NFPA 13D is designed specifically for one—and two-family dwellings. NFPA 13R covers larger residential occupancies up to four stories in height, and NFPA 13 covers larger buildings and highrises. NFPA 13 provides the highest level of fire protection of the three. According to NFPA 13, commercial buildings are required to be inspected and tested annually to ensure their facilities meet the minimum requirements of the Life Safety Code.