In a Paris suburb, a rooftop extension has added 20 affordable timber homes to an existing residential into a modern visitors centre building. The project meets growing housing demand and stricter energy requirements while addressing indoor climate challenges. The municipality needed to provide more affordable housing in a dense urban setting, near the protected surroundings of Versailles. Meanwhile, indoor climate conditions in France are under pressure, with a 51% rise in cooling degree days and a 95% increase in people unable to keep homes warm between 2015 and 2022.

SAM Architecture and social housing developer In’li added 20 timber duplex homes on top of an existing 46-apartment building, avoiding land consumption and carbon-heavy new construction. The homes are built around a shared wooden walkway — a communal “street” designed to foster neighbour interaction. Though compact (with bedrooms of 10–12 m²), the homes feel open thanks to roof windows that bring in daylight and views of surrounding trees. Timber cladding adds a warm, natural feel. To limit overheating, the homes feature solar control glazing, external awning blinds and support natural ventilation. All homes meet France’s RT2012 standard, with total energy use for heating, hot water, lighting and ventilation kept below 50 kWh/m² annually.

This project delivers affordable housing without taking up green space or building anew. It’s a scalable model for low-carbon urban densification — one that supports both climate goals and resident well-being. As climate extremes become more common, passive design strategies like shading, ventilation and daylight access will be key to creating homes that are both comfortable and future-ready.