Nothing herein contained shall require any change in the plans, construction or intended use of a building, for which a building permit was issued prior to the effective date of Ordinance 2816 passed January 5, 1949, and the construction of which shall have been diligently prosecuted within six months of the date of such permit, and the ground story framework of which, including the second tier of beams, shall have been completed according to such plans as filed within two years from the date of the passage of Ordinance 2816 passed January 5, 1949. Nothing herein contained shall prevent the restoration of a wall declared unsafe by the Building Inspector.
(1955 Code. §1151.02)