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The principal aim of Research Focus is to promote the application of research in building and civil engineering.

Supported by many organisations in the British construction industry, its brief articles on current research are written for practising engineers, architects, surveyors and their clients with the objective of disseminating research news as widely as possible. Its sponsors wish to promote the benefits of research, improve contacts between industry and researchers, encourage investment by industry in research and the use of research in practice, and facilitate collaboration between all the parties involved. Formally, Research Focus is an unrestricted newsletter containing invited factual records or case studies of building or civil engineering research projects. Articles may be reproduced, provided the source is acknowledged.

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If you wish to know more about a specific project, you should contact the person named at the end of the relevant article. Look on the back page for addresses, telephone and fax numbers of the sponsoring research organisations and professional institutions. General information about their activities may be obtained from them directly.

We welcome your ideas on ways to improve Research Focus and so help it to achieve its goals. If you have a suggestion, or an article about an interesting piece of R&D, please send it to the Editor, Roger Venables, at the address below.

Editorial Advisory Panel and Editor Overall editorial policy is set by the Editorial Advisory Panel which comprises:

Chairman: Mike Thorn

Members: Prof Chimay Anumba (CICE), Terry Boniface (DTI), Ian Cruickshank (HR), Tom Harvey (BRE), Simon Lucas (DFID), Sarah Houghton (SCI), Dr Stephen Ledbetter (CWCT), Peter Lee (industry), Caroline Lilleywhite (CIRIA), Dr Martin Southcott (BCA), Dr Richard Woodward (TRL).

Editor: Eur Ing Roger Venables Secretary: Dr John Bennett (ICE).

Roger Venables, the Editor, is at Venables Consultancy, 12 Cranes Drive, Surbiton, Surrey, KT5 8AL

(020 8399 4389; fax 020 8390 9368; E-mail:

Research Focus is published by the ICE, typeset by PJM Design and produced by Thomas Telford Ltd, 1 Heron Quay, London E14 4JD. ISSN 0960 5185

© Institution of Civil Engineers, 2002

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E-mail: Research Focus is also downloadable from the ICE website ( and readable using Acrobat software.



Acoustic performance of Slimdek Acoustic performance is increasingly important in residential developments as

developers and occupants demand higher standards. The Building Regulations for such buildings include minimum standards of acoustic performance for walls and floors between dwellings, which are to be upgraded in 2002.


limdek floors and other forms of steel construction are increasingly being used in residential apartment buildings where the benefits of speed, quality and off-site prefabrication are important. To demonstrate the acoustic performance of Slimdek, SCI and Corus organised a series of acoustic tests in a residential development in Scotland, 8 storeys high and containing 49 high- quality apartments. The composite floors consist of 280 mm asymmetric Slimflor beams using deep decking with a resilient floor and suspended ceiling. The results show that Slimdek can easily achieve acoustic insulation standards considerably better than current and proposed Building Regulations. The average

75mm concrete cover


18mm thick tongued and grooved chipboard walking surface

13mm thick glass fibre quilt

45 x 45mm deep battens with integral foam strip

concrete floor slab with SD225 deep decking

single skin 12.5mm thick plasterboard suspended ceiling

The tested floor

airborne sound insulation (DnTw) was found to be 62 dB. This compares well with the minimum acceptable in the Regulations of 52 dB. The average impact sound

transmission (L’nTw) was found to be 48 dB, compared to the Regulations’ requirement of less than 61 dB. Furthermore, the test results meet the optional ‘Enhanced Acoustic Standards’ set out in a recent BRE


Legionnaires’ disease Recent research strongly indicates a link between Legionnaires’

Disease and the presence of Legionella in water systems in homes.

egionnaires’ disease is a serious form of pneumonia responsible for an estimated 1000 UK hospital admissions a year. Caused by inhaling Legionella bacteria, found in many hot and cold water systems, particularly large complex systems such as those in hospitals, hotels, office blocks and factories. But many cases are sporadic (apparently unconnected with any other case) and community-acquired – called SCA cases. It has been suggested that these SCA cases are caused by Legionella in home water systems, but this has not been established in previous research. A Government-funded project led by BRE investigated the issue. Water samples were taken from the homes of 81 sufferers of SCA Legionnaires’ disease. In 12 cases, clinical isolates of Legionella were obtained, so that the exact ‘strain’ of the organism could be determined. A water sample was also taken from 81 controls. About 10% of the 162 homes tested had Legionella in the water. About three times as


many patient homes as control homes had Legionella. In two out of the 12 cases with a patient isolate, Legionella typing showed in- distinguishable organisms in the water sample – very strong evidence that these two cases were contracted from water in the home. The research team commented that: ‘When Legionnaires’ disease is diagnosed, it would be useful to obtain water samples from the patient’s home and to collect patient isolates more routinely as part of the diagnosis. This will help to establish whether the home is the source of the illness. Apart from identifying a potential risk to other occupants and visitors at the same address, this practice will help to quantify the risks to a greater extent than was possible in our study.’

For further information please contact Professor Gary Raw of BRE (01923 664507; fax: 01923 664443; E-mail:

Research Focus NO. 48 FEBRUARY 2002

publication for developers who wish to specify a standard higher than the Regulations. The SCI and Corus plan to carry out further acoustic testing of steel frame buildings with composite floor slabs to demonstrate the high standards that can be achieved.

For further information please contact Dr Mark Gorgolewski, The Steel Construction Institute (01344 623345; fax: 01344 622944; E-mail:

softwood timber battens

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