64-614 - Process for establishing non-conforming uses LAST AMENDED 5/12/2021 For all #buildings# with #non-conforming# #uses# utilizing any of the provisions of this Section, the amount of pre-existing #non-conforming# #floor area# and pre-existing #non-compliances#, as applicable, shall be based either on construction documents for such #building# that were previously approved by the Department of Buildings at the time of construction, #enlargement#, or subsequent alteration, as applicable, of the #building# or, where an approved set of construction documents does not exist for such #building#, an as-built drawing set completed by a professional engineer or architect. The Department of Buildings may request additional information to substantiate proof of #non-conformances# and #non-compliances#, as applicable. Verification by the Department of Buildings of such documentation shall be a pre-condition prior to any demolition for reconstruction work, or alteration permit issued by the Department of Buildings for a #zoning lot# altering or reconstructing #buildings# with #non-conforming# #uses# and #non-compliances#, as applicable, pursuant to the provisions of this Section.