Acoustics regulations

This article examines the UK acoustic requirements for residential and non-residential buildings. This includes regulatory requirements, where applicable, but also sector specific documents such as Building Bulletin 93 for schools and the Health Technical Memorandum HTM 08-01 for hospitals. The focus is on the requirements that are influenced by the structural form and construction details rather than internal finishes and building services.

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The following types of buildings are included:

• Residential
• Schools
• Hospitals
• Commercial buildings.

Residential buildings

Steel framed residential development

The acoustic requirements of residential buildings are normally given in national building regulations and associated guidance documents. For England, acoustic performance requirements are given in Part E of the Building Regulations 2010 and in Approved Document E.

It should be noted that this document was updated in 2015. The updated document applies to building work carried out on excepted energy buildings in Wales as defined in the Welsh Ministers (Transfer of Functions) (No. 2) Order 2009. Apart from this exception, for the time being, Wales will continue to use the Approved Document E 2010 edition).

Similar equivalent documents exist for use in Scotland and Northern Ireland.

Part E of the Building Regulations

The full scope of Part E covers:

• Acoustic insulation of separating walls and floors between newly built dwellings, and dwellings formed by a material change of use.
• Acoustic insulation between hotel rooms, boarding house rooms, and other rooms used for residential purposes such as student halls of residence and key worker accommodation, formed by new-build or by a material change of use.
• Acoustic insulation between rooms within a dwelling formed by new-build or by a material change of use.
• Acoustic characteristics of common parts of apartment buildings.
• Acoustic characteristics of schools. Comprehensive guidance on requirements and ways of meeting them is covered by Building Bulletin 93.

Requirement E1 relates to separating walls and floors , and their junction details. The other regulations in Part E refer to surface finishes, internal, i.e. non-separating, walls and other building types. Requirement E1 states:

E1: Protection against sound from other parts of the building and adjoining buildings

Dwelling-houses, flats and rooms for residential purposes shall be designed and constructed in such a way that they provide reasonable resistance to sound from other parts of the same building and from adjoining buildings.

Sources of noise (from BB93)

Rooms for residential purposes, as referred to in requirement E1, include rooms in hotels, hostels, boarding houses, halls of residence and residential homes, etc. but do not include rooms in hospitals, or other similar establishments, used for patient accommodation.

Approved Document E provides guidance on how the Regulations may be satisfied and sets acoustic performance standards. The required levels of insulation to airborne and impact sound are summarised in the following tables.

Airborne sound insulation requirements (from Approved Document E)

Building type	Element	Airborne sound insulation performance (dB)
Purpose built: Dwelling houses and flats	Separating walls	DnT,w + Ctr ≥ 45
	Separating floors and stairs	DnT,w + Ctr ≥ 45
	Internal wall	Rw ≥ 40
	Internal floor	Rw ≥ 40
Purpose built: Rooms for residential purposes	Separating walls	DnT,w + Ctr ≥ 43
	Separating floors and stairs	DnT,w + Ctr ≥ 45
	Internal wall	Rw ≥ 40
	Internal floor	Rw ≥ 40

Notes:

• D_nT,w is the standardised weighted sound level difference
  
• C_tr is a spectrum adaptation term
  
• R_w is the weighted sound reduction index
  

Impact sound insulation requirements (from Approved Document E)

Building type	Element	Impact sound insulation performance (dB)
Purpose built: Dwelling houses and flats	Separating floors and stairs	L'nT,w < 62
Purpose built: Rooms for residential purposes	Separating floors and stairs	L'nT,w < 62

Note:

• L'_nT,w is the standardised weighted impact sound pressure level

The C_tr spectrum adaptation term is used to take account of low frequency sounds, e.g. traffic and bass music. The value of C_tr is negative and is typically in the range of -4 to -16 dB.

Demonstrating compliance

Acoustic testing equipment

Approved Document E describes two methods of demonstrating compliance with Part E of the Building Regulations; pre-completion testing (PCT) and by use of http://www.buildingconsents.com/Documents/robust-details-handbook Robust Details (RDs).

