Solar thermal collectors on a pitched flat roof

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A residential building in Altenburg, Germany, required the installation of solar thermal tube collectors on a flat roof with a seven-degree pitch. Walraven provided the engineering expertise and support system needed to install the collectors without penetrating the roof cladding while ensuring long-term stability and performance.

Installing collectors without roof penetration

The project presented several technical challenges. The solar thermal collectors needed to be installed on a pitched flat roof while maintaining the integrity of the roof membrane.

In addition, the support structure had to:

  • Be positioned precisely on the load-bearing roof ribs.
  • Compensate for the roof’s seven-degree pitch.
  • Minimise wind exposure.
  • Accommodate sufficient ballast without extending too far beyond the roof edge.
  • Ensure reliable performance under local wind and snow loads.

Tailored rooftop support solution

Walraven provided comprehensive technical consulting, planning and engineering support throughout the project.

The solution was based on the Walraven Yeti® 480 support system, which can compensate for roof pitches of up to seven degrees while supporting compressive loads of up to 20,000 newtons. This allowed the project team to install the collectors without penetrating the roof cladding and ensured optimal load distribution across the roof structure.


The project included:

  • Engineering support and structural calculations.
  • On-site technical consultation.
  • Detailed drawings, parts lists and preliminary structural calculations.
  • Collaboration with a structural engineer to verify positioning and load requirements.


The installation also incorporated Walraven BIS UltraProtect® 1000 surface protection, providing excellent corrosion resistance and long-term durability. The injection-moulded components, manufactured from recycled materials, are weather- and UV-resistant and allow installation or removal without damaging the building fabric.

Careful planning and implementation

The success of the project relied on precise planning and coordination. The Walraven Project Manager, provided extensive support through on-site consultations and detailed technical discussions during the planning phase.

Walraven’s application engineering team assisted with the technical design of the installation, ensuring the system met all structural and performance requirements while delivering a practical and efficient rooftop solution.

Delivering long-term performance

The completed installation provides a secure and future-proof support structure for the solar thermal collectors while preserving the integrity of the roof.

The modular design allows the system to be extended if required, while the load-bearing construction has been engineered to withstand local environmental conditions. Combined with its durability, corrosion resistance and non-penetrating installation method, the solution delivers an effective and sustainable foundation for rooftop solar thermal technology.

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