Improving acoustic performance with seperation
I speak to architects, specifiers, contractors, clients, private developers and DIY customers every day of the week. They all ask a range of questions but the one I seem to be giving advice on more than most is the fact that separation is needed in a ceiling, floor or wall construction to improve the acoustic performance levels.
How acoustic separation works
Basically sound passes through materials. The more a construction detail is connected the more sound is likely to find it’s way through it. It is virtually impossible to make anything sound proof if there is connections so all we can do is add as much decoupling and separation as possible within an acoustic solution to break these connections and remove the direct sound paths.
Now it may sound like a difficult process, sometimes it is, however, we will never achieve any form of acoustic ratings on site if basic practices are not adhered to. Luckily Hush has a recent example where a mixture of poor information, direction connections within the construction details, value engineering and cost saving showed exactly what can happen when separation is not carried out within a separating floor construction.
You should stick to your specification
Hush was involved with a client and a contractor on a development in the North West of England. Hush created a specification with the architect that would have met the requirements of the Building Regulations for Material Change of Use. The specification was by no means over the top, it was actually as basic as it gets. The plan was for the Hush Panel 28 acoustic floor deck to be laid over the existing floorboards, the Hush Slab 100 to be used within the joists and a simple ceiling construction comprising of the Hush Bar Resilient Bars with two layers of 15mm Soundbloc fixed to the underside of them. Anyone reading this will realise that the specification, albeit standard in conversion development, is actually the minimum you could expect to get away with to show compliance with the Change of Use Standard of the Building Regs.
When it came to ordering the materials, the contractor changed from the Hush products as they thought they were getting a product of the same performance standards at a cheaper rate. This was a typical example of Value Engineering that actually reduced the performance of the construction. However, as it happens, the floor product and the insulation product may have been sufficient to pass a test as long as the ceiling detail was correct. A brain wave from the contractor occurred and they omitted the Resilient Bar from the ceiling construction and fixed the two layers of 15mm Soundbloc directly to the joists. This direct connection transferred sound easily and when the acoustic test was carried out it failed.
when all else fails
The contractor decided to come back to Hush to ask for advice. Now being a outspoken Yorkshire man I did want to tell him to go away (politely of course) but to try and stay professional we decided we would help and my Technical Manager came up with a solution to solve the problem. The solution (again simple practice) was to remove the plasterboard from the joists and install the Resilient Bars as originally specified and then re-board to the resilient bars using two layers of 15mm Soundbloc. Thinking after failing a sound test they would listen to us but we shouldn’t have been so optimistic. The contractor in their wisdom decided to ignore our advice of creating separation within the ceiling construction and decided that they would overboard the existing layers of plasterboard with another sheet of 15mm Soundbloc. What was very pleasing for Hush is when it was re-tested, the acoustic performance level actually reduced by a decibel. It had got worse. The reasons for this are because more connections were created and the ceiling became stiffer. Needless to say we didn’t hear from the contractor again after the second failed test!!!!
This incident and case study proves quite clearly that you need separation within acoustic solutions to show compliance to any sort of Regulations. Hush have the product ranges to cater for any decoupling and separation needs. If you need advice on how to achieve any UK Building Regulations Standards then please contact us on 01519332026.