by 1910, commercial rooming houses began to resemble an "inexpensive hotel", with multi-story buildings, often 25 to 40 years old, with the owners using the house as an income property. the operators, typically former boarding house managers, were getting out of the business of providing meals. this enabled the owner to convert the shared dining room and parlour into additional rental rooms and stop paying for the preparation of meals. there were often sixteen to eighteen rooms, with either central heating or tiny in-room heating stoves. a single bathroom was usually provided, with hot water only available on certain days and limits to the number of baths allowed per week. blacks were not allowed in most rooming houses, due to segregation, except in black rooming houses. old run-down hotels were converted into rooming houses. some entrepreneurs even converted empty warehouses into inexpensive rooming houses. prior to 1900, elevators were rare, so rooming house residents had to climb stairs. the hasty conversion of old houses and warehouses into blocks of rooms typically meant that the walls were thin, so residents could hear each other.