 New examples of housing in less-developed economies, designed by professionals to be incrementally upgraded in a user-controlled process, come to light in Chile, Mexico, and South Africa.Mainstreaming of open building is a response to the pressures, conflicts and waste caused by continued adherence to rigid functionalism – that is, defining functions and designing buildings to fit.Open building is also a pragmatic answer to a state of technical entanglement in buildings that has resulted from the incremental addition, over a long period of time, of new technical systems and the “ownership” of these new systems by different trades who rarely cooperate.