In the context of the modernisation of old buildings, acoustic requirements evolve in parallel with construction techniques. Traditionally, achieving good acoustic performance has meant creating large air gaps under heavy floating concrete slabs, which limited the range of possible of intervention techniques in existing structures, sometimes old and offering little space. Today, thanks to innovation in construction systems, including the use of spring supports, it is possible to achieve high levels of sound insulation while significantly reducing the necessary height of the system.
This progress opens up new perspectives for renovation, by reconciling technical efficiency, space saving and respect for heritage constraints.
Reform of historic buildings for acoustic performance
Old buildings in urban areas, prized for their architectural and historical value, are increasingly attracting developers wishing to transform them into high-end housing. The objective: to offer modern comfort in a setting steeped in history. Among the most complex technical requirements is acoustics, an area for which these buildings were not designed, at a time when the urban sound environment was very different, without motorized traffic.
Often constructed of wood and stone, with thin floors, these buildings easily transmit airborne and impact noise, whether from neighbouring rooms or from the outside, including vibrations caused by heavy vehicles. Traditional acoustic construction solutions therefore require a difficult choice: either to preserve the original structure at the expense of performance, or to obtain good insulation by significantly modifying the interior. In some cases, heritage protection further limits the possibilities for intervention.
New sound insulation techniques now make it possible to reconcile respect for old buildings with high performance. A good example of this is the decoupling of structures: thanks to innovative flexible supports, it is possible to adapt the solution to different types of construction while ensuring effective insulation.
Theory shows that lightweight wooden structures, because of their low mass, react more strongly to noise and impacts than heavy structures. This makes their insulation more complex. Adding weight to the structure could improve insulation, but it often exceeds the load-bearing capacities of the building.
The same logic applies to suspended elements: a low natural frequency, which guarantees good insulation, can be achieved either by increasing the mass or by reducing the stiffness of the supports – for example with springs. This allows for the installation of a lightweight floating floor with excellent acoustic performance, while respecting weight constraints.
We also have to take into account the air contained in the plenum (the space between the floor and the suspended floor), which acts as an additional spring. The smaller this space, the more rigid it becomes, which can affect the effectiveness of the supports.
To remedy this, AMC recommends partially filling the plenum with mineral wool. This limits air mobility, adds damping and reduces sound transmission. It also prevents resonance from the cavity, thus strengthening the overall insulation of the system.
It is with these elements that AMC has installed two floating floors that meet all these common demands.
- Respect for the original wooden structure
- Lightweight materials
- Low height
- High acoustic performance
In addition, each of these floors is intended for different demanding applications:
- A floor for a cinema room
- A floor for a gymnasium
Floating floors for a cinema and gymnasium
In a recent case, AMC's team of technicians calculated, designed and then supervised the installation of the spring supports on which the slab will float.
These supports, created specifically to adapt to the considerable thickness of this slab (20 cm) as well as to the needs of 25 mm of plenum, in turn filled with mineral wool, were raised gradually and one by one until the required height was reached.
The shape of the metal housing allows the round rebar to be taken directly from the slab for better mechanical strength and integration into the slab.
Their architecture allows lifting by means of the top central bolt, accessible from its upper part. The design means that this bolt can be accessed at all time, advantageous if subsequent adjustments are necessary
According to this method, the springs are loaded gradually to ensure the greatest respect for the structural integrity of the concrete slab, which is still hardening after only 5 days since casting. Taking this into account, a team of technicians from AMC-MECANOCAUCHO went to the site to supervise the installation of supports and then the lifting of the slab. The certified surveyor of the site later confirmed that the required height was reached with excellent levelling.
AMC-MECANOCAUCHO® trains your installation teams through an application engineer. This trainer explains the installation methodology and gives all the tips to increase productivity.
Calculation of a floating floor or slab
The design of this engineering work is carried out by AMC's team of engineers, who ensure that its design meets all the requirements specified by the customer. However, it all starts with a simple application, in which the following data is enough to initiate the design of the suspension:
- Weight per m² of the floor (or thickness and materials)
- Floor plan to be suspended
- Natural frequency required by the acoustician
A recommendation will be made by selecting our most suitable supports to establish a first layout proposal. Other interesting data from the rest of the process are:
- The need to isolate perimeter lined walls
- Distribution of dead and operating loads on the floor
- Lifting height required by the acoustician
- Presence of mineral wool
- Presence of machines producing vibrations
This is how AMC-MECANOCAUCHO® has installed many high-performance floating floors, adapted to many design constraints.
Do not hesitate to contact us if you are interested.
United States
