Sound Insulation Testing - How to Pass!
Building Regulations Approved Document E Testing - tips from the acoustic experts
Sound Insulation Testing to Approved Document E is required under Building Regulations for new build or converted dwellings. It can be a confusing process – so how do you give yourself the best chance of passing the test?
Sound testing has two main assessments – airborne noise and impact noise. Both tests are required for separating floors, while only airborne tests are required for separating walls.
Sound Test Basics
The first thing to consider to improve your chance of success is to ensure that the premises is actually ready for testing. For example, all separating floor and walls should be complete, with any gaps filled and made good. Sockets should be fitted, as should internal doors (with a good seal to help improve performance). These are things which should be checked towards the end of the project – but what can be done at the design stage?
Floor Sound Testing
In general, good sound insulation performance relies upon mass, isolation and, for floors, resilience. For floors, it is generally advisable to introduce a level of isolation between the upper floor deck and the lower ceiling structure. This can be done with an independent ceiling system (where the floor sits on one set of joists and the ceiling is hung from an independent frame underneath).
Another option is the use of resilient bars, which are fixed the underside of the floor joists. These have a flexible profile which acts as a spring to isolate plasterboards which are fixed to them. These can work well, but there is a risk of bridging if they are not installed carefully.
Making the ceiling up of a high-mass construction will also help once some form of isolation is in place. This is generally achieved with a double layer of high-density plasterboard (usually 1no Fireline and 1no SoundBloc plasterboard).
Once there is a cavity between the floor deck and the ceiling structure, there will be an acoustic resonance which is defined by the cavity depth. Usually, with most constructions, this will be in the low frequency range. In order to control this resonance, acoustic insulation must be installed within the cavity to maximise the low frequency sound insulation performance.
Impact Sound Insulation
In order to achieve the sound insulation impact test requirements, some form of resilience is required within the floor deck. This effectively cushions the impact noise and prevents structure borne noise from transferring through the floor / ceiling system. Generally, this is provided by a floating floor system (effectively felt-backed chipboard) or a resilient layer (usually a rubber and foam construction). These materials also add mass to the structure, which also helps to improve the airborne sound insulation performance.
Flanking Noise
The other consideration which needs to be taken into account is flanking transmission. This is when sound passes from adjacent rooms, but not via the separating wall or floor. This could occur via flaking walls, over or under separating walls. It is important to consider flanking early in the design stage so that it can be effectively treated.
The advice above is very broad and generalised, and we would always suggest that a specific design specification is created for each and every development. As each development is unique, there will be specific requirements and challenges which need to be overcome to gain a pass under Approved Document E. The advice within this blog post should therefore be taken for illustrative purposes only.
If you would like to discuss an acoustic design project with us, then more information can be found here.
Alternatively, if you are interested in out Sound Insulation Testing services, then please feel free to contact us.
NCSL Acoustic Consultants are corporate members of the Institute of Acoustics, you can find more details on the IOA website here.
NCSL are able to help at all stages of a noise impact assessment, from initial acoustic planning to noise assessment and finally to mitigation measures where required. If you require any further information, check out our Noise Impact Assessment page or feel free to contact us.