Sound Reduction for Buildings

Providing sound reduction in buildings is an essential part of complying with current building regulations and Approved Document E. 

To achieve the required sound reduction we need to introduce elements of mass to provide suitable sound reduction performance. We also need to ensure that no gaps or weak spots within the installation are left as this will compromise the effectiveness of the solution. 
Architectural sound reduction is covered further here and additional information on sound insulation testing is available if required.

Timber Acoustic Floors

Timber acoustic flooring is available from numerous manufacturers and designed to meet various different performance standards to suit different environments and requirements.

When choosing an acoustic floor product the manufacturer should be able to provide suitable documentation showing the tested performance levels.

Unless stated otherwise by the manufacturer acoustic floors are installed as a floating floor and not fixed in place. In most instances there may be a requirement to ensure a ceiling is fitted to levels that may have formed part of the tested construction.

The structural floor or joists must be level and free from old nails or other obstructions that may affect the floor from being laid correctly. Undulations can cause the acoustic floor boards to become uneven, the glued joints fail or the final floor covering to become distorted as a result of these issues.

Acoustic timber flooring is used in a wide variety of residential dwellings or rooms including:
– New builds
– Refurbishments
– Conversions

Ensuring that suitable isolation between the floor and the walls should be used unless the manufacturer advises otherwise. An independent ceiling may also be required depending on how the manufacturer tested the product.

Depending on the type and manufacturers’ guidance timber acoustic flooring may be suitable for all applications including kitchens and bathrooms.

Some timber acoustic flooring may also be suitable for ceramic tiles, LVT and other specialist floor coverings and the manufacturers should be able to confirm any technical queries you may require. 

Overlay systems require a structural deck to be fitted in the first instance as they are not capable of supporting the loads imposed on them without assistance.

These systems may be suitable for timber or concrete structural floors and in some cases the same solution may be used on both types of structural floor types.

The majority of systems consist of two or more layers, one of which would be a flexible resilient layer.
The cheapest solutions tend to be a tongue and groove P5 chipboard layer with a resilient layer to the underside and this often provides sufficient performance to meet Approved Document E requirements.
For systems that are designed to provide additional performance levels there are a number of options that consist of 2 layers of mass and 2 layers of resilience and a typical build would be:
– MDF, P5 chipboard or other similar mass layer with a tongue and groove 
– A flexible resilient layer to decouple both mass layers
– A further mass layer of wood, cement board or similar mass material
– Final flexible resilient layer of foam, polyester or other suitable material 

Structural systems are capable of being laid direct to joist as they have been designed to accept the loads that are normally associated with floorboards that would be used on conventional floor constructions.

Care must be taken when engineered joists are being used as these normally require the floorboards to be screwed direct to the joists to help provide the structural requirements of the joist system.

These systems have been designed to provide both the performance levels and structural requirements and usually consist of 2 mass layers and 2 layers of resilience and a typical build would be:
– P5 chipboard floorboard with a tongue and groove 
– A flexible resilient layer to decouple both mass layers
– A further mass layer of wood or cement board 
– Final flexible resilient layer of foam, polyester or other suitable material 

This system comprises of the following elements:
– Platform deck such as P5 chipboard floorboard
– Timber Battens with a resilient layer to the bottom face
– A series of cradles that sit on the floor and hold the timber battens in place
– Mineral wool laid between the cradle and battens 

The cradles are fixed to the structural floor at a set distance and spacing. The battens are then fitted into the cradles without the use of any mechanical fixings.
Once the mineral wool has been placed between the battens and the floorboards fitted in place with the manufacturers guidelines. This is generally glued and screwed although any fixings must not bridge the cradle and battens by going into the floor.

Timber joist with structural deck and acoustic overlay floor
Typical standard floor with resilient bars

Concrete Acoustic Floors

Acoustic solutions for structural concrete base floors are available from numerous manufacturers and designed to meet various different performance standards to suit the different environments and requirements.

When looking at concrete floors these can be of any construction such as poured concrete slabs or block and beam, but they must have a mass of at least 365kg/m³ (according to Approved Document E)

Acoustic treatment for concrete floor types is to supply the required impact performance only.  Airborne noise is dealt with by the mass of the concrete system used.
Testing for impact noise levels must be done before final floor coverings, such as carpet is fitted.  

When choosing an acoustic floor product the manufacturer should be able to provide suitable documentation showing the tested performance levels.

Unless stated otherwise by the manufacturer acoustic floors are installed as a floating floor and not fixed in place. In most instances there may be a requirement to ensure a ceiling is fitted to levels that may have formed part of the tested construction.

Acoustic flooring for concrete applications are used in a wide variety of projects and building types including:
– New builds
– Refurbishments
– Conversions

Ensuring that suitable isolation between the floor and the walls should be incorporated unless the manufacturer advises otherwise. An independent ceiling may also be required depending on how the manufacturer tested the product.Depending on the type and manufacturers guidance timber acoustic flooring may be suitable for all applications including kitchens and bathrooms.

Solutions available may also be suitable for ceramic tiles, LVT and other specialist floor coverings and the manufacturers should be able to confirm any technical queries you may require. 

 

An underscreed is a layer of flexible material that is installed on top of the concrete base floor before the final screed layer is poured and leveled ready to accept the final floor covering.

Underscreed products are usually manufactured from recycled granulated rubber materials that have been compressed to provide a dense material (normally no less than 650kg/m³) to provide the impact resistance performance that it is designed to achieve.

Depending on the manufacturer, there will be various technical specification differences and these should be checked to ensure that the product meets your requirements.

