The Fire Protection Research Foundation has published a new, two-part report on the performance of residential sprinkler systems with sloped or sloped and beamed ceilings. Current test and design criteria for home fire sprinklers in one and two family dwellings (UL 1626 and 1626A) are limited to smooth, flat ceilings and sloped ceilings in specific limited configurations. Local authorities have limited available design guidance for the large number of one- and two-family dwellings that are constructed with ceiling geometries that fall outside the scope of the current listings. This report describes the results of an experimental and analytical study of the performance of residential sprinklers in home fires with a range of typical ceiling geometries. Its purpose is to provide the technical substantiation for design guidance in NFPA 13D, Installation of Sprinkler Systems in One and Two Family Dwellings and Manufactured Homes.