BS-8233-1999.pdf

| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 8233:1999 ICS 91.120.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Sound insulation and noise reduction for buildings Ð Code of practice Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 06:01:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having been prepared under the direction of the Sector Committee for Building and Civil Engineering, was published under the authority of the Standards Committee and comes into effect on 15 August 1999 BSI 08-1999 First published 1948 First revision, October 1960 Published in metric form, March 1972 Second revision, as BS 8233, August 1987 Third revision, August 1999 The following BSI references relate to the work on this standard: Committee reference B/209/18 Draft for comment 97/105886 DC ISBN 0 580 33009 5 BS 8233:1999 Amendments issued since publication Amd. No.DateComments Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee B/209, General building codes, to Subcommittee B/209/18, Sound insulation, upon which the following bodies were represented: Aggregate Concrete Block Association Association of Building Engineers Association of Noise Consultants Autoclaved Aerated Concrete Products Association BAA plc British Precast Concrete Federation Ltd. Concrete Society Consumer Policy Committee of BSI Convention of Scottish Local Authorities Department of the Environment, Transport and the Regions Department of the Environment, Transport and the Regions (represented by the BRE) Gypsum Products Development Association Institute of Acoustics Institute of Physics National House-building Council Noise Abatement Society Royal Institute of British Architects Royal Institution of Chartered Surveyors Scottish Office Ð Construction and Building Control Group Society of Chief Architects of Local Authorities Wood Wool Slab Manufacturers Association Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 06:01:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 8233:1999 BSI 08-1999i Contents Page Committees responsibleInside front cover Forewordiii Introduction1 1Scope1 2Terms and definitions1 3Symbols4 4Measuring equipment and accuracy4 5Planning and design5 6External noise sources9 7Specific types of building17 8Sound insulation in buildings and control of noise from building services25 Annex A (informative) Noise calculations30 Annex B (informative) Noise rating34 Annex C (informative) Specification of sound insulation36 Annex D (informative) Special problems requiring expert advice38 Annex E (informative) Airborne and impact sound insulation39 Bibliography48 Figure 1 Ð Normalized road traffic noise spectrum derived from BS EN 1793-3:199810 Figure 2 Ð Typical LAeqcontours around an airport12 Figure 3 Ð Average noise spectra of a jet airliner after take-off and before landing13 Figure 4 Ð Train noise spectra with mark 2 and mark 3 coaches measured at 25 m from the track centre line, in a free field, at 160 km/h and on ªgood qualityº conventially ballasted track with continuously welded rail14 Figure 5 Ð Characteristics of sound absorbing materials23 Figure A.1 Ð The addition of two noise levels31 Figure A.2 Ð Subtraction of noise levels32 Figure A.3 Ð Sound insulation of non-uniform partitions33 Figure E.1 Ð Transmission paths (via the structure) of noise originating in room 1 (diagrammatic)40 Figure E.2 Ð Indirect sound leakage paths41 Figure E.3 Ð Mass law curve42 Table 1 Ð Symbols4 Table 2 Ð Typical traffic noise levels measured about 1 m from the faõade9 Table 3 Ð Data used in the calculation of the noise level inside a room16 Table 4 Ð The calculation17 Table 5 Ð Indoor ambient noise levels in spaces when they are unoccupied19 Table 6 Ð Indoor ambient noise levels in spaces when they are unoccupied and privacy is also important19 Table 7 Ð Maximum steady noise levels for reliable speech communication21 Table 8 Ð Guide to reverberation time T at 500 Hz in unoccupied rooms for speech and music22 Table 9 Ð Typical sound insulation specification for wall separating two cinema screens24 Table 10 Ð Sound insulation of typical windows27 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 06:01:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 8233:1999 ii BSI 08-1999 Page Table 11 Ð The sound insulation of roofs28 Table A.1 Ð Standard A-weighting values (dB)34 Table B.1 Ð Noise rating values35 Table B.2 Ð Values of a and b35 Table C.1 Ð Common indices used to describe airborne and impact sound insulation37 Table E.1 Ð Sound insulation of imperforate sheet materials43 Table E.2 Ð Airborne sound insulation of walls and partitions44 Table E.3 Ð Airborne and impact sound