ISO/CD TS 21721.3:2025

This technical specification provides guidance on the calculation of the fire resistance performance of asymmetrical partitions and/or vertical membranes using existing fire test evidence. The fire resistance performance of asymmetrical partitions and /or vertical membranes is established on the basis of existing fire test evidence for asymmetrical partitions and /or vertical membranes to ISO 834-1 The asymmetric partitions are constructions that comprise of one, two, three or four layers of gypsum plaster boards which are installed against C-profile steel studs. The principles of the calculation methodology can be applied to other types of board materials used in partition systems and to other heating regimes.