ANC practices can help architects assess indoor and outdoor sound and vibration levels in order to design effective and compliant insulation solutions for projects in urban settings
Members of the Association of Noise Consultants (ANC) are seeing a significant increase in enquiries from architects and builders looking to find the best way to manage noise on urban commercial-to-residential conversion projects.
ANC member David Garritt explains the key issues involved.
First steps: Establishing existing sound sources
When looking at a project overall, the first point to consider is that of indoor sound climate caused by external sources.
This needs to be accurately established through an investigation of the sources of sound at a site to quantify the existing outdoor sound climate.
The types of sound to be considered will be different if the project is permitted development or requires planning permission.
Permitted development projects may only have to consider sound from nearby commercial uses, whereas projects requiring planning approval should consider all external noise sources.
Points of reference include BS 8233:2014 (Guidance on sound insulation and noise reduction for buildings), which contains guidance on internal sound levels caused by relatively anonymous outdoor sources, such as road traffic.
ProPG: Planning & Noise also provides a recommended approach to the management of noise within the planning system in England.
If the outdoor sound climate is influenced by other sources, for example industrial premises, entertainment venues or fixed plant, then different internal sound criteria may be appropriate.
Control or mitigation at source is desirable if practicable, but this is not always possible. The site may need a BS 4142:2014+A1:2019 (Methods for rating and assessing industrial and commercial sound) survey or an assessment to the Institute of Acoustics Good Practice Guide on the Control of Noise from Pubs and Clubs 2003.
Sometimes existing window casements are retained and may require secondary glazing or, if new windows are proposed, then a glazing specification can be provided.
The method of ventilation is also important - is the site suitable for natural ventilation with windows open and trickle ventilators or is a mechanical ventilation system required?
The ANC Guide to Acoustics, Ventilation and Overheating is useful here. Approved Document O of the building regulations may also apply where there is a risk of overheating.
If mechanical ventilation is required, consideration needs to be given to internal sound levels caused by ventilation equipment and any outdoor noise impact from fixed plant units.
Trickle ventilator specification is also vital. The sound insulation of many building elevations is heavily compromised by basic ventilators that do not offer sufficient sound attenuation when open.
There may also be existing internal sources that affect the proposed development, such as from other buildings that directly adjoin the development or from existing sources in other parts of the same building.
Structure-borne sound/vibration as well as airborne sound also needs to be considered.
The results of a survey of existing sound climate can be used to assess feasibility, provide acoustic specifications for the building and inform layouts in the pursuit of good acoustic design with maximum commercial feasibility.
ANC members can investigate and quantify all factors and provide recommendations for mitigation and appropriate construction methods.
Solutions: Specifying internal sound insulation
Separating walls and floors between flats and between flats and other parts of the building must meet the minimum requirements set out in Approved Document E of the building regulations (ADE).
Depending on the use of other areas of the building, a higher minimum standard of sound insulation may be required between the spaces than quantified in this document.
Robust Details or bespoke sound insulation details for the development can be used for greater design flexibility. Sound insulation testing can sometimes be carried out prior to conversion work being undertaken to determine the existing level of performance.
Sound insulation tests are required on the completed building to demonstrate compliance with ADE.
The best way to maximise the likelihood of passing the sound insulation tests is to seek expert guidance before construction starts. ANC companies can advise on construction proposals, junction details and minimising flanking transmission.
Approved Document E states that sound insulation tests should be performed by a company with third-party accreditation, such as UKAS, or members of the ANC ADvANCE Registration scheme.
Any company that is part of the latter has demonstrated competency in undertaking the tests accurately. These companies are subject to an annual audit of a randomly selected test site and must complete periodic witness tests by an ANC examiner. Member companies can give advice on remedial treatments in the event of a test failure.
The results are uploaded to the ANC registration scheme server, where they can be checked by the customer and building inspectors so there can be no doubt as to the official result.
A more in-depth technical article on this subject can be found at association-of-noise-consultants.co.uk/conversions
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