In M1-5B Districts, the requirements of Section 42-14 (Use Group 17), paragraphs D.(1)(b), (c), and (d), may be modified by authorization of the City Planning Commission, provided that:

(a)        such non-residential building is either a landmark or lies within a Historic District designated by the Landmarks Preservation Commission;

(b)        any alterations to the subject building required in connection with such conversion to joint living-work quarters for artists have received a Certificate of Appropriateness or other permit from the Landmarks Preservation Commission; and

(c)        a program has been established for continuing maintenance that will result in the preservation of the subject building or buildings as evidenced by a report from the Landmarks Preservation Commission.

In order to grant an authorization the City Planning Commission shall find that such modification of use requirements shall have minimal adverse effects on the conforming uses located within the building and in the surrounding area.

The City Planning Commission may prescribe appropriate additional conditions and safeguards in order to enhance the character of the subject building and to minimize adverse effects on the character of the surrounding area.