Every residential building shall be ratproofed and maintained in a ratproof condition by the owner or licensee of that building.
Ratproofing shall include construction designed to prevent rats from entering a building by blocking off or stopping up all passages by which rats may gain entry.
Ratproofing shall also include the closing of openings in exterior walls with materials through which rats cannot penetrate.
Ratproofing shall also include such interior rat stoppage, harborage removal, and cleanup as may be necessary to reduce or eliminate rat-breeding places.
D.C. Mun. Regs. tit. 14, r. 14-804