This report extends the step-by-step method of thermal analysis of unprotected steel, to a multi mass system and includes radiant heat transfer between elements. The analysis was applied to i) partial protection of a beam and to ii) a light-gauge radiation shield around a steel beam. Both the partial protection of the bottom flange, and the light-gauge steel radiation shield improved performance but did not give useful protection against a realistic fire in a gypsum plasterboard lined fire compartment. The report also formulates a method of thermal analysis for gypsum plasterboard ceilings. This analysis was applied to a gypsum plasterboard ceiling giving protection to a steel beam within the ceiling space. Gypsum plasterboard ceilings were found to give useful protection to steelwork in the ceiling space. The analysis method can be implemented using a spread-sheet analysis, or by using a simplified approach based on the ‘equal area concept’. Three compartment experimental tests, along with previous furnace data, validates the analysis. The report also compares the time-temperature curves of the three compartment experimental tests with the Eurocode (and modified Eurocode) Parametric design fires.