The misplaced architectural Step A0 in residential design means that homes cannot be easily connected or subdivided. Research into the flexibility problem has been ongoing within the academic sphere of material efficiency for the past century, however solutions have been too complex to be functional or understandable to the end user. Flexistorey has simplified the task for future generations of end-users by opening up or closing three doorways between units. The units can therefore be subdivided easily by blocking up the door way. We call these doorway-valves. Up to six different home size options can be created to provide for full lifetime occupancy.