1The carrying out of any of the following works, that is to say—
(a)the rebuilding, as often as the person having the right to rebuild may desire, of any building which was in existence on the appointed day, or of any building which was in existence before that day but was destroyed or demolished after 7th January 1937, including the making good of war damage sustained by any such building;
(b)the rebuilding, as often as the person having the right to rebuild may desire, of any building erected after the appointed day which was in existence at a material date;
(c)the carrying out of works for the maintenance, improvement or other alteration of any building, being works which affect only the interior of the building, or which do not materially affect the external appearance of the building and (in either case) are works for making good war damage,
so long as (in the case of works falling within any of the preceding sub-paragraphs) the cubic content of the original building is not exceeded—
(i)in the case of a dwellinghouse, by more than one-tenth or 1,750 cubic feet, whichever is the greater ; and
(ii)in any other case, by more than one-tenth.
2The use as two or more separate dwellinghouses of any building which at a material date was used as a single dwellinghouse.