Robust Details - The holy grail for designing multi-occupancy residential development?

Robust Details was created in December 2003 as a solution to the request from the housebuilding industry for an alternative to pre-completion sound testing whilst still fulfilling the sound insulation requirements of the Building Regulations (in England and Wales). It was implemented in 2004. The scheme was adopted for the Scottish Building Standards in 2012 but isn’t widely used in Scotland. The scheme is for new, adjoined dwellings and is not suitable for conversions, home extensions or building refurbishments. This is a common misconception in our industry as builders, contractors, builders merchants and even architects (believe it or not) do refer to Robust Details for developments that are not New Build.

Building Standards and Regulations throughout the UK, Document E (England & Wales), Part G (Northern Ireland), Section 5 (Scotland), refers to the Passage of Sound and stipulates pre-completion sound testing as a requirement to ensure the regulations are met, however Robust Details Ltd introduced this alternative construction method as a way of avoiding the requirement to test and they claim that the Robust Details building method will remove the uncertainties that pre-completion sound testing may bring.

The details are intended to give architects and builders confidence when designing and constructing separating elements (separating walls or floors) within New Build residential construction. This confidence is achieved due to the systems in the Robust Details handbook being put through a strict testing regime before they can claim to be Robust Detail Approved. Robust Details has a set of criteria that must be met before a product/system can be incorporated within the handbook and part of that criteria is for a system to achieve a minimum average acoustic rating that is a 5 dB improvement on the UK Building Regulations/Standards. This is for both airborne and impact sound transmission. The manufacturer that would like their product to be in the Robust Details handbook has to carry out 30 site tests and 5 lab tests to ensure these acoustic values are met.

When a system is accepted by Robust Details and placed in the Robust Details handbook then the system obtains a unique Robust Detail number and this number can be specified and used for construction of New Build connected construction. Systems in the Robust Details handbook include different structures such as timber frame, steel frame and masonry and they include separating floor and wall details.

Robust Details try to make the handbook user friendly and the following process is used when specifying/using the handbook: •

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The client and the design team will discuss using Robust Details building method for their development.

The design team will work out which Robust Detail systems should be used on that development.

The client will register the site and the plots with Robust Details Ltd to which Robust Details will accept or refuse to allow the development to be constructed the way the design team has specified. If accepted then the specification will be issued to the developer installing the systems.

The developer then needs to build exactly to that of the registered specification, deviations mean that the system would not be Robust Details compliant and the site would need to revert to Pre-Completion Testing in accordance with the Building Regulations/Standards.

To prove compliance when installing a Robust Detail system, a Robust Detail checklist will need to be produced and signed and given to the Building Control department overseeing the development. This is the same whether it is a LABC site or a private approved inspector. A site should not be signed off as complete until the check list is witnessed and is correctly filled out.

• When the check list is witnessed by the Building Control Officer or Approved Inspector the site can be signed off as complete without the need for any acoustic testing.


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(Our thanks to Robert Crampton, Managing Director, Hush Acoustics, for this BKE article)




Understanding the process of Robust Details is key when specifying or using the document. Although this might sound like a very obvious thing to state it is in fact the very reason that there are so many issues on Robust Details designed developments.

I need to state before I carry on with this article that I am not against Robust Details in any way. I support the idea behind it and I believe there to be a lot of good information in the Robust Details handbook. Hush have Robust Details approved products and are able to offer advice on Robust Details designed developments. I am writing this piece of text due to the complete misuse and misconception in the building industry that Robust Details is the holy grail for designing multi-occupancy residential development.

It is no doubt that Robust Details systems are used on the majority of multi- occupancy developments in the UK due to the fact that acoustic testing is not required. This is the only reason actually that it would be used. It is not a cheaper method of construction, it is not flexible to suit site conditions and it isn’t very easy to stay compliant to. The reason this construction method is so frequently used is because developers see it as a way of getting away with not doing an acoustic test on site. Actually, Robust Details systems with named products in them are far more expensive than designing solutions that are due to be tested on site before completion. It is amazing that the very reason that the document is so popular is actually the reason behind the growing epidemic that Robust Details solutions are not performing to the standards they are supposed to. If you remove the fear factor of failing an acoustic test from the developer, the attention to detail is not there to ensure things are built in the correct way. This introduces poorer building methods that reduce the acoustic performance of the building. There is supposed to be random testing carried out by Robust Details but there is nowhere near enough testers to get around all the Robust Details sites so the chance of having a random spot check is very remote. These poorer building methods are not picked up due to the fact there isn’t enough inspections and there isn’t enough testing so there are many systems being installed incorrectly throughout the UK. There is also a massive issue with product substitution to save money which means Robust Detail is not being followed correctly and therefore not compliant. These issues are not picked up until the building is being lived in and the occupiers begin to raise acoustic complaints. When these complaints are looked into, much investigatory works are to be carried out. These investigatory works are finding that not only are performance levels less than the 5dB improvement on UK Building Regulations/Standards that is required for these systems to be Robust Details compliant but the test results are falling short of the minimum requirements of the Building Regulations/Standards. This is a major concern and a major expense to put right. It has been such a concern for Robust Details that they have removed some systems from the Robust Details handbook due to constant failures.

What I believe is the answer to this issue is not to stop using the Robust Details handbook for information and to relate to but to not register it as a Robust Details site and ask the client to get acoustic testing done to prove compliance with the relevant UK Building Regulations. If a site passes a test there is no complaint that could end in costly remedial works. This solution should be adopted in my opinion until Robust Details enforce more testing to ensure things are being built correctly.

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