PCT is carried out on-site and the onus is on the builder to demonstrate compliance. It is recommended that 1 in 10 of each type of construction detail is tested. PCT only applies to separating walls and floors and is not necessary for internal walls and floors. PCT should be carried out when the rooms either side of the separating element are essentially complete, except for decoration. Tests are generally required to be carried out without non-permanent decorative floor coverings, e.g. carpet, laminate flooring, vinyl. In some cases integral soft floor coverings are permitted, provided the floor covering is glued to the concrete slab below.

Robust Details were developed as an alternative to PCT. A range of details has been developed which have been proved through testing to consistently satisfy (and exceed) the acoustic performance requirements specified in Approved Document E. The available RDs and their specification requirements are given in the Robust Details Handbook published by Robust Details Limited. To use a Part E Robust Detail in the construction process, builders must first obtain permission from Robust Details Limited and pay the requisite fee for each dwelling. Provided that the Robust Details are built correctly, this will be accepted by Building Control Bodies in England and Wales as evidence that the homes are exempt from PCT.

Examples of steel Robust Detail constructions for walls and floors have been developed.

Wall and floor constructions that, when built correctly, should provide the required acoustic performances, are provided in Approved Document E. However, these are generally conservative solutions and also still require PCT to be carried out.

Both methods of compliance (PCT and RDs) can be used for steel construction, although pre-completion testing is probably the most appropriate because it allows more flexibility in the design and detailing. The scope of the current range of RDs for steel construction is not sufficient to include all the junction details that are typically present on a residential development. Therefore, even if RDs have been used there will usually be some junctions where building control could request site testing. The range of RDs is continually growing so over time there will be fewer instances where RDs cannot be used. The approval process for new RDs requires significant amounts of site test data for similar details, for the tests to show that the details exceed the Building Regulation requirements by 5 dB on average and for the details to become public. Hence, there is often little incentive for system suppliers to share their information if they are satisfied with the results obtained from PCT.

RDs can also be used in Scotland. In Northern Ireland compliance can be achieved either by adopting specified constructions or by testing to show that non-specified constructions meet the required performance standards.

Schools

Building regulations for England and Wales

Circulation space at The Business School, Bexley

In both England and Wales, the Building Regulations provide the following requirements for acoustic performance of school buildings.

Acoustic conditions in schools

E4

1. Each room or other space in a school building shall be designed and constructed in such a way that it has the acoustic conditions and the insulation against disturbance by noise appropriate to its intended use.
2. For the purposes of this Part - 'school' has the same meaning as in Section 4 of the Education Act 1996; and 'school building' means any building forming a school or part of a school.

Approved Document E for the England Building Regulations states in paragraph 0.12 (and also paragraph 8.1) that:

0.12 In the Secretary of State’s view the normal way of satisfying Requirement E4 will be to meet the values for sound insulation, reverberation time and indoor ambient noise which are given in Section 1 of the Building Bulletin 93 ‘The Acoustic Design of Schools, performance standards’, published by the Department for Education and made available on the internet at www.gov.uk.

Approved Document E will apply to building work carried out on excepted energy buildings in Wales as defined in the Welsh Ministers (Transfer of Functions) (No. 2) Order 2009. Apart from this exception, for the time being, Wales will continue to use the original Approved Document E 2010 edition).

It should be noted that the main changes to the 2015 amendment to Approved Document E were an update of the references to standards for schools.

Building regulations for Scotland

Section 5 of the Scottish Building Standards Agency (SBSA) Technical Handbook for Non-Domestic buildings contains acoustic requirements. However, due to limits of application given in the SBSA document, none of the acoustic performance requirements are applicable to schools.

Building regulations for N. Ireland

The Building Regulations for Northern Ireland do not provide requirements for acoustic performance of school buildings. The only acoustics requirements given are related to dwellings.

