RBA Acoustics

How Building Regulations Could Be Improved

RBA Acoustics were recently asked to provide a written account of how we feel building regulations could be improved. This piece has since been featured in the ADF magazine.

Here at RBA Acoustics, we spend a considerable amount of time offering our professional interpretation of Building Regulations requirements (specifically with regard to Part E, Resistance to the Passage of Sound, of course), whether that is reporting results of sound insulation testing to demonstrate compliance to Building Control, or expectation management of occupants who are either quite justifiably upset at being able to hear the most intimate details of their neighbours’ lives, or those who believe they are entitled to live in a “sound proof box” and complain about being able to hear their own washing machine (not a joke).

That latter point ties in with a phrase we often find ourselves uttering which is that Building Regulations are minimum standards and not inaudibility standards. They’re not perfect, and in reality they can’t be, but maybe they could be better? The issues are: they have to offer occupant protection but also be reasonably achievable, both practically and economically. They have to be standardised and demonstrable but also not so complicated or technical that no-one understands them. They should ideally tie-in with occupant subjectivity, but everyone is different with a wide range of expectations. Therefore, at RBA Acoustics we have often strived to expand on the minimum by proposing a higher performance standard to improve occupant comfort while still keeping an eye on what is actually practically possible, and of course what is reasonable to expect. I like to call this a “grown up approach”. Assessment methodologies like Code for Sustainable Homes or the Home Quality Mark have helped us tie our recommendations on acceptable guidance, but are we still hanging these recommendations on a baseline that is fundamentally flawed?

The current Approved Document E (ADE) criteria are very familiar to many as the “pass or fail” standards, and the procedures for demonstrating these through field measurement and analysis are well established and repeatable among acousticians (in most circumstances). However, it’s not always that simple. The Building Regulations Part E Requirement E1 simply asks for “reasonable resistance” and the ADE criteria are considered “the normal” way of satisfying this. Plenty of room for interpretation there then. Many acousticians have a story to tell about a dot and dabbed solid block wall or a curtain walling installation which ends up “passing” ADE due to the way the calculation works, but you can clearly hear your neighbour talking – arguably not “reasonable”. That suggests we can’t just rely on a single number to define what is “reasonable”

But what can we actually do to improve it? We have to have some numbers to work with, but perhaps there should be better guidance on how to interpret them. The current version of ADE introduced a low frequency correction (Ctr) to the performance criterion, the thinking at the time being that this accounted for modern entertainment systems. But field tested Ctr can be difficult to predict, it’s very sensitive to frequencies which are very difficult to measure accurately, and it doesn’t do anything to help with hearing your neighbour’s voice! Is Ctr an unnecessary complication that should be removed from a future version of ADE? Would it be more useful to provide guidance on interpreting the shape of the sound insulation graph as well as the single number quantity?

RBA have recently been involved in complaints of occupants hearing excessive low frequency impact noise from above where the tested performance is 20dB better than the ADE criterion – again, the subjective response doesn’t match up with the objective test result. There is currently no Ctr-equivalent correction for low frequency impact sound insulation. Should there be? Would it help or would it offer another layer of complication that could again still be misinterpreted?

Let’s not forget that a lot of things such as noise from doors banging, light switches and various other structureborne noise issues are not currently covered by Part E, nor is a consideration for how quiet your flat is and therefore how much more noise you can hear which would otherwise be masked by traffic noise in a more urban area. RBA employees have spent many an evening measuring noise from soil vent pipes on behalf of disgruntled occupants who have been offered an unwanted insight into some of their neighbours’ more intimate habits. Perhaps efforts should be focussed on how to clearly incorporate these common areas of complaint?

RBA are currently heavily involved in the Association of Noise Consultants working group on proposed improvements to ADE, and can draw on many years’ experience of field testing and discussion points similar to those outlined above. For now I think we’re a long way off deciding on what the right answer should be, but at least we’re talking about it. An old boss of mine always used to say that acoustics was the last thing anybody ever considers, but the first thing people complain about. Hopefully we’ll continue to get further and further away from using such statements.

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