- Basic principles of acoustics
- The different techniques of sound insulation
- The most used insulation materials to protect against noise
- The new acoustic regulation
Where the air passes, the noise passes! While nearly 40% of the French population claims to suffer nuisance, the sound insulation of housing seems essential for the comfort of its inhabitants. This makes it possible to reduce or eliminate the propagation of indoor or outdoor noise. To do this, there are different materials adapted to each situation.
Basic principles of acoustics
In order to find solutions to fight noise by isolating one's home, it is essential to determine the nature of the problem.
Thus, in acoustics there are three types of noise: airborne noise, impact noise (or solid) and equipment noise. Airborne sounds (television, discussion, music); correspond to a vibration of the air, they can be internal or external and pass under the doors and the interstices. As for the impact noises, it is noises coming from the outside that spread through the structure of the building (falling or moving objects, shocks of heels, passage of the metro...). Finally, as their name suggests, equipment noises come from household appliances such as boilers, computers or even ventilation.
Namely that according to the law of the masses, the more a material is heavy and the more it attenuates the transmission of sound waves. So by doubling the thickness of a partition, you can earn a few decibels. However, not all constructions allow it. In addition, the principle of the law mass spring is based on the interposition between two masses (original wall and plasterboard for example) of a spring element: air or flexible insulation. Here the sound waves are absorbed by the spring, which transmits them to the second mass. Systems using this principle are both lightweight and more efficient, so they allow a gain of 6 to 8 dB.
The different techniques of sound insulation
Walls and partitions can be insulated with ready-to-use glue board, metal frame and plasterboard insulation or masonry wallboard. In addition, floors are insulated with: the laying of a covering (thick carpet, floating floor), or with a floating slab, that is to say a layer of insulation covered with a reinforced concrete slab uncoupled from the walls, either with a false ceiling on a frame where the insulation is incorporated. Finally, the windows can be isolated by placing joints at the joinery to make them more watertight or better by replacing the windows with asymmetrical double glazing or reinforced insulation glazing.
The most used insulation materials to protect against noise
Glass wool, which is a low-conductive fiber at the phonic level, seems suitable for sound insulation. Indeed it displays a good sound absorption capacity in low thicknesses. In addition, rockwool has the ability to absorb sound, but also significantly reduce the impact noise. Finally, the composite polyurethane foam also offers excellent sound insulation, coupled with great lightness.
The new acoustic regulation
This regulation applies to all new dwellings whose building permit dates from after January 1996. Its purpose is to fight against noise pollution and to control housing once it is finished. For example, single-family homes must be isolated from outside airborne noise (plane, train, road), while detached houses must be isolated from airborne noise and impact noises that can be transmitted from one dwelling to another. In addition, the constraints are the same for collective residential buildings. Moreover, since 2000 the acoustic regulation is reinforced. Thus, there is a strengthening of acoustic insulation between dwellings, including common areas and outbuildings, but also a minimum isolation of the facades of 30 dB against external noise, a maximum level of impact noise from 70 to 65 dB and the limitation of equipment noise in main rooms and kitchens.
Finally, if it is done by a professional, the acoustic insulation of a home gives right to a tax credit ranging from 20 to 40%.