Technical Booklet G: Resistance to the passage of sound contains acoustic guidance for buildings which refers to Building Bulletin 93 for guidance relating to schools.

Building Bulletin 93 ‘The Acoustic Design of Schools’

Building Bulletin 93 'The Acoustic Design of Schools' also known as BB93, is published by the Department for Education (DfE) and is a direct replacement for Part A of Building Bulletin 87 ‘Guidelines for environmental design in schools’.

Section 1 of BB93 is intended for designers and Building Control Bodies. It gives the performance targets for compliance with Requirement E4 from Part E of The Building Regulations.

The standard ensures schools comply with the acoustic requirements of the following regulations:

• The Building Regulations
• The School Premises Regulations 2012
• The Independent Schools Standards 2013

Airborne sound

BB93 assigns an activity noise rating and a noise tolerance rating to different room types. Ratings for some of the most common room types are tabulated below.

Activity noise and noise tolerance ratings (Extract from Table 1.1 from BB93)

Room type	Classification		Maximum indoor ambient noise level, LAeq 30min (dB)
	Activity noise (Source room)	Noise tolerance (Receiving room)
Nursery school playroom	High	Low	35
Primary school classroom	Average	Low	35
Secondary school classroom	Average	Low	35
Music classroom	Very high	Low	35
Assembly Hall	High	Low	35
Dining room	High	High	45

Note:

• BB93 includes many more room types than listed here

These noise ratings are then used to determine the required sound insulation performance between adjacent spaces (see following table). A maximum indoor ambient noise level is also stated.

Sound insulation requirements between spaces (Table 1.2 from BB93)

Noise tolerance in receiving room	Minimum DnT(Tmf,max),w (dB)
	Activity noise in source room
	Low	Average	High	Very high
High	30	35	45	55
Medium	35	40	50	55
Low	40	45	55	55
Very low	45	50	55	60

BB93 provides specific values for airborne sound insulation between corridors, stairwells or other circulation spaces; these are shown in the next table.

Sound insulation requirements between corridors, stairwells or other circulation spaces
(Table 1.3 from BB93)

Types of space	Minimum Rw (dB)		Minimum Dn,e,w-10lgN (dB)
	Wall incl. glazing	Doorset (alone)
All spaces (excl. music rooms)	40	30	39
Music rooms	45	35	45

Impact sound

BB93 specifies the acoustic performance of floors for impact sound for different types of room (see following table). Impact sound insulation should be designed and measured for floors without a soft covering, e.g. carpet, foam backed vinyl, except in the case of concrete structural floor bases where the soft covering is an integral part of the floor.

Impact sound requirements for floors (Extract from Table 1.4 from BB93)

Room type (receiving room)	Maximum weighted standardised impact sound pressure level L’nT(Tmf,max),w (dB)
Nursery school playroom	65
Primary school classroom	60
Secondary school classroom	60
Music classroom	55
Assembly Hall	60
Dining room	65

Note:

• BB93 includes many more room types than listed here

Rain noise on roofs should be considered under Section 3.1.1 of BB93. However, no specific sound level limits are set.

Reverberation of sound

A requirement of BB93 is that schools buildings provide suitable reverberation times for clear communication of speech between teacher and student and between students, and for music teaching and performance. The following table gives some of the required mid-frequency reverberation times for room types.

Required mid frequency reverberation times (Extract from Table 1.5 from BB93)

Room type (receiving room)	Mid-frequency reverberation times Tmf (seconds)
Nursery school playroom	< 0.6
Primary school classroom	< 0.6
Secondary school classroom	< 0.8
Music classroom	< 1.0
Assembly Hall	0.8 to 1.2
Dining room	< 1.0

Note:

• BB93 includes many more room types than listed here

Speech transmission index

Open-plan spaces require extra specification in order to provide clear communication of speech between teacher and student, and between students, as they are complex acoustic spaces. Therefore, a minimum Speech Transmission Index (STI) is specified in BB93 where it is recommended that a computer model is used to predict the STI.

