Solving a stud wall flanking issue in a residential property, East Sussex

A residential developer approached Hush Acoustics after an acoustic test conducted on their project in St Leonards on Sea failed to achieve the acoustic compliance level needed under Approved Document E of the Building Regulations.

The problem stemmed from a separating wall between two bedrooms which was constructed using a timber stud wall and had an overall thickness of 170mm. Its acoustic design was adequate on paper, but there was one issue that had not been correctly treated.

One of the rooms measured 37m3 and the other 29m3 in size, with one notable consistent feature being a screed laid over a concrete floor.

An airborne sound insulation sample test was carried out with no floor covering in place and this revealed a result of DnTw+Ctr 31dB.

Levels of ‘flanking’ sound were significant - this meant sound was passing under the separating wall via the floor screed. The solution proposed by Hush Acoustics was to install Hush Mat 15 over the screed floor in both rooms.

The effectiveness of this solution was evident in the follow-up test result of DnTw+Ctr 44dB. Whilst this result would be regarded as an average performance in most other types of buildings, the improvement here from a poor DnTw+Ctr of 31dB to 44db showed that Hush Mat 15 had delivered significant improvement and provided a solution to flanking transmission sound sources.

The ensured the residential development satisfied the requirements of Approved Document E.