A.5. In determining the height of the eaves for the purposes of paragraphs A.1(c) and A.1(d)—
(a)the determination is to be made by reference to the point where the external walls of the dwellinghouse would, if projected upwards, meet the lowest point of the upper surface of the roof; but
(b)no account is to be taken of any parapet wall or any part of the roof slope which overhangs the external walls of the dwellinghouse; and
(c)where the existing dwellinghouse has eaves at differing heights, a determination for the purposes of paragraph A.1(c) is to be made by reference to the eaves of the part of the existing dwellinghouse from which the enlarged, improved or altered part of the dwellinghouse extends.