Fire resistance requirements for portal frames in single storey buildings

Frequently, the provisions of Section 4 do not require the portal frames of a single storey building to have fire resistance except where the column members of those frames are within, or support, an external wall, which under paragraph 5.2, is required to have fire resistance. Where this occurs both the column and rafter members should have fire resistance, as the moment-resisting connections mean the portal frame acts as a single element. However, in the case of a steel portal frame which has been designed in accordance with the method set out in Fire and steel construction: Single Storey Steel Framed Buildings in Fire Boundary Conditions, only those members within or supporting an external wall requiring fire resistance, need have fire resistance.