For open-plan teaching and study spaces the STI must be > 0.6.

Demonstrating compliance

Acoustic testing is recommended in BB93 to demonstrate compliance with the performance requirements. BB93 recommends that the requirement for testing is included, by the client, in the building contract.

Music Rooms

For the design of music rooms in schools the Department for Education published a dedicated design guide in 2010 entitled Music accommodation in secondary schools: A design guide as a revision to the 1997 Building Bulletin 86 entitled ‘Music Accommodation in Secondary Schools: A Design Guide’. However, for the majority of acoustic requirements the document refers back to BB93.

Hospitals

Building regulations for England & Wales

In both England and Wales, the Building Regulations do not include requirements for the acoustic performance of hospital buildings.

In Approved Document E the definition of ‘room for residential purposes’ specifically excludes rooms in hospitals and other similar establishments used for patient accommodation.

Building regulations for Scotland

Section 5 of the Scottish Building Standards Agency (SBSA) Technical Handbook for Non-Domestic buildings contains acoustic requirements. However, due to limits of application given in the SBSA document, none of the acoustic performance requirements are applicable to hospitals. Readers are referred to SHTM 2045 for guidance on designing for noise in hospitals and healthcare facilities.

Building regulations for Northern Ireland

The Building Regulations for Northern Ireland do not provide requirements for acoustic performance of hospital buildings. The only acoustics requirements given are related to dwellings.

HTM 08-01: Acoustics

The Department for Health has set out the performance criteria for hospitals in HTM08-01.

HTM 08-01 sets out the recommended acoustic criteria for the design and management of new healthcare facilities, covering important issues such as:

• Noise levels in rooms – including contributions from both mechanical services within the building and external sources transmitted via the building structure
• External noise levels – noise created by the healthcare building and operation should not affect those that live and work around it
• Airborne and impact sound insulation between rooms
• Control of reverberation in rooms
• Audio systems for public announcements.

Noise, which can be defined as ‘unwanted sound’, can increase heart rate, blood pressure, respiration rate and even blood cholesterol levels. Good acoustic conditions essentially help to provide a comfortable environment for staff and patients, resulting in raised staff moral, improved patient privacy and promoting essential sleeping patterns – which are key elements to healing.

Noise Levels in Rooms

There are two separate criteria; external noise intrusion and mechanical services noise. The criteria for the former are internal equivalent continuous sound pressure level, L_Aeq, targets over typical 1-hour daytime periods (and also night-time for wards). Targets for maximum noise levels, L_Amax, are also set for wards and operating theatres. Criteria for noise intrusion from external sources are tabulated below.

Criteria for noise intrusion from external sources

Room type	Example	Criteria for noise intrusion to be met inside the spaces from external sources (dB)
Ward – single person	Single-bed ward, single-bed recovery areas and on-call room, relatives overnight stay	40 LAeq, 1hr daytime 35 LAeq, 1hr night 45 LAmax, f night
Ward - multi-bed	Multi-bed wards, recovery areas	45 LAeq, 1hr daytime 35 LAeq, 1hr night 45 LAmax, f night
Small office-type spaces	Private offices, small treatment rooms, interview rooms, consulting rooms	40 LAeq, 1hr
Open clinical areas	A&E	45 LAeq, 1hr
Circulation spaces	Corridors, hospital street, atria	55 LAeq, 1hr
Public areas	Dining areas, waiting areas, playrooms	50 LAeq, 1hr
Personal hygiene (en-suite)	Toilets, showers	45 LAeq, 1hr
Personal hygiene (public and staff)	Toilets, showers	55 LAeq, 1hr
Small food preparation areas	Ward kitchens	50 LAeq, 1hr
Large food preparation areas	Main kitchens	55 LAeq, 1hr
Large meeting rooms (> 35 m2 floor area)	Lecture theatres, meeting rooms, board rooms, seminar rooms, classrooms	35 LAeq, 1hr
Small meeting rooms (< 35 m2 floor area)	Meeting rooms, seminar rooms, classrooms, board rooms	40 LAeq, 1hr
Operating theatres	Operating theatres	40 LAeq, 1hr 50 LAmax, f
Laboratories	Laboratories	45 LAeq, 1hr

