Leonard Avenue is a two-stage project, the first of which was completed in 1999 and consisted of the interior conversion of a four-storey medical arts building into 51 units of affordable housing. The most recent stage consisted of adding 26 new residential units by dropping two-storeys of pre-fabricated modular units on the roof of the existing building. The new Single-Room Occupancy units provide housing for people currently in shelters. It was necessary that the existing tenants could remain living in the building throughout construction. Executing the design through pre-fabrication resolved this constraint and freed up the roof for construction. The project increased both building density and green space. The existing infrastructure is extended to the roof and a series of new interconnected spaces integrate the new and existing units, offering all residents additional outdoor amenity space.