insulation of floor constructions47 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 06:01:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 8233:1999 BSI 08-1999iii Foreword This British Standard code of practice has been prepared by Technical Committee B/209/18. It was first published as CP 3:Chapter III:1972, which was superseded by BS 8233:1987. This revision supersedes BS 8233:1987, which is withdrawn. It takes account of recent legislation and official guidance, and changes have been made to improve clarity and focus on essential information. This code of practice draws on the results of research and experience to provide information on the design of buildings that have internal acoustic environments appropriate to their functions. It deals with control of noise from outside the building, noise from plant and services within it, and room acoustics for non-critical situations. This code of practice is intended for use by non-specialist designers and constructors of buildings and those concerned with building control, planning and environmental health. The information in this code of practice follows the typical sequence of activities in building design. Clause 5 gives a general overview of the subject, and clauses 6, 7, and 8 cover specific aspects in more detail. Clauses 5 to 8 are mainly applicable to new build, while clauses 7 and 8 will also be of use where rehabilitation or change of use of an existing building is being considered. It has been assumed in the drafting of this code of practice that the execution of its provisions will be entrusted to people who, although not experts in acoustics, are appropriately qualified and experienced. Annexes A, B, C, D and E are informative. As a code of practice, this British Standard takes the form of guidance and recommendations. It should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. In particular, attention is drawn to the Town and Country Planning Act 1990 1, the Building Regulations 1991 2, the Building Standards (Scotland) 1990 3 and the Building Regulations (Northern Ireland) 1994 4. Summary of pages This document comprises a front cover, an inside front cover, pages i to iii, a blank page, pages 1 to 49 and a back cover. The BSI copyright notice displayed throughout this document indicates when the document was last issued. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 06:01:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 06:01:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 08-19991 BS 8233:1999 Introduction Noise control in and around buildings is treated in this code of practice on an objective and quantifiable basis as far as is currently possible. For many common situations, this code suggests criteria Ð such as reasonable sleeping/resting conditions Ð and proposes noise limits that will normally satisfy these criteria for most people. However, it should be borne in mind that people vary widely in their sensitivity to noise, and the limits suggested may have to be adjusted to suit local circumstances. Moreover, noise limits refer only to the physical characteristics of sound and cannot differentiate between pleasant and unpleasant sounds. Important though psychological factors may be, it is not practicable to consider them here. Attention is drawn to the fact that measures taken to control sound may also impinge on fire precautions and other health and safety requirements; all such requirements should be considered together at an early stage of the design. 1 Scope This British Standard gives recommendations for the control of noise in and around buildings, and suggests appropriate criteria and limits for different situations. These criteria and limits are primarily intended to guide the design of new or refurbished buildings undergoing a change of use, rather than to assess the effect of changes in the external noise level. It covers room acoustics for simple situations, but not the design of buildings where the acoustics are critical, such as auditoria. This code of practice does not cover vibration control, except where it is evident in the form of radiated sound. 2 Terms and definitions For the purposes of this British Standard, the following terms and definitions apply. 2.1 sound pressure p root-mean-square value of the variation in air pressure measured in pascals (Pa), above and below atmospheric pressure, caused by the sound 2.2 A-weighted sound pressure pA value of overall sound pressure, measured in pascals (Pa), after the electrical signal derived from a microphone has been passed through an A-weighting network NOTEThe A-weighting network modifies the electrical response of a sound level meter with frequency in approximately the same way as the sensitivity of the human hearing system. 