For mechanical services, Noise Rating (NR) levels are recommended, although these exclude noise from specialist medical equipment. NR is a method of producing a single value for a noise that is made up of several frequencies and the sound in decibels is different at different frequencies. NR 40 will be a louder noise than NR 30 for example. Criteria for internal noise from mechanical and electrical services are tabulated in the next table.

Criteria for internal noise from mechanical and electrical services

Area type	Example	Noise from mechanical and electrical services
Ward areas, sleeping areas	Single-bed ward, multi-bed ward, on-call rooms, relatives overnight stay	NR 30
	Recovery rooms	NR 35
Small office-type spaces	Private offices, treatment rooms, interview rooms, consulting rooms	NR 35
Open clinical areas	A&E	NR 40
Circulation spaces	Corridors, hospital street, atria	NR 40
Public areas	Waiting areas, dining, playroom	NR 40
Personal hygiene (en-suite)	Toilets, showers	NR 40
Personal hygiene (general access)	Toilets, showers	NR 45
Small food preparation areas	Ward kitchens	NR 40
Large food preparation areas	Main kitchens	NR 50 (NR 55 below extract hoods)
Large meeting rooms (>35 m2 floor area)	Lecture theatres, meeting rooms, seminar rooms, board rooms, classrooms	NR 30
Small meeting rooms (<35 m2 floor area)	Meeting rooms, seminar rooms, board rooms, classrooms	NR 35
Operating theatres (excluding laminar-flow theatres)	Operating theatres	NR 40
Laminar-flow theatres	Ultra-clean theatre	NR 50
Laboratories	Laboratory without fume cupboards	NR 40
	At 1 m from fume cupboards with open sash	NR 60
Utility rooms	Clean utility, dirty utility	NR 40

Noise from sirens and helicopters can be common around hospitals, although designing the building fabric to combat this would be impractical. Site planning is therefore important.

Targets for controlling rain noise are set, which has implications for the design of light-weight roof systems. Indoor ambient-noise levels during ‘heavy’ rainfall should not exceed the intrusive noise criteria in stated in the above table by more than 20 dB(A) or should not be more than 65 dB(A), whichever is lower. Note: ‘Heavy’ rainfall is as defined in BS EN ISO 140-18.

Sound insulation

Noisy activities should not interfere with the requirements of adjacent rooms, and private conversations should not be overheard outside the room.

To achieve this, airborne and impact sound insulation criteria are set which are to be achieved on-site. Acoustic design is required to identify suitable partition types and devise appropriate flanking details. Sound insulation values to be achieved on site and sound insulation parameters for rooms are tabulated in the next tables.

For long term patient accommodation, Approved Document E should apply.

Sound insulation, D_nT,w (dB) to be achieved on site

Privacy requirement for source room	Noise generation of the source room	Noise sensitivity of receiving room
		Not sensitive	Medium sensitivity	Sensitive
Confidential	Very high	47	52
	High	47	47	52
	Typical	47	47	47
	Low	42	42	47
Private	Very high	47	52
	High	42	47	52
	Typical	42	42	47
	Low	37	42	42
Moderate	Very high	47	52
	High	37	42	47
	Typical	37	37	42
	Low	No rating	No rating	37
Not private	Very high	47	52
	High	No rating	42	47
	Typical	No rating	No rating	42
	Low	No rating	No rating	37

Definitions of privacy categories are:

• Confidential – raised speech would be audible but not intelligible, and normal speech would be inaudible.
• Private – normal speech would be audible but not intelligible.
• Moderate – normal speech would be audible and intelligible but not intrusive.
• Not private – normal speech would be clearly audible and intelligible.
• Sensitive – room cannot accommodate any noticeable noise from rooms next door.
• Medium sensitivity – room generally needs to be free from noise of other rooms.
• Not sensitive – noise from other rooms does not affect the use of the receiving room.
• If a receiving room does not have the minimum amount of acoustically absorbent material (see 'Room Acoustics' below), +3 dB should be added to the values of the table above.

