Tekenpunt / Projects / Roof extension Amersfoort
Completed project · Roof extension PLAN N°PRJ-AMF-2025 / SCALE 1:100 / 2025

Roof extension in Amersfoort

A 1960s mid-terrace house in Amersfoort-Soesterkwartier received a full extra storey. The distinctive feature of this project was the narrow plot width, which demanded a precise structural solution. We delivered the design, structural engineering and building permit as a single package.

TypeRoof extension
LocationAmersfoort
Surface area+26 m²
Lead timeBuilding permit 8 weeks
Year2025
ResultExtra storey
§01 From sketch to completion

The complete process

01 · Challenge

Narrow plot in a row of identical houses

The property in the Soesterkwartier stood in a block of virtually identical terraced houses. The plot width was only 5.4 metres, which meant the roof extension had to be structurally coordinated with precision relative to the neighbours. In addition, there was a maximum building height that is strictly enforced in the neighbourhood: the roof extension could not exceed the ridge of the adjacent properties. This significantly limited the margin for standing height.

02 · Our approach

Knee wall lowered, roof surface used to its maximum

We strategically lowered the knee wall and designed the roof extension so that the ridge of the new storey remains just below the maximum building height. By setting the extension 15 centimetres back from the front facade, the impact on the streetscape is minimal. The structural engineer calculated two bay spans precisely so that the steel beams could be neatly fitted within the existing wall thickness. The application went through without objection.

03 · Result

26 m² without exceeding the building height limit

The result is a full bedroom floor of 26 m² with two bedrooms and a small study. The roof extension fits seamlessly between the neighbouring properties: height, materials and facade detailing have been deliberately matched to the surroundings. The building permit was granted within 8 weeks, with no objections from neighbours. The contractor started the shell work the week after the permit was issued.

Key project details

Drafting
Construction drawing + details
Permit
Building permit, no objection
Structure
Steel beam and knee wall calculation
Neighbour coordination
Setback check for adjacent plots
Lead time
Permit arranged in 8 weeks

What we delivered

  • Existing and new situation drawings (floor plans, elevations, sections)
  • Complete building permit application with the municipality of Amersfoort
  • Structural calculation for steel beams and knee wall details
  • Building height check including profile sketches of adjacent plots
  • 3D impression for building permit application and client
  • Execution-ready detail drawings for the contractor
§03 Adding a roof extension yourself?

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Last updated: June 2026 Content reviewed by the Tekenpunt team · in-house architect & KIWA-certified structural engineer