 

Acoustic underlays are similar to the underscreed products however these have been designed to be laid on to the finished concrete floor prior to the final floor covering being fitted.

Underlay products need to be flexible and with good compression strength given the loads imposed by people, furniture etc will be imposed directly on to the material.
Suitable products are manufactured as a single layer of a flexible material, such as granulated rubber, cork or a mixture of both. Other products available may consist of two or more layers  of a resilient material such as foam or polyester and at least one mass layer to provide an effective level of sound reduction.

The manufacturer should be consulted as to suitability for your requirements including performance, floor finish suitability and compliance with building standards.

A couple of key criteria that are associated with minimum values to meet Approved Document E requirements are a material thickness of at least 4.5mm or a product that has been tested and achieves a performance level of at least ΔLw 17dB

Various products that we looked at for use on lightweight floors may also be suitable for use on concrete floors and for further assistance in identifying the products available, the manufacturers technical data should be checked for suitability.

Suitable products include the cradle and batten system as well as the composite acoustic floor boards.
In most cases a floor board is preferred as it has the least effect on reducing room height as they are usually thinner than a completed cradle and batten system.

Underscreed option (left) & Underlay option (right)

Walls and Ceilings

Mass for walls and ceilings is usually provided through the use of a plasterboard product fitted to a masonry, timber or metal frame structure.

The key requirement here is to ensure that the plasterboard has sufficient mass to provide the required performance levels.
Resilience must also be considered to ensure that the plasterboard is physically decoupled from the sub structure or framing material. 

12.5mm Plasterboard
Typical mass of 12.5mm plasterboard is around 8kg/m² and can be used on all wall and ceiling applications.

Plasterboard can be fixed direct to the masonry or framed structures or by the use of resilient bars or other similar decoupling methods. For masonry the dot and dab method can also be used.


15mm Plasterboard
Typical mass of 15mm plasterboard is around 10.5kg/m² and can be used on all wall and ceiling applications.

Ideally this thickness should be considered to meet the minimum requirement of 10kg/m² identified as the ideal minimum mass in Approved Document E.


Specialist Single Layer Boards
Alternatives to conventional plasterboard are also available from various manufacturers and include products such as Soundbloc.

Soundbloc is a plasterboard designed specifically for acoustic purposes with increased mass to reduce overall thickness.
Typical mass of 12.5mm Soundbloc plasterboard is around 10.6kg/m² which means Approved Document E requirements can be achieved without increasing the material thickness.


Specialist Multi Layer Boards
There are products on the market that are designed to increase the mass over and above what conventional plasterboard or Soundbloc achieve.
These specialist boards usually consist of two layers of a gypsum based product (similar to plasterboard) separated by a flexible layer to decouple the mass layers from one another.

These products should always be used in conjunction with heavy duty resilient bars for maximum performance levels.  

Resilient Bars are a formed metal product that acts as a spring so any acoustic energy that instances on to a surface such as plasterboard cannot be directly transmitted in to the structure.

Resilient bars can be provided in both standard and heavy duty types depending on the type of material and application they are to be used with or on.

When using resilient bars correct installation is a key factor given that issues cannot be corrected without removing the wall or ceiling linings.
The main issue encountered with poor installation is that the screws used are often too long causing the resilient hangers to be bypassed, 
The hanger should be fitted to the joist or frame using a suitable fixing, the plasterboard is then fixed to the resilient bar using a screw that is just long enough to provide a secure fix without it touching the joist or frame.
 

Where partitions are built the void should be treated with a suitable product to provide additional acoustic performance.

The mineral wool, when fitted between joists or in a frame, will help absorb the acoustic energy that passes through the floor or plasterboard materials.

Standard Plasterboard to Timber Frame
Acoustic Solution using Resilient Bars and 2 layers of Plasterboard

Other Products

Acoustic doors are available in a wide variety of materials and types. Whilst most doors will provide an element of sound reduction, acoustic doors have an increased mass and specialist seals to provide higher performance levels to suit applications such as:
– Privacy and sensitive areas such as interview and consultancy rooms
– Protect quiet areas from noisy areas
– Cinemas and entertainment venues
– Education establishments

Door types available include:
– Hinged single leaf doors
– Hinged double leaf doors
– Sliding doors

And can be manufactured from either:
– Wood
– Steel

The doors are commonly supplied as a pre-hung set meaning the door leaf and frame will have been manufactured as a set in the factory to ensure the fit and seals are correct.

Depending on the manufacture and type doorsets can be sourced to provide rating in excess of Rw 50dB

Acoustic windows are available in a wide variety of materials and types. Whilst most windows will provide an element of sound reduction, acoustic windows have an increased mass, specialist seals and design elements to provide higher performance levels to suit applications such as:
– Privacy and sensitive areas such as interview and consultancy rooms
– Protect quiet areas from noisy areas
– Music studios and recording establishments

Acoustic windows utilise a frame designed to be sealed correctly within the opening as well as:
– Increased thickness depending on design
– A minimum of two panes of glass
– Triple glazed units would have the centre pane at an angle
– The space between the panes are treated with an absorbent lining
– The glass may be thicker than normally expected

Where partitions are built the void should be treated with a suitable product to provide additional acoustic performance.

The mineral wool, when fitted between joists or in a frame, will help absorb the acoustic energy that passes through the floor or plasterboard materials.

Mineral wool density used is normally around 45kg/m³ although most manufacturers will have tested their own systems and this needs to be considered. 

Timber Acoustic Door with Vision Panel
Triple Glazed Acoustic Window
Mineral Wool to Cavity
Treatment Types

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