Sound insulation parameters of rooms

Room – Clinical areas	Privacy requirement for source room	Noise generation of source room	Noise sensitivity of receiving room
Single-bed / on-call room	Confidential	Typical	Medium
Multi-bed room	Moderate	Typical	Medium
Children & older people (single bed)	Private	High	Medium
Children & older people (multi-bed)	Moderate	High	Medium
Consulting room	Confidential	Typical	Medium
Counselling / bereavement room	Confidential	High	Medium
Interview room	Confidential	Typical	Medium
Operating theatre suite	Private	Typical	Sensitive
Nurseries	Moderate	Very high	Medium
Birthing room	Private	Very high	Medium
Laboratories	Moderate	Typical	Medium
Dirty utility/sluice	Not Private	High	Not sensitive
Clean utility	Not Private	Low	Not sensitive
Speech and language therapy	Confidential	High	Sensitive

Note:

• HTM 08-01 gives more room types than given here and includes public areas and staff

For impact sound, a weighted standardised impact sound pressure level (L'_nT,w) of 65 dB is considered a reasonable maximum value for floors over noise-sensitive areas. Individual situations that may require extra impact sound insulation should also be considered (for example floors over multi-sensory/Snoezelen rooms).

Room Acoustics

Guidance is provided on the appropriate quantity of acoustically absorbent material, as opposed to set targets for reverberation time. In most spaces, it is advised that a Class C absorber (at least) is applied to an equivalent of 80% of the floor area.

Demonstrating compliance

Section 7 of HTM 08-01 covers ‘Testing and validation’ and includes guidance on all aspects of testing to demonstrate compliance with HTM 08-01. Crucially, HTM 08-01 states that a testing programme should be agreed before construction and that it should include testing of; sound insulation, noise levels generated by mechanical and electrical services, intrusive noise and environmental noise.

In the event of a failure to meet the project’s acoustic criteria, elements that do not meet the agreed performances set out in the acoustic strategy document should be remedied.

Commercial buildings

Commercial buildings include those used for; offices, retail, industrial activities and leisure activities. Therefore, the following building types are discussed:

• Retail
• Offices
• Industrial
• Cinemas
• Mixed-use

Building Regulations

The Building Regulations for England, Wales, Scotland, and Northern Ireland do not include requirements for acoustic performance of commercial buildings.

BS 8233 – Sound insulation and noise reduction for buildings

Sound insulation requirements for commercial buildings are covered in BS 8233: 2014, which deals with the control of noise from outside the building, noise from plant and services within it, and room acoustics for non-critical situations, i.e. it is not applicable to auditoria for example. BS 8233 is a code of practice that is intended for use by non-specialist designers and constructors of buildings and those concerned with building control, planning and environmental health. The code 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.

Retail buildings

Retail spaces vary enormously in their nature e.g. from small individual shops to large department stores to open plan shopping centres to industrial warehouse style retail premises. The type of retail space will affect the desired and acceptable acoustic properties and the solutions used to achieve those properties.

Sound Insulation

It is important to consider passage of sound between adjacent buildings or from street-to-store. Appropriate sound insulation levels for separating walls and floors may be determined by comparison with levels specified in Approved Document E, BB93 or HTM 08-01.

Reverberation

In shopping malls with tall ceilings echo is potentially a problem. Reverberation can be controlled with the specification of suitable wall, floor and ceiling finishes.

Ambience

Correct specification of materials can significantly affect the acoustic performance of the space and the ambience that is created. This is particularly the case in large open spaces such as car show-rooms, in areas with large hard surfaces and in stores where the quality of music and/or PA system is important.

