Single-stair housing is a mid-rise typology, typically up to six storeys, organised around one shared staircase that also serves as a social and daylighting spine. Commonly deployed for infill projects, the typology allows taller, more efficient residential buildings on narrow plots—a strategy that increases housing supply and supports walkable, mixed-use neighbourhoods.

The Denver Single-Stair Housing Challenge, organised by Buildner in collaboration with SAR+ Architects, solicited design solutions that explore how the typology can be adapted to Colorado’s housing and regulatory context. Sideshore’s entry, FILL GOOD Inc., proposes a six-storey, multi-family block that emphasises communal life and spatial economy through a deliberate programmatic sequence.

The ground floor is conceived as the building’s communal heart. A series of shared “third spaces”—a den for reading or remote work, a coffee nook for informal gatherings and a workshop for repairs and tinkering—expand domestic space, offering communal alternatives to the privacy of apartments and the anonymity of the streets.

Above the ground floor, the remaining levels accommodate a mix of unit sizes. Larger two- and three-bedroom apartments occupy the middle floors, while studios and one-bedroom flats sit on the upper levels. This vertical stratification encourages diverse household types to coexist within a compact footprint. Circulation is economised to maximise space, while every apartment retains access to daylight, privacy and views.

Sideshore’s mobility strategy further reduces the project’s footprint. By limiting on-site parking—providing two dedicated spaces and generous bicycle storage—the design supports a “sans voiture” lifestyle, redirecting space to communal uses that strengthen the building’s social and environmental aims.