81-21 - Floor Area Ratio Regulations LAST AMENDED 8/9/2017 The #floor area ratio# regulations of the underlying districts are modified in accordance with the provisions of Section 81-21, inclusive, or Section 81-241 (Maximum floor area ratios for a residential building or the residential portion of a mixed building). However, the provisions of Section 81-21, inclusive, shall not apply to #non-residential buildings# or #mixed buildings# in the East Midtown Subdistrict, where the special #floor area# provisions of Sections 81-63 or 81-64 shall apply.