A NEW REPORT suggests doing away with the second stairwell in buildings of three-to-six stories could boost housing production – a case of addition through subtraction. Due to fire safety, building codes for three-to-six story structures currently require two points of egress. The new proposal for one stairwell is accompanied by additional fire safety requirements such as sprinklers, fire-treated materials, less distance to the point of egress, and windows that meet emergency rescue escape requirements.