Improving Sound Insulation in Party Floors

Customers often ask us how they can improve the sound insulation performance of their party floors. We have undertaken hundreds of acoustic design reviews and sound testing throughout London and the South East, so we have extensive knowledge in this area. how APT sound testing has undertaken hundreds of sound insulation tests on party floors on new build and converted properties throughout London and Greater London.

In many cases the existing floor construction is similar to the image shown below, this type of existing floor construction usually achieves 30-35dB for airborne sound and 66-74dB for Impact Sound. Obviously, these figures fall well short of the minimum requirements of Approved Document E, which requires 43dB & 64dB for precompletion sound testing, and will be extremely noisy if you are in the surrounding flats, especially if you are in the flat below.

 

Ways to improve sound insulation in floors

To improve the chance of a successful sound test and reduce the chance of noise flanking you will need to ensure that you allow for the following five acoustic design considerations, when upgrading an existing floors and walls in flats they are:

1. Improve the mass of the ceiling.
2. Isolation of materials
3. Absorption by installing acoustic wool
4. Resilience by installing acoustic underlayment
5. Add Stiffness

The main reasons for excess floor noise 

The are many reasons for party walls failing the pre-completion sound testing for Part of Building Regulations, the main reasons are

1. Where lightweight blocks used in the inner envelope construction. This allows sound to travel along the lightweight blocks both vertically and horizontally from dwelling to dwelling.
2. Bridging an acoustic floor system with skirting, or via screwing down the floor system to the joists.
3. Resilient bars missing or fitted incorrectly to the underside of the floor joists.
4. Excess recessed lights have been fitted into an acoustic ceiling.
5. The dividing floor has a lack of mass or acoustic insulation has not been installed correctly, and/or or direct fixing of plasterboard and/or floorboards to joists without using a resilient ceiling construction and/or floating floor.
6. Through Windows if they are not double-glazed units and/or have secondary glazing as a minimum – this is often a problem if there is a continuous curtain wall running through the dwellings.
7. Along structural joints along the perimeter wall and floor joint. These areas should be filled with acoustic mastic)
8. Structural steels that run through one property to the other without material isolation, i.e. plasterboard is screwed directly to the steel offering little or no noise isolation.

If it is a conversion project and you are unsure of the existing floor construction and sound insulation performance, we often recommend our ‘sample sound testing service. Firstly, we visit site and undertake sample sound testing to at least one floor partition – this usually consists of at least one airborne and impact test to party floor. Once the airborne floor sound test results are established, we can then offer a targeted acoustic design solution to achieve compliance with Approved Document E.

During the onsite construction, we can visit site to check that the construction team is installing the acoustic materials in-line with manufacturer’s guidelines, this is the third element of our acoustic service.  In our experience a sound test failure is often caused by poor workmanship rather than the actual acoustic design. The site survey helps to further reduce the chance of a test failure.

Don’t forget about noise flanking via the building structure

In many cases there are more technical issues such as noise flanking which may require more detailed diagnosis and invasive investigation. This can mean having to remove some of the wall and floor partitions. Often noise flanking is causes by the use of lightweight blocks in the construction of the walls in an apartment development. This can allow sound to travel along the walls both horizontally and vertically from dwelling to dwelling. In many cases a wall and/or floor partition may have a very robust acoustic construction; however, the floor partition will still fail due to the sound travelling up and down the walls via the noise flanking pathway.

A simple acoustic upgrade for party floors

One of the easiest solutions to improve the acoustic performance of party floors between flats, is to retain the existing joists and between the joists install a 100mm RW45 acoustic insulation. Above the joists install 22mm T&G boarding, above the boarding install a layer of 6mm acoustic resilient membrane, this must be bonded to the T&G boarding. This can then be finished with engineered flooring and/or carpet. Below the joists install resilient bars and below the bars install 2 x 15mm  layers of soundboard. All boards must be properly lapped, and the perimeter joints filled with acoustic mastic. This acoustic solution is usually robust enough to achieve the requirements of Approved Document E; however, as every project is slightly different it is always best to undertake a site-specific design review for each project.  in some instances you may only be able to apply an acoustic solution to the ceiling or floor, when this happens you often need to look at a different system that uses much more expensive acoustic material solutions.

We can help with acoustic design and sound testing

It can be very time-consuming trying to identify the cause of a failed sound test and undertake the remedial works to achieve Building Control signoff. To reduce the risk of acoustic issues on your site is always best to hire an experienced consultant. We are a UKAS accredited company, so you can be sure of a friendly and professional service providing a ‘one stop’ solution for all your acoustic requirements.

If you would like more information in regards to sound testing service and/or acoustic design services in London, please contact us on 01525 303905 or info@aptsoundtesting.co.uk, for more information please visit our website at www.aptsoundtesting.co.uk or download our sound test checklist or visit our new sound testing  blog.