2.3 sound pressure level Lp quantity of sound pressure, in decibels (dB), given by the formula: Lp= 10 log10(p/po)2 where pis the root mean square sound pressure in pascals (Pa); pois the reference sound pressure (20 mPa) NOTEThe range of sound pressures for ordinary sounds is very wide. The use of decibels gives a smaller, more convenient range of numbers. For example, sound pressure levels ranging from 40 dB to 94 dB correspond to sound pressures ranging from 0.002 Pa to 1 Pa. A doubling of sound energy corresponds to an increase in level of 3 dB. 2.4 A-weighted sound pressure level LpA quantity of A-weighted sound pressure, given by the following formula in decibels (dBA): LpA= 10 log10(pA/po)2 where pAis the A-weighted sound pressure in pascals (Pa); pois the reference sound pressure (20 mPa) NOTEMeasurements of A-weighted sound pressure level can be made with a meter and correlate roughly with subjective assessments of loudness, and are usually made to assist in judging the effects of noise on people. The size of A-weighting, in 1/3 octave bands, is shown in annex A (see A.5). An increase or decrease in level of 10 dBA corresponds roughly to a doubling or halving of loudness. 2.5 percentile level LAN,T A-weighted sound pressure level obtained using time-weighting ªFº, which is exceeded for N % of a specified time interval EXAMPLE LA90,1his the A-weighted level exceeded for 90 % of 1 h. Percentile levels determined over a certain time interval cannot accurately be extrapolated to other time intervals. Time-weighting ªFº or ªSº can be selected on most modern measuring instruments and used to determine the speed at which the instrument responds to changes in the amplitude of the signal. Time-weighting ªFº is faster than ªSº and so its use can lead to higher values when rapidly changing signals are measured. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 06:01:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 BSI 08-1999 BS 8233:1999 2.6 equivalent continuous A-weighted sound pressure level LAeq,T value of the A-weighted sound pressure level in decibels (dB) of a continuous, steady sound, that within a specified time interval, T, has the same mean squared sound pressure as the sound under consideration that varies with time, given by the formula: LAeq,T= 10 log10 dt 1 T 0 T pA 2(t) p0 2 where pA(t)is the instantaneous A-weighted sound pressure in pascals (Pa); pois the reference sound pressure (20 mPa) NOTEEquivalent continuous A-weighted sound pressure level is mainly used for the assessment of environmental noise and occupational noise exposure 5. 2.7 sound exposure level LAE level of a sound, of 1 s duration, that has the same sound energy as the actual noise event considered NOTE 1The LAEof a discrete noise event is given by the formula: LAE= 10 log10 dt 1 t0 t1 t2 pA 2(t) p0 2 where pA(t)is the instantaneous A-weighted sound pressure in pascals (Pa); t22 t1is a stated time interval in seconds (s) long enough to encompass all significant sound energy of the event; pois the reference sound pressure level (20 mPa); tois the reference time interval (1 s) NOTE 2LAEis also known as LAX(single-event noise exposure level). 2.8 rating level LAr,Tr equivalent continuous A-weighted sound pressure level of the noise, plus any adjustment for the characteristic features of the noise NOTEThis definition is used in BS 4142 for rating industrial noise, where the noise is the specific noise from the source under investigation. 2.9 free-field level sound pressure level measured outside, far away from reflecting surfaces NOTEMeasurements made 1.2 m to 1.5 m above the ground and at least 3.5 m away from other reflecting surfaces are usually regarded as being free-field measurements. To minimize the effect of reflections the measuring position should be at least 3.5 m to the side of the reflecting surface (i.e. not 3.5 m from the reflecting surface in the direction of the source). Estimates of noise from aircraft overhead usually include a correction of 2 dB to allow for reflections from the ground. 2.10 fac Ëade level sound pressure level measured 1 m to 2 m in front of the faõade NOTEFaõade level measurements of LpAare usually 2 dB to 3 dB higher than corresponding free-field measurements. 2.11 noise rating (NR) graphical method for rating a noise by comparing the noise spectrum with a family of noise rating curves NOTENoise rating is described in annex B. 2.12 sound reduction index R laboratory measure of the sound insulating properties of a material or building element in a stated f