Sounding out our Construction Technology Services
After cracking and water damage, complaints relating to building acoustics are more numerous than any other category of reported defect. Of reported problems, unwanted noise, particularly in multi-occupancy dwellings, is often troublesome not least because our response to noise is both subjective and subject to environmental influences.
To deal objectively with noise problems requires an understanding of the response of the human ear, knowledge of the mechanics of sound transmission and familiarity with written authority.
Unwanted sound transmission is often a symptom of other unseen defects. For example, middle to high frequency transmission through a party structure is usually symptomatic of breaches in the fire compartmentation. Proper investigation therefore considers not only the cause and resolution of the noise problem but also the other defects revealed by the acoustic properties of the construction under study.
A derelict city centre warehouse in heavy brick, iron and timber construction was converted into low cost flats. Once occupied about 2/5th of the residents complained of poor sound separation between dwellings.
The design used tried and tested acoustic systems in non-standard construction with unpredictable results.
Various crucial details were not drawn leading to site improvisation.
Investigation revealed faults which would allow flanking transmission and flawed design and workmanship which would increase direct transmission.
Conventional testing, while confirming poor sound attenuation, cannot identify the transmission routes. To assign responsibility it was necessary to devise and use new testing methods to establish the extent to which the faults originated in design and in workmanship.
Following the sound transmission routes allowed numerous faults in fire compartmentation to be traced.
Repairs were implemented and carefully recorded.
Mediation was entered into to avoid the cost of litigation and the project managers, architects and contractor each contributed to a settlement.
Structurally Born Sound Transmission
A housing association commissioned a conventional new building which gave rise to complaint of excessive sound transmission.
A study of the complaints revealed the likely cause to be structurally transmitted sound.
Limited invasive investigation revealed temporary works had been left in place partially negating the function of the proprietary acoustic flooring. Removing these to correct the floor construction overcame the problem.
The builder carried out the remedial work at no cost to the housing association to avoid litigation.
In newly built flats, the top storey of which were in the ‘attics’, complaint was made of ‘chatter’ in the roof tiles disturbing sleep.
A claim was taken to arbitration but failed because no objective evidence that the noise was excessive was put forward.
The claimants mistakenly proceeded on the understanding that tile chatter itself was a defect. In this they were wrong.
Had they measured the increase in noise caused by the chatter they most probably could have sustained a claim.
Modern roof linings, to provide high thermal resistance have low density and provide correspondingly low sound proofing. A traditional attic room with lath and plaster lining to the roof would benefit acoustically from the mass of dense plaster thus better protecting occupants from ‘building’ noises.
Understanding the behaviour of each component of a building is fundamental to correct design, thorough defects investigations, devising effective remedies and understanding how to formulate a claim which is sustainable at law.