6. In these Regulations—

"floor area" in relation to a building means the area bounded by the inner finished surfaces of the enclosing walls, or, on any side where there is no enclosing wall, by the outermost edge of the floor on that side and in calculating the area of a building or part of a building there shall be included in such area the space occupied by any walls, shafts, ducts or structure within the area being measured;

"height of a building" (or of part of a building which is completely separated throughout, both below and above ground, by a compartment wall or compartment walls in the same continuous vertical plane) means the height of such building or part measured from the mean level) of the ground adjoining the outside of the external wall of the building to the level of halt the vertical height of the root of the building or part, or to the top of the walls or of the parapet (if any), whichever is the higher.