Hotel Damier

Hotel Damier is an historic upmarket hotel with an impressive guest list including George Bush, Margaret Thatcher, Eddy Merckx, Adamo and Sheryl Crow and is located in the “Grote Markt” in Courtray.

Because of a recent extension to the Damier, to provide space for a hotel bar, the acoustic consultant specified a CDM-BOX-IN-BOX system to prevent noise generated in the bar area from becoming a nuisance in other areas of the hotel.

The CDM-BOX-IN-BOX system comprised:

  • CDM-FLOAT bespoke modular acoustic floating floor designed with an oversized void to accommodate the various building services ducts, pipes and cables – these also had to be isolated where they penetrated through the floating floor.
    The benefits of this type of floor are:

    • Quick and simple installation thereby minimising disruption to the building
    • The floor can be designed to accommodate any working load and deflection and to accomodate any building services
  • CDM-WH resilient wall ties used to isolate the secondary wall, which were supported off the CDM-FLOAT floor, from the supporting walls
  • CDM-PHR resilient spring ceiling hangers were used to isolate the heavy suspended ceiling from the supporting structure.

Audiolokalen UZ Leuven

Within the university hospital campus “Gasthuisberg” in Louvain, there’s a new building next to the urgencies, where the audio rooms are located. The aim is to test patients on their hearing capabilities with the newest technologies in their field, this being the reason why the acoustic consultant Daidalos imposed high level acoustic isolation between all the spaces here. The rooms are made following the “box-in-box” principle.

The concrete floor of every audio room is floating on resilient floor battens, these being CDM-FLOOR-T. These battens result in an air void of approximately 100mm, which allows the air stiffness in the floor system to become less dominant. Located between the floor battens is an absorption layer to avoid standing wave effects.

The light gypsum walls are installed on the edge of the floating floors and acoustically decoupled from the structural ceiling by means of the CDM-WALL-FIX principle, to avoid any direct stiff contact.

The ceiling is constructed from gypsum boards which are acoustically decoupled from the ceiling by high performing spring-dampeners CDM-PHR. For reasons of fire-resistance, the maximum load per hanger is limited, in order to take up the relatively high mass of the lowered ceiling.

Additional difficulty consists in the integration of a “Faraday cage” in the box-in-box setup, being the reason why all metal connections had to be treated with the highest care, asking for very specific and complex solutions for the building nodes. One of the rooms occupies a test chair, this being “gigatorque” and is predominately used to test patients during a certain rotation. This chair has been installed on CDM-PADS via a specific anchored steel baseplate incorporated within the reinforced concrete plate.

9 Marylebone Lane

9 Marylebone Lane is a new-build high quality residential building comprising 2 basement levels, lower ground, ground and seven upper floors. The site is located in between Oxford Street and Wigmore Street.

The Jubilee Line runs directly beneath the site and the acoustic consultant, Hoare Lea, specified that the building needed to be supported on elastomer bearings with a maximum natural frequency of 15Hz.

The building is isolated at the base of columns and walls on top of the ground floor slab. Sensitive areas on the ground and lower ground floors are isolated using box-in-box constructions.

The bearing stiffnesses were used in the structural analysis to ensure that the correct bearings were used at each support location.

The 3 apartments and the gymnasium that were below the level of the main building isolation were built off CDM-MONT-100 concrete jack-up floating floors to create box-in-box constructions.

Installed Bearing prior to Column being poured

Architects Impression of Completed Building

Delhaize – Kattendijkdok

In some multi-functional buildings, supermarkets are located under an apartment block which, if not isolated, may cause serious noise nuisance for the occupants. In particular, the rolling noise of pallet trucks is clearly audible as it is easily transmitted via the floor and as most of the loading and unloading activities are planned early in the morning or late in the evening, when background noise levels are very low, this is obviously of particular concern when designing the building. The main strategy of acousticians and architects to prevent this kind of noise nuisance is to decouple the entire floor of the supermarket and unloading areas by using a continuous mat isolation solution.

For the Delhaize project about 3000m² of floor have been decoupled by using a resilient recycled rubber mat with a wavy surface (CDM-MAT). In critical zones like the unloading area the applied mat solution was adapted to provide extra acoustic isolation. A floating reinforced concrete floor was then installed on top of the mat. Lateral decoupling of the loadbearing walls, columns, and services running through the floor was achieved by using CDM-PERIMETER strips which were meticulously installed to avoid all possible bridging.

CDM specifically developed for rolling noise isolation applications a full range of wavy surface mats (CDM-MAT), based on DLv,rn index. This new concept is used in France and based on an extended frequency range of 50 to 500 Hz, for better evaluation of the low frequency response and performance. The CDM-MAT has a profiled underside thereby minimizing contact points across the floor and reducing the structure-borne noise transmission to the supporting structure of the building whilst still providing a low resonance frequency for the floor system. The high density of the chosen CDM-MAT means a long-term warranty of the physical and acoustic performance of the system can be provided as the effects of creep are of no importance. Low density resilient mats are known to suffer from creep leading to reductions in elasticity and noise isolation performance in the long term.