BS 8233 recommends an indoor ambient noise level for a (unoccupied) department store of 50 dB L_Aeq,T.

Offices

The main source of guidance for required acoustic performance of office buildings is the British Council for Offices (BCO) Guide to Specification. The main considerations are; external noise intrusion, internal noise and noise from building services.

External noise intrusion

External noise intrusion levels should, after attenuation by the composite building envelope, not exceed the following acoustic design criteria:

• Open plan offices = NR 40 (L_eq)
• Speculative offices = NR 38 (L_eq)
• Cellular offices = NR 35 (L_eq).

In naturally ventilated buildings it may be appropriate or necessary to accept higher levels than those given above (e.g. +5 dB). The required level of sound insulation provided by the composite building envelope will depend on the location of the office building and its proximity to external noise sources.

Measures to minimise the impact of rainfall noise should be considered.

Sound insulation

Confidentiality between meeting rooms and offices is obviously a significant design consideration. There are no specific regulations for attenuation levels for separating walls and floors between different offices. It is important to ensure appropriate building envelope to limit the passage of sound from street to office.

The BCO Guide suggests the following performance values:

• Floors, D_nT,w > 45 to 48 dB
• Separating walls, D_nT,w > 45 to 48 dB
• Partitions, D_nF,w > 45 dB (laboratory flanking performance).

Alternatively, appropriate sound insulation levels for separating walls and floors may be determined by comparison with levels specified in Approved Document E, BB93 or HTM 08-01.

Privacy between offices and between an office and an occupied space requires good sound insulation and moderate background noise to mask intruding speech. The guidance given in BS 8233 is that:

• The minimum acceptable sound insulation between two cellular offices should be D_w = 38 dB
• Where conversation privacy is important the minimum sound insulation should be D_w = 48 dB.

Although even at D_w = 48 dB, it is possible that voices will be heard, but the conversation will not usually be understood.

Where the indoor ambient noise level is low it may be necessary to design for higher insulation values. As a rough guide, speech will be audible but not intelligible if:

D_w + L_A > 75 dB

Where;

• D_w is the weighted level difference between rooms
• L_A is the indoor ambient noise level in the room.

If demountable partitions are used to form cellular offices, it is unlikely that the sound insulation will be sufficient to achieve good quality privacy.

Reverberation

The problem of reverberation and echo are more likely to occur in atria and in rooms with high ceilings. In meeting rooms and presentation rooms speech intelligibility is very important and the reverberation of sound must be controlled.

Industrial buildings

For industrial buildings it is the noise levels within a building that are much more important than the transmission of noise around the building. However, industrial buildings often have the joint problem of protecting the workforce and neighbours from noise.

The Control of Noise at Work Regulations is the main piece of legislation for industrial buildings. Other regulations that include noise requirements for industrial buildings are the Health and Safety at Work Act, and the Control of Pollution Act, .

MCRMA technical paper No 8 provides a guide to acoustic design for metal roofing and cladding constructions.

Cinemas

There are no specific guidelines for cinemas but it is reported that certain leading architects and cinema operators work to a figure of R_w ≥ 74 dB airborne sound insulation between auditoria.

Mixed-use buildings

Modern buildings often contain a mixture of uses (usually on different storeys) such as residential, offices, retail and car parking. The sound insulation between the different uses is an important design consideration which would normally affect the floor designs.

The Becketts, Leeds - Mixed use development of residential, retail and car parking

There are no specific regulatory limits for mixed-use buildings in terms of acoustic insulation. However, the regulations and guidance relating to the individual uses of the building should be applied. Where walls or floors separate different uses the most onerous acoustic requirement relating to either use should be applied.

Summary

A summary of typical acoustic requirements for buildings in different sectors is presented in the table below. For cases where the exact requirement depends on the use of adjacent rooms, e.g. schools, hospitals, etc. the requirement presented is for a typical more onerous situation but not necessarily the most onerous case that could be envisaged because these would normally be avoided by careful planning of the internal layout of the buildings.

