1(1)The carrying out of any of the following works, that is to say—N.I.
(a)the rebuilding, as often as occasion may require, of any building which was in existence at the date of the passing of this Act, or of any building which was in existence before that date but was destroyed or demolished within the period of five years ending with that date;
(b)the rebuilding, as often as occasion may require, of any building erected after the passing of this Act which was in existence at a material date;
(c)the rebuilding as often as occasion may require of any building destroyed or demolished by war damage, not being a building existing at the date of the passing of this Act;
(d)the making good of war damage sustained by any building;
so long as the cubic content of the building does not exceed the cubic content of the original building—
(i)(where the original building is a dwelling house)—by more than ten per cent. or seventeen hundred and fifty cubic feet, whichever is the greater;
(ii)(where the original building is not a dwelling house)—by more than ten per cent.
(2)Any reference in sub-paragraph (1) to the original building is a reference to the building which existed at a time before any rebuilding mentioned in that paragraph was first executed and not to the building resulting from the execution of any such rebuilding.