“Very proactive and extremely helpful, especially with technical queries. I would not hesitate to recommend and will certainly be using them again in the future.”



Under CDM2015 regs we have found CASS ALLEN to exercise a level of professionalism and due diligence which is second to none. We would therefore definitely recommend CASS ALLEN as our preferred acoustic consultant, for all of our projects.’


SF - Taylor Wimpey South Thames

“I was very pleased with their technical knowledge and professional approach when dealing with a very awkward purchaser as well as the local authority.”


JH, Telford Homes

“Cass Allen went above and beyond to help with the Acoustic planning performance and conditions regarding the Greenwich Creekside project…”


LM, Capita plc

“Good comprehensive reports and advice at all design stages. Very flexible and professional, provided attendance at acoustic cladding tests at short notice.”


DF, Berkeley Homes

“Cass Allen have assisted us on a number of our projects. I’ve been impressed with their thorough and professional approach.”


MT, Lark Energy


In February 2015 updates to BB93 were published setting out minimum performance standards for the acoustics of school buildings.

 What has changed?

  • BB93 now only contains performance standards, with very little design guidance. Additional design guidance will be issued separately in due course by the Association of Noise Consultants (ANC) and the Institute of Acoustics (IOA).
  • Performance standards have now been introduced for refurbished school buildings.
  • The performance standards now apply to rooms with their normal furnishings instead of empty rooms. This is more representative of the situation that will exist when the school is operational, but does introduce uncertainty regarding the acoustic performance of the fixtures and fittings.
  • There is a performance standard for rain noise on roofs. This means that polycarbonate roof lights and lightweight roofs are unlikely to be acceptable in teaching areas.
  • The performance standards for indoor ambient noise levels have been clarified for different rates of ventilation for air quality and thermal comfort. In particular, there is a new upper noise limit of 55 dB(A) for external noise ingress when open windows are used to control overheating. This means that it will be possible to use openable windows to control overheating in schools in noisier areas than was possible under the previous version of BB93.
  • Common situations that previously required Alternative Performance Standards (APSs) are identified, and pragmatic performance standards for these situations are given. These include:
    • Doors connects teaching spaces
    • Movable walls
    • Vision panels between music rooms, multi-purpose halls and control rooms
    • Serving hatches between kitchens and multi-purpose halls
  • There was previously no guidance on how far APSs could deviate from the performance standards in BB93. The limit for APSs is now set at the performance levels for refurbished buildings.
  • There are more requirements for pupils with special educational needs.
  • The performance standards for reverberation levels in indoor sports halls has been relaxed for larger sports halls.

 Here are some of our most recent BB93 projects


We are here to help…….

If you have any queries on the new document and how it may affect your projects – please do not hesitate to call us on 01234 834862.


Get in touch

We hope you’ve enjoyed browsing our website but if you have any questions feel free to call us to talk through any acoustic issues you may be facing on your projects. The best person who can help with specific queries can be found here.