Article 3.　As to houses as designated in Art. 6 of the Supplementary Provisions of the Law, the provisions of Art. 3 and Art. 5 of the Law shall not apply until December 31, 1951, and the provision of Art. 16 of the Law shall not apply until March 31, 1950; provided that in respect to houses which are extended after the enforcement of the Law, these provisions shall apply on and after the day or which the extention was made.