Sound insulation design can be affected by a number of variables. Perhaps the greatest risk to good design is well meaning builders or developers who ‘tweak’ a design to fit their requirements. The example above was detected during a routine site visit, the problem (if you havent spotted it) is that the builder has fixed the two independent stud partitions together. The original specification was twin independent acoustic metal framed systems, and during the site visit an un-tested system had been substituted (which test data could not be provided) and an independent wooden stud system had been added. Worst of all the independent frames had been braced together!
Had this wall been finished, plasterboarded and sound tested then it was very likely to result in a failure and the remedial treatment would have been the removal of the wall and replacement with the original designed system to achieve the required performance. Good acoustic design and site visits from acoustic consultants at key stages of the project is paramount in ensuring that the designed building will perform as expected once tested.
A similar sound testing failure occured recently when a developer had braced an independent ceiling system using joist braces. We had provided a specification at early stages of the project and inspected the independent ceiling prior to plasterboarding. At the very last stage the developer added a couple of braces (even though the ceiling had a relatively small span) as he was concerned about the weight of the plasterboard – unfortunately he failed to mention to us that he was doing this!
We also have evidence of a reduction in sound insulation performnce from a developer who decided to move away from the acoustic design of a party wall and added additonal materials into the core of the wall to ‘improve the sound insulation’. This only helped to increase the number of resonant cavities within the wall space and the developer created a wall that performed less well but cost significantly more in materials and labour. Stick to the plan – we do know what we are doing!
For more information then contact us and see how we can assist with your project design and build.