Maisonettes, duplexes and triplexes in the city of Montreal have enjoyed much success since they were first built some 60 to 100 years ago. They currently account for half of the city's dwelling units. However, they pose some problems in today's context. Current standards and various innovations in new housing construction serve to underscore some of the limitations. Rooms can be small, kitchen can be dysfunctional, there is little storage space. Describes research carried out to look at the potential for revitalizing plex housing.