Myriad by Sana Hotels

Located at Parque das Nações, a leisure, commercial and residential new district in Lisbon, the 5 stars hotel MYRIAD BY SANA HOTELS was executed in 2 concrete structure parts and glass surfaces with 142m height. The building is connect to the existing Vasco da Gama Tower, a metal structure tower inaugurated in 1998 during the universal exposition in Lisbon, EXPO 98, an emblematic structure during the exposition but also actually a national icon.

To isolate the technical rooms at 2nd, 21st and 23rd plants, several CDM-MONT-100 concrete slabs 100 mm thick with a natural frequency < 8 Hz were installed.

Besides this application, all concrete floor in the hotel were isolated with underscreed solution CDM-MTC-4,5.

A Jacuzzi and a swimming pool  located in the 22nd plant were also acoustically isolated with special CDM-POOL system.

Installation of CDM-MONT boxes and reinforcement bars

Installation of CDM-MAT

Installation of CDM-POOL

Ebury Square

Ebury Square is a high end residential development in Chelsea. There are two new buildings, one of which is built directly on top of the cut-and-cover tunnel of the Circle and District lines in between Sloane Square and Victoria.

The vibration levels on site are very noticeable and to limit the structure-borne noise levels both buildings were isolated on 3.2Hz CDM-CHR-BOX pre-compressed spring boxes. In total 341 spring boxes were designed, manufactured, supplied and installed by CDM. All springs went through a rigorous testing and quality regime to the satisfaction of all parties.


Barco, a significant leader in the market of projectors, is building a completely new headquarter complex at Kennedy Park in Kortrijk with a total area of 60000m². The architects Jaspers-Eyers designed a very strong modern building; the vast circular concept intended to echo dynamics, compactness and innovation. The main building houses a training room, conference facilities and restaurant. In addition several rectangular office blocks are also being built to provide space for a total of approximately 1500 employees.

On the first floor of the circular main building is a large meeting room, for which the acoustic consultant specified CDM-FLOAT a high-quality acoustic floating floor system. The CDM-FLOAT is a modular system which is pre-assembled at the CDM factory. It comprises high performance isolation pads and an absorption layer bonded to a lost formwork panel onto which reinforced concrete is then installed. The same system was also used for various machine rooms housing HVAC units on the upper floors.

One of the adjacent buildings houses a test facility which examines the effect of induced vibrations on new products. In order to sufficiently isolate vibration from the rest of the building two concrete inertia bases were installed in the basement on to which the test equipment was mounted. Both inertia bases were installed on flexible steel springs, with a resonance frequency of 2.5 Hz, and elastic lateral buffer pads were inserted, by means of special air cushions, in order to limit horizontal movements.

CDM-FLOAT - concrete floating floor

concrete inertia base

NYU Abu Dhabi

New York University is building a new campus in Abu Dhabi on Saddiyat Island. The new campus has 117,000m² of Academic
Space, 142,000m² of housing for students and staff, 34,000m² of car parking and 8,200m² of specialist research areas.

One of the buildings on the campus is the Arts building which contains a state-of-the-art Auditorium, a Black Box Theatre and a Recital Hall. The Acoustic Consultant specified that all three of these performance spaces should have 150mm thick concrete floating floors on a 100mm void with a system natural frequency of <10Hz. The CDM-QDECK system was used which was designed to take perimeter wall loads of over 100kN/m.


Sedmikraska residential building was commissioned by the Daramis Group in the 9th district of Prague located directly over the twin tunnels of the Metro Line B. Measurements confirmed that vibration isolation of the building was required; although this was already expected because all other new buildings in the area had been isolated or, if not, were having noise problems.

CDM-SEB elastomer bearings, with a design load of approximately 6 MPa, were installed at the top of pillars and walls just below the ground floor slab. Elevator shafts were isolated from every floor slab to provide resilient load transfer between the isolated and non-isolated structure.

CDM-SEB system on top of a column

CDM-SEB deflection measurement

80 Marine Parade Drive

Reported by the Acoustician, the frequency response of the existing gym-floating floor was measured in a heel drop test. The measured response frequency of the floor was broadly in a range centred at about 15 Hz.

CDM-CA Ltd designed, supplied and installed a retrofit floating floor solution. With use of past CDM lab test data, and by performing in-situ mock-up trials consisting of various material and cross-sectional designs, 3-different floor build-ups were tested, 1-remained as being 100% successful, resulting in no perceived vibration or audible noise in the tenant’s suite.

The CDM-FLOAT solution eliminated the 43 dBA measurements previously recorded, using a specific floor buildup not involving a concrete floating slab, to achieve a sound level of less than 35 dBA.

Finished gym floor