A three-story complex in the interior court of the Mercure Hotel in Munich, with room for twelve guest rooms, is connected through a walkway to the existing building, where the most important basic structural requirements were provided in the already existing underground garage. The structural reserves had to be sufficient to bear the load of the extension building. This, however, had a decisive effect on the architectural design, the construction and the sound insulation of the building – and confronted the parties involved in the project with difficult questions. “Initially, the specifications for sound insulation and the basic structural conditions seemed completely contradictory,” reported Christian Olufemi of the architectural firm of the same name. For this reason, experts from the company Schöck, together with the architects and the structural engineers, had been involved already in the early stages of the planning phase to enable recommendations – in close coordination with the building physics engineering consultants ig-bauphysik – for a solution to meet the requirements for impact sound insulation in the hotel. For execution in precast- and in-situ concrete, Schöck Tronsole was the ideal solution for meeting the client’s specifications for sound insulation.
Challenging specifications for sound insulation
The minimum requirements for sound insulation imposed by the building authorities are regulated in DIN 4109. For stair flights and landings in hotels, a numerical standard impact sound level of L’n,w = 58 dB is required. In buildings with elevators, no requirements on stair flights and intermediate landings are imposed. However, at a numerical standard impact sound level of L’nT,w = 35 dB, the requirements under private law imposed on the Mercure Hotel in Munich were considerably more rigorous. “Requirements on impact sound insulation of that order are quite unique. Never before had we been confronted with an implementation like that,” reported Jürgen Bauer, Technical Consultant at Schöck Product Management.
Impact sound reduction by way of acoustic decoupling
The Schöck Tronsole product program offers a complete sound insulation system for straight and helical stair flights for acoustically decoupling structural components. The project participants accordingly found the solution also in Schöck Tronsole Type F and B. Both types are optimally suited for the stair structures: the stairway in the extension building of the hotel consists of precast elements, the rest of the building having been implemented with in-situ concrete. Considered from architectural aspects, the single- and double-flight stairs wind around a continuous wall leading from the ground floor to the second upper floor in the stairwell.
For the sound-insulating connection of the precast stair flight to the intermediate landings and floors, the planners used the impact sound insulation element Schöck Tronsole Type F. For acoustically decoupling the stair flight from the ground slab, Schöck Tronsole Type B was used. Separation of the stair flight from the ground slab over the full surface ensures that no dirt can get into the joint. “A single stone in the joint reduces the sound insulation by approx. 10 dB,” explains Jürgen Bauer.
The Tronsole types are fitted with Schöck Elodur neoprene bearings, which provide effective impact sound insulation. The acoustic parameters for Schöck products are tested in accordance with DIN 7396, achieving, for Tronsole Type F und Type B, a numerical impact sound level difference of ∆L*n,w ≥ 30 to 3 dB. Renewed and extended testing in July 2010 in accordance with DIN 7396 confirmed the very good acoustic parameters of the Tronsole product program. These tested parameters enable reliable planning and verification procedures.
Rapid installation without additional measures
Installation of the impact sound insulation elements took place directly on-site. The integrated adhesive insulation tapes enable easy and rapid gluing of the Tronsole elements to the precast element. In the first step, the precast stair was cleaned from dust and dirt. After that, the Tronsole was glued directly to the stair, without additional measures; any protruding material was easily cut off by the construction crew with a cutter. Tronsole Type F is additionally fitted with a clip hinge that provides high form stability and simple handling during processing.
Impact sound insulation at the highest level
Tested parameters and rapid installation are one aspect, but all-decisive in the construction of the extension to the Mercure Hotel were ultimately the acoustic measurements on location. They were intended to show whether the high requirements placed on sound insulation could be met with Tronsole. The result confirmed not only satisfaction of the high requirements placed on impact sound insulation, but also that the measured results for L’nT,w = 32 dB considerably excelled specifications.
“The project was for us and all parties involved a great challenge. It was, however, also an incentive to demonstrate that our products and that we, with our service, are able to successfully meet such demanding requirements. Even greater satisfaction, of course, resulted from the verification measurements carried out,” said Jürgen Bauer. The extension building in the Mercure Hotel has been open to guests since May 2019. The Tronsole products from Schöck are an important building block that contributes to the superior living quality of the 4-star extension.