NYC LL 92 and NYC LL 94 require projects involving the construction, addition, or replacement of a structural roof deck to install solar PV or a green roof on all usable roof space. This includes any new construction projects, vertical and horizontal extensions, and also projects with major modifications to an existing roof that requires a permit. Buildings that cannot accommodate a minimum of 4 kW solar PV or 200 sq. ft. of green roof may be eligible for an exemption. Buildings Group R with five stories or less has a different min requirement of 100 sq. ft. of solar PV or green roof. If you are unable to install solar PV, you must install a green roof. Standard roof replacement projects involving a new roof membrane or insulation are not required to comply with NYC LL 92 and NYC LL 94.