Light wells with windows in exterior walls that are located below the outside ground level shall be protected from the ingress and egress of rats by one of the following methods.
(a) Installing over light wells cast iron or steel grills or steel gratings or other material of equal strength and rat-resisting properties, with opening in grills or gratings not to exceed one-half inch in shortest dimension.
(b) Installing securely to and completely covering existing metal grills that are broken or have openings larger than one-half inch in shortest dimension, or otherwise defective, with expanded metal of 18 gauge or heavier, having openings not greater than one-half inch in shortest dimension, or with 16 gauge or heavier wire cloth with one-half inch mesh.
(c) At the option of the person in custody of the business building, the opening in the wall of the building below the grate may be entirely closed with brick or concrete or partially closed and the remaining open space covered with 19 gauge or heavier wire cloth, with mesh not to exceed one-half inch.
(1964 Code, § 19-361)