What will your building control surveyor look for during a plan check?

What will an inspector look for on-site?

And most importantly what do you need to do to meet the mandatory requirements?

At the recent LABC Policy Conference, we (LABC Acoustics) spoke on the importance of adopting a more proactive approach to identifying and resolving noise failures before they become an issue.

Something we encounter regularly at LABC Acoustics, is the cause of comments like:

“Why have I failed the sound test? Building Control approved my plans!”

“All the works were inspected throughout the build and the surveyor didn’t mention that there would be a problem”

As a builder or developer, you may have had the same problem where you thought you had done all you needed to do, so how did the problem arise and how could it have been avoided?

One possible cause is something that we deal with often – the incorrect specification of individual components, on architects’ plans. These errors might then be missed at the plan checks stage thus leading to sound insulation problems later.

The best laid plans…

Following building control checks, and approval, you could be forgiven for thinking that all is well. You might install the specified materials in good faith only to find later that what is deemed to provide a ‘reasonable resistance to sound’ still gives rise to complaints after occupancy.

By then it’s too late and fixing the problem becomes a costly exercise for you and disruptive for the occupants.

So what can you do to avoid these issues in the first place?

It is important to get an acoustics specialist on board at the earliest opportunity to ensure that the sound insulation testing regime is correctly adhered to and that the specified solutions really do fit the bill.

Knowing your dB(Rw) from your dB(DnTw)

One illustration of a situation where a specified solution went awry, was an architect who had specified a party wall solution on a building control application to achieve ‘airborne sound insulation of dB(Rw) 43dB’.

The problem in this instance was that dB(Rw) is a measure of acoustic performance in relation to a particular structure, material or product, as measured in a laboratory test. Although it provides a useful indication when comparing products, it doesn’t give a real-world indication of how well those components would perform as part of a completed building.

dB(DnTw) is the important specification as used in on-site testing and, combined with the spectrum adaptation term (Ctr), would give the expected acoustic performance of the party wall ‘in situ’.

In reality, the specified party wall would not have offered the required sound insulation performance when installed on site and would have failed the required tests. Meaning those walls should not have been recommended for construction.

Sound tests will be required by your local authority building control team in accordance with Approved Document E. To avoid similar issues, and potentially costly fixes, it’s important to get your sound tests conducted as early as possible.

The sooner you can get an acoustics specialist involved on even the simplest of projects, the less likely it is that there will be a problem with acoustic performance in the long run.

For more information please view the full presentation on the LABC Website.

By Dave Riley
National Business Manager

LABC Acoustics