Sure this is going to catch a few unawares.   new Part O (overheating) states: Any guarding to be sized to prevent the passage of a 100mm sphere, to be 1.1m high from floor level, to be not easily climbable and to be capable of resisting at least the horizontal force given in BS 6180:2011.   Park K states: "section 3.1 At Opening windows except roof windows in loft extensions, see approved document B1" max height 800mm   Park B states "section 2.10 bottom of op