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ALL ABOUT SOUND INSULATION

sound insulationMany people think that noise pollution is a stress factor. To protect themselves and also preserve the neighborhood noise from the housing, there are different sound insulation solutions suitable for walls, floors, and ceilings.

  1. What is sound insulation?

Sound insulation (or acoustic insulation ) aims to reduce or eliminate the spread of noise inside or outside the home. For this, we use products different from those used for thermal insulation.

The choice of materials and the insulation technique involve becoming familiar with the basics of acoustics.

Classification of noises

  • aerial

Interiors or exteriors, they pass through the doors, through the interstices of the windows, shutter boxes …

  • Impact (or solidiens)

Noise outside the room or dwelling, propagating through the structure of the building (falling or moving objects, shocks heels, subway …).

  • Equipment: boiler, piping, ventilation …

Mass and mass-spring-mass laws

Mass law

The heavier a material is, the more it reduces the transmission of sound waves . Thus, at equal thickness, a single concrete wall better protects airborne noise than hollow brick or plaster tile.

By doubling the thickness of the wall, an acoustic loss of 5 to 6 dB is achieved.

Disadvantage: all constructions do not allow it (heavy overload, need to strengthen the foundations …).

Mass-spring-mass law

The principle is based on the interposition between two masses (original wall and plasterboard for example) of a spring element: air or flexible insulation.

Sound waves create vibrations through the existing wall. They are absorbed by the spring, which transmits them amortized to the second mass.

Systems using this principle are both lightweight and more efficient: gain of 6 to 8 dB.

Good to know: the sound is a pressure wave characterized by its intensity (in dB), its frequency (in Hz) and its duration.

  1. Sound insulation: walls, floors, and windows

Sound insulation of walls and partitions

Ready-to-use sandwich panels, ep. 4 to 10 cm

– Easy installation by glue pads.

– Plasterboard facing.

Insulation on metal frame and plasterboard

– Insulation reinforced by an air gap between the profiles and the existing wall.

– Can be applied to walls and ceilings.

Masonized bulkhead

– Insulation simply placed on the original wall and concealed by a partition made of brick, cellular concrete or plaster tiles.

– Unbundling of the frame by an elastomeric strip.

Sound insulation of floors

Laying a covering: thick carpet, floating floors …

Floating slab: insulating layer covered with a reinforced concrete slab, separated from the walls.

– Heavy site but high acoustic performance.

– Extra thickness requiring sufficient ceiling height and, often, the cutting of the doors.

False ceiling on the frame with an incorporation of an insulator.

Sound insulation of windows

The good condition of the carpentry is essential.

– Disjointed chassis leave gaps (phonic bridges) through which airborne noise is infiltrated.

– The installation of joints can be, in this case, a solution.

The glazing is as decisive as the material of the structure (aluminum, wood or PVC).

– The classic double glazing (4-6-4 or 4-12-4) provides a more thermal insulation than acoustics.

– Asymmetrical double glazing (type 10-6-4) is more efficient: insulation of about 35 dB.

– The reinforced insulation glazing (VIR) is even more efficient: 40 dB.

Good to know: the installation of new windows gives the right to a tax credit on the price including tax (excluding implementation). Tenants and owners can benefit from certain conditions. The credit only concerns principal residences completed for at least 2 years.

  1. Insulating Materials

 Glass wool

Excellent sound absorption capacity in small thicknesses.

Particularly suitable for acoustic correction.

 

 Rockwool

Provides both thermal insulation and acoustic comfort.

Absorbs sounds perfect.

Significant reduction of impact noise.

 Polyurethane composite foam

Very good thermal performance, good sound insulation.

Great lightness.

 

  1. New Acoustic Regulation (NRA)

It applies to all new residential buildings whose building permit was filed from January 1996.

Objectives of the NRA

Evaluate insulation measurements (in dB).

Check the housing once the work is done.

Detached house : only subject to external airborne sound insulation (airplanes, rail, and road traffic …).

Semi-detached, terraced or strip houses: insulation against external airborne noise, and air and impact noise transmitted from one dwelling to another.

Good to know: the constraints are the same for collective housing.

New provisions of the NRA

They concern buildings whose application for a permit was filed as from 1 January 2000.

Reinforcement of acoustic insulation between dwellings, including common areas (traffic arteries) and outbuildings (garages …).

Minimal insulation of 30 dB facades against external noise.

The maximum level of impact noise from 70 to 65 dB.

Limitation of equipment noise in main rooms and kitchens.

Good to know: for facades facing classified tracks (prefectural order), the minimum attenuation is raised to 35 dB and can reach 45 dB.

Rating indices

European regulations now govern acoustic performance measurements. This results in a new calculation mode, with a single evaluation index for each type of noise, and shape modifications.

Noise categories

Buildings are classified according to their exposure to noise from land transport infrastructure. There are 5 levels, from 1 to 5, with 1 being the highest level at 81 dB. It is the prefect who ratifies by decree the sound classification of infrastructures.

Good to know: exit the old units of measurement in dB (A). The new regulation retains only the dB. However, the equivalences differ according to the sound sources.

Examples:

– 58 dB = 65 dB (A) for impact noises,

– 54 dB (A) pink = 53 dB for indoor airborne noise ….

Quantify the noise

The sound level is measured on a scale of 10 to 130 dB.

The sound reduction index characterizes the sound performance of a building element (wall, floor, door …). But, be careful, the decibels do not add up.

A loss of 3 dB actually corresponds to the division of the sound pressure by two.

The human ear is not objective, to have the impression to hear three times less noise, it is necessary to reduce the sound pressure of 10 dB.

Good to know: about 80% of the noise comes from transport. The “very noisy” threshold is above 70 dB.

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