Summary of sound insulation requirements

Sector	Walls	Floors
	Airborne sound	Airborne sound	Impact sound
Residential	DnTw + Ctr ≥ 45 dB	DnTw + Ctr > 45 dB	L’ntw ≤ 62 dB
Schools	DnTw ≥ 55 dB	DnTw ≥ 55 dB	L’ntw ≤ 60 dB
Hospitals	DnTw ≥ 52 dB	DnTw ≥ 52 dB	L’ntw ≤ 65 dB
Offices	DnTw ≥ 45 dB	DnTw ≥ 45 dB
Cinemas	Rw ≥ 74 dB

Conversion of units

As can be seen from the table above, different sectors use different units of measurement to express the airborne acoustic requirements. Direct conversion of units is not possible due to the way the properties are determined. However, the following gives an approximate method of conversion to aid comparison of the requirements.

• D_ntw is a measurement of the airborne sound insulation between two rooms achieved by on site testing and therefore includes flanking sound leakage around the separating wall (or floor).
• C_tr is a sound spectrum adaptation factor to take account of low frequency sound and is typically -6 to -16 dB for light weight (wall) construction. For concrete floors values are typically -5 to -9 dB.
• R_w is a measurement of the airborne sound insulation between two rooms achieved by laboratory testing and therefore does not include flanking sound leakage around the separating wall (or floor).

The amount of flanking sound leakage around a separating wall depends on many factors e.g. wall construction, floor construction, junction details, quality of workmanship and room geometry. A typical value of flanking sound would be in the range of 4 to 6 dB.

Building Bulletin 93 gives the following approximate relationship between R_w and D_nT,w.

R_w = (approx) D_nT,w + 10 x Log (S x T / V) + 8 dB + F

where:

• S = surface area of the separating wall in m²
• T = maximum reverberation time for the room in seconds
• F = value to allow for flanking sound in dB
• V = volume of the receiving room in m³.

Based on the typical values given above and general room geometries, the approximations given below may be used:

• R_w = D_nT,w + 5 dB
• D_nT,w = D_nT,w + C_tr + 12 dB (for walls)
• D_nT,w = D_nT,w + C_tr + 7 dB (for floors)

Using the approximations presented above, a new table has been produced which, to aid direct comparison, expresses all the airborne sound insulation requirements in terms of R_w. The data are tabulated below.

Converted summary of sound insulation requirements

Sector	Walls	Floors
	Airborne sound	Airborne sound	Impact sound
Residential	Rw ≥ 62 dB	Rw ≥ 57 dB	L’ntw ≤ 62 dB
Schools	Rw ≥ 60 dB	Rw ≥ 60 dB	L’ntw ≤ 60 dB
Hospitals	Rw ≥ 57 dB	Rw ≥ 57 dB	L’ntw ≤ 65 dB
Offices	Rw ≥ 50 dB	Rw ≥ 50 dB
Cinemas	Rw ≥ 74 dB

Further reading

• Carl Hopkins. Sound insulation. Elsevier, Butterworth-Heinemann, 2007
• M.W. Simons & J. R. Waters. Sound Control in Buildings. A guide to Part E of the Building Regulations. Blackwell publishing, 2004
• BS EN ISO 10140: 2021 Acoustics. Laboratory measurement of sound insulation of building elements. Various parts. British Standards Institution.
• Robust Details

Resources

• SCI P372 Acoustic Detailing for Steel Construction
• SCI P371 Acoustic performance – Case Studies

See also

• Acoustics
• Introduction to acoustics
• Acoustic performance of walls
• Acoustic performance of floors
• Junction details for acoustic performance
• Integration of elements for acoustic performance
• Multi-storey office buildings
• Single storey industrial buildings
• Retail buildings
• Healthcare buildings
• Education buildings
• Leisure buildings
• Residential and mixed-use buildings

CPD

• Acoustics and steel construction