The effects of variations in the ISO 9705 Room/Corner Test equipment and product properties are discussed. Previous experimental results are reviewed and some new results from the EUREFIC fire research programme are reported. The effects considered include the room dimensions, the burner size, the heat output of the burner and the stand‐off distance of the burner. The error in the measured peak rate of heat release caused by the finite response time of the oxygen consumption calorimeter due to mixing of the exhaust gases is analyzed in detail. The effect of material properties determined with the cone calorimeter are evaluated by employing models simulating the Room/Corner Test.