London, United Kingdom

Property owner


Main contractor



Acoustic consultant

Ramboll Acoustics (for client) ; Alan Saunders Acoustics (for Overbury)

Structural engineer


6 areas – 1774 m²

Building type

Sports & Leisure


Gym & Sport

Intervention level


A 42dB impact sound isolation was achieved by installing a composite dry floor construction.

Equinox is a large USA gymnasium operator and their first venture in London is in High Street Kensington. The site they chose is on the 5th floor, directly above Sony Music where Simon Cowell works, and directly beneath Kensington Roof Gardens, which is a popular and very trendy night spot.

Ramboll Acoustics specified that a floating floor was required to reduce impact noise levels from the gym to <55dB L’nT,w. However it soon became clear that the floating floor would have to ensure that no significant disturbance was caused to Sony Music directly beneath.

CDM-UK worked closely with the contractor and consultants to fine-tune the floating floor system and built several mock-ups to verify the performance.

The final design consisted of a CDM-LAT isolation rail supporting a composite dry floor construction. The floor under Group Fitness, where all of the gym classes are held, also had layers of steel plate to optimise the low frequency performance.

The on-site performance at the end of the job was measured as 35dB L’nT,w although this was dominated by background noise as the performance of the floating floor was so good. The improvement from the base concrete floor was 42dB.

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