To supersede the requirements of Sentences 9.10.8.1.(1) and 9.10.21.1.(1), which would otherwise require a minimum 45 min fire-resistance rating, and permit a lower minimum fire-resistance rating, on the basis that this rating is considered adequate for construction camps.
To limit the probability of fire on one storey of a construction camp spreading to another storey during the time required for occupants to leave the space, which could lead to harm to persons on the other storey.