11In this Schedule—
" building " includes part of a building ;
" owner ", in relation to a building, means the person entitled to possession of the building ; and
" relevant hereditament " and " relevant period of vacancy " have the same meanings as in section 21 of this Act,
and references to a newly erected building or dwelling-house include references to a building or dwelling-house produced by the structural alteration of a building included in a relevant hereditament which by virtue of paragraph 6 of this Schedule has ceased or will cease to exist on the completion of the structural alteration and, in relation to a building or dwelling-house so produced, references to erection of a building shall be construed as references to the structural alteration producing it.