“ (16) For the purpose of this Group, the construction of a building does not include – (a) the conversion, reconstruction or alteration of an existing building; or … (b) any enlargement of, or extension to, an existing building except to the extent the enlargement or extension creates an additional dwelling or dwellings … ”
“ (18) A building only ceases to be an existing building when: (a) demolished completely to ground level; or (b) the part remaining above ground level consists of no more than a single façade … the retention of which is a condition or requirement of statutory planning consent or similar permission. ”
“ The face or front of a building towards a street or other open place, esp. the principal front. Also attrib. or as adj. , of an architectural design concerned with elegance, etc., in the façade of a building alone. ”