Firestop of mechanical and electrical penetrations in these four-story family houses

Architects impression Riedpark a four-story multi-family house in Lauchringen, Germany

The 60 minute fire rating requirement of the buildings had to be met without having the lower timber surface of the CLT slabs covered with gypsum board. The non-standard configuration of the mechanical penetrations made the design of the right firestop solution even more challenging. Our solution was a joint fire test with the manufacturer Lignotrend. All mechanical and electrical penetrations were tested on their floor. For the mechanical applications, our CFS-C EL endless collar was used. Our CFS-BL P firestop blocks were selected to seal the large cable penetration openings.

The challenge

Since 2015, legal changes in the federal state of Baden-Württemberg allow the use of wood materials in tall buildings (up to building class 5) without the additional insulation with non-combustible gypsum boards. Architect Jörg Kaiser had originally planned a hybrid construction made of reinforced concrete and wood, as the risk of fire in a massive wood class 4 building was still a major concern.

Riedpark had a fire rating requirement of 60 minutes and both buildings have been designed without covering the lower CLT surface of the slab with gypsum board, which theoretically reduces the resistance in a case of fire. Despite the changes in the regulations, the lack of internationally approved solutions for firestop in wood creates uncertainty in meeting the high fire safety standards. In addition, the complexity of the mechanical penetrations that were in a non- standard configuration (waste water pipes in the corner, elbow pipes), made the firestop design more challenging for M&E planners and firestop engineers. Also, sound insulation was a key concern for the architect.

Our solution

Photo of the interior of the Riedpark wood construction project

To make sure that the strict fire protection requirements are met, Hilti conducted a joint fire test together with Lignotrend. All the mechanical and electrical penetrations designed for this building were tested with the right firestop solutions on a Lignotrend floor. With strong fire test evidence, Hilti Firestop Specialists convinced the architect and the local authorities about the fire performance of the system.

In this project, there were many waste water services in non-standard configurations, e.g. corner applications. For these applications, Hilti CFS-C EL firestop endless collar was used. It has a wide range of approvals for various pipe configurations, including elbow pipes, inclined pipes, and pipes in corners etc. For the electrical cables, conduits were used that were passing through a large opening. Hilti CFS-BL P firestop blocks were selected as a solution to seal the large openings with the cable penetrations.

CFS-BL P firestop blocks come with a broad range of approvals for mixed penetrations, as well as being fast and easy-to-install. As a preformed and ready-to-use product it also helps reduce overall construction time. Also, it provides high acoustic insulation and carries the Hilti Clean-Tec logo, which stands for more environmentally-friendly Hilti products.


  • Image of a Hilti CFS-BL P firestop block

    CFS-BL P firestop block

    Preformed firestop blocks for sealing cable penetrations

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