(a) All foundation wall ventilator openings shall be covered for their entire height and width with perforated sheet metal plates of a thickness not less than 18 gauge, or with expanded sheet metal of a thickness of not less than 18 gauge, or with cast iron grills or grates, or with any other material of sufficient strength and equal rat-resisting properties. The openings herein shall be small enough to prevent the ingress or egress of rats, and in no instance shall be larger than one-half inch.
(b) All foundation, exterior wall and roof openings, excluding doors, windows and those openings used for the purpose of ventilation and light, such as those openings around pipes, electric cables, conduits, openings due to deterioration or damage, broken masonry or concrete, or other openings which may allow the ingress or egress of rats, shall be protected by closing such openings with cement mortar, concrete or masonry, or close-fitting sheet metal, or suitable size pipe flanges, or other material with equal rat-resisting properties, which shall be securely fastened in place.
(1964 Code, § 19-357)