Floating floor system for generator plant room
Mason UK was appointed to design and supervise the installation of a bespoke floating floor system for a generator plant room on Level 21 of the West Tower at 2 Finsbury Avenue. The building is part of British Land’s Broadgate Quarter redevelopment and is one of the most prominent commercial developments in the City of London. The works were delivered for Sir Robert McAlpine, the main contractor, with Morrisroe undertaking the installation under Mason UK’s technical supervision.
The selected type of flooring needed to perform a dual role: supporting heavy plant equipment while delivering effective acoustic separation in a highly sensitive environment.
Managing generator noise in a high-rise building
The generator plant room is located at the very top of the building, directly beneath the roof and high-value penthouse office accommodation. As a result, stringent acoustic criteria were applied, with a clear requirement to reduce noise and limit vibration transmission into the occupied spaces below.
Without appropriate treatment, generator and plant operations can cause significant disturbance to building users. Airborne and Structure borne noise need to be controlled. Therefore, the design focused on isolating the plant at source and delivering reliable noise reduction through structural separation, rather than relying solely on secondary acoustic finishes.
Box-in-box construction for acoustic performance
Working to Hann Tucker Associate’s specification, Mason UK developed a robust floating floor solution based on a box-in-box construction, using a floating structural slab to decouple the generator plant from the building frame. The system centres around a 125 mm reinforced concrete floating floor with a 75mm air gap, supported on Mason FSN LDS rubber jacks with a natural frequency of between 8 and 10Hz.
The jack layout was designed to accept the plant weights and heavy wall construction. Dedicated jacks were required to accept the point load of the generators, which were supported on high deflection spring mounts providing the primary vibration isolation. The system was designed to control re-radiated noise and vibration from the plant during operation.
Reducing noise while meeting thermal requirements
To satisfy the project’s thermal performance targets, the floating floor was constructed on a layer of high-compressive-strength FOAMGLAS® insulation. Spreader plates were introduced at each jack location to distribute the significant loads evenly through the insulation layer while maintaining both the thermal and acoustic separation required.
Project delivery and outcome
Mason UK supplied the jack systems in October 2025, with the FOAMGLAS® insulation installed during the first week of November. The steel reinforcement and jack-up system installation shortly followed, and the concrete slab was poured soon after that. Once the concrete achieved the required strength, cube testing was completed and jacking operations commenced to lift the floor to provide the 75mm air gap. All works were completed under the supervision of Mason UK’s Senior Project Engineer, Tom Van Dongen, with Director Steve Hart overseeing the works.
The floating floor was successfully jacked to its final level, fully inspected and signed off, completing Mason UK’s scope on the project. Delivered more than 20 storeys above ground, the system provides effective control of airborne and re-radiated noise for critical plant equipment in a challenging commercial environment.
2 Finsbury Avenue stands as another example of Mason UK’s expertise in complex floating floor construction for demanding commercial developments, combining acoustic performance, structural capacity and practical installation — all with exceptional views across the City of London.
To find out more about the range of other projects that we’ve completed over the years, visit our Case Studies page.
