BS CP 3 CHAPTER IV-1:1962

These recommendations apply to blocks of flats or maisonnettes (i.e. dwellings on more than one floor) having any floor more than 80 ft. above the ground. This height has been selected as a basis for the recommendations because dwellings above that height are beyond the reach of rescue or fire fighting from a mobile ladder outside the building. The selection of this height, however, does not imply that the possibility of rescue below 80 ft will necessarily be adopted as a factor in the recommendations yet to be made for the planning and construction of lower buildings.