In the case of damage or destruction of less than 75 percent of the total floor area of a non-conforming building containing three or more dwelling units in an M1-1D, M1-2D, M1-3D, M1-4D or M1-5D District, such building may be repaired or reconstructed, and its residential use continued, subject to the following regulations:

(a)        there shall be no increase in the number of dwelling units in the building beyond the lawful number in existence prior to such damage and destruction; and

(b)        there shall be no increase to the pre-existing amount of floor area except as expressly provided in Section 52-46 (Conforming and Non-conforming Residential Uses in M1-1D Through M1-5D Districts).

Enlargements in excess of those permitted, pursuant to paragraph (b) of this Section, and enlargements that create additional dwelling units, may be permitted by authorization of the City Planning Commission pursuant to the regulations of Section 42-321 (Residential uses in M1-1D through M1-5D Districts).