documents created as pdf files. This report describes work carried out on behalf of the Building Regulations Directorate of the Department of the Environment. Five years of experiments were carried out at the Fire Research Station to examine thermal spill plumes under different conditions in order to validate and determine the limitations of existing spill plume calculation methods. A scanned copy of the library archive copy. 54 pages.