01 · Challenge
Staircase flat required additional foundation and owners' association coordination
The owners of an upper-floor flat in Utrecht-West wanted to convert the unused attic level into a full bedroom storey. The 1950s building had a flat roof that had already been reinforced in an earlier renovation, but the structure had never been calculated for an additional storey. In addition, the owners' association required written approval and the municipality was strict about the maximum building height in this post-war residential block.
02 · Our approach
Lightweight steel frame with minimal additional load
We chose a lightweight steel frame with insulated sandwich panels to keep the additional load on the existing structure to a minimum. The roof extension matches the building line and materials required by the Utrecht-West neighbourhood guidelines. We compiled the owners' association dossier, conducted the structural pre-consultation with the municipality, and submitted the building permit application. The extension remained well within the permitted eave height.
03 · Result
Light upper floor with extensive glazed facade elements
After completion, the clients had 30 m² of extra living space with generous roof windows on the south side. The owners' association agreed unanimously and the municipality granted the permit within 6 weeks. The contractor worked from the execution drawings without any additional questions: all dimensions, details and junctions were fully worked out. The property increased in value immediately due to the larger usable floor area.