INTRODUCTION

The New Approved Document E, (2003 Edition) was implemented on 1st July 2003. It's primary objective is to raise the standard of sound insulation in all dwellings to counter the rising level of complaints received about noise transmission. Noise nuisance has a detrimental effect on a homeowner or resident's quality of life so the aim is to improve the sound insulation both between and within dwellings, as well as between rooms in hostels, hotels and residential homes. The scope has been extended to cover reverberation in common parts of blocks of flats and acoustic conditions in schools.

Who are affected by these changes?
• Buildings where there has been a change of use relating to conversions and refurbishments - Effective from 1st July 2003.
• New build houses and flats - Effective from 1st January 2004.
• Domestic Extensions.

Approved Document E is split into four sections:
E1 – Protection against sound from other parts of the building and adjoining buildings.
E2 – Protection against sound within a dwelling/house etc
E3 – Reverberation in the common internal parts of buildings containing flats or rooms for residential purposes
E4 – Acoustic Conditions in Schools

In respect of E1 and E2 the document gives examples of constructions which if built correctly should achieve the sound insulation values set out in Table 1a and Table 1b below.

To satisfy Requirement E3, sound absorption measures described in Section 7 of the Approved Document will need to be followed.
To satisfy the Requirement E4, reference is made to, Building Bulletin 93 ‘The Acoustic Design of Schools’ published by the DfES during 2003.

Pre-Completion Testing
• For the first time, buildings are to be tested prior to completion in order to confirm they meet or exceed Part E standards.
• The Regulations require that one in ten of each construction type requires testing.
• All tests are at the Building Inspectors discretion.
• Failure in the test, will result in the sound insulation needing to be improved and the construction type re-tested.

Full details of pre-completion testing are explained in Section 1 of the Approved Document.

Reverberation in the common parts of buildings containing flats or rooms for residential purposes.
A new requirement to control reverberation in the common parts of buildings containing flats and ‘rooms for residential purposes’. Pre-completion site testing is not required.

Robust Details.
These are a set of standards developed by the House Builders Federation. They will be permitted to demonstrate compliance with Part E of the Building Regulations, as an alternative to pre-completion testing. Amended regulations are to be published allowing Robust Details to come into force on July 1st 2004, applying only to sound insulation between new developments, houses and flats.

Acoustic conditions in schools
New schools are now controlled under the Building Regulations.This includes sound insulation, reverberation time and indoor ambient noise levels. The normal way of satisfying requirement E4 will be to meet the values for sound insulation, reverberation time and internal ambient noise which are given in section 1 of Building Bulletin 93 ‘The Acoustic Design of Schools’ produced by DfES. (IBSN: 0 11 271105 7).

The new performance requirements are considerably more onerous than those set out in the 1991 Edition.This is due to the addition of a low frequency correction factor (Ctr) which must be applied to the pre-completion measure of airborne sound. As a consequence, the new values will be more difficult to achieve for many types of construction. Note:

• Associated flanking constructions should be followed
• The person carrying out the building work should arrange for sound insulation testing to be carried out by a test body with appropriate third party accreditation

Tables 1a and 1b below illustrate the airborne sound insulation and impact sound insulation values required in the various types of dwellings. Please note that in the case of Airborne sound insulation, DnTw is the measurement used, however as low-frequency sound is the most difficult frequency range to stop a Ctr (correction factor) is used to take this into account. LnTw is measurement used to measure the impact sound insulation of floors (on site).

With Airborne Sound, the higher the DnTw + Ctr figure the better, and with Impact sound the lower the LnTw figure the better.

Importance of design and good workmanship
In all cases, good design and installation practice should be followed. It is imperative that measures to eliminate or minimise flanking sound transmission are considered at the design stage and that products are installed correctly by the builder. Failure to do so may lead to limitation of acoustic performance and the requirements of the Building Regulations not being met.

Flanking noise
when attempting to make any sort of construction compliant to the Part E Regulations it is important to note that sound does not always go straight through the building element. Indeed if the wall/floor/partition concerned has good sound reducing capabilities then the sound will simply find the easiest way to get from A to B. In short, it it can’t go through the wall, it will go up and over or around the side. This is called Flanking Transmission and occurs when sound travels along elements shared by adjacent structures. If flanking constructions are not correctly specified or constructed, flanking transmission can exceed direct transmission and damage the overall capabilities of the construction.One way of dealing with this issue is to use isolation strips around the perimeter edges of floors and walls, as well as the use of an acoustic sealant wherever possible. The New Approved Document E provides advice with respect to flanking details.

Part H (Scotland)
The Building Regulations Part H (6th Amendment to the Technical Standards) has been in force since 4th March 2002.The key variations between Part E and Part H are summarised in the following table and notes.

Airborne Sound.
Minimum values of weighted standardised level difference (DnT,W) as defined in BS EN ISO 717-1:1997

Conclusion.
Compliance (apart from Schools and Reverberation) is by one of three routes.
• For new houses and flats only, from July 1st 2004, use Robust Details in accordance with the rules and procedures of Robust
Details Ltd. (www.robustdetails.com).
• Build using construction details contained in the guidance sections of the approved document, then sound test to achieve the specified performance requirements.
• Build using alternative designs, materials or products supported by advice from an appropriate source. Then sound test to achieve the specified performance requirements.

For those independent developers and homeowners who now find that their potential changes mean they must comply with the new regulations, the last method, which will involve subcontracting the problem to a specialst firm, will prove to be the simplest. This is where companies, such as ourselves, with many years expertise in this specialist field are in an ideal position to help with your requirements.

Explanation of terms
In an attempt to decipher some of the terms and abbreviations you may come across relating to acoustics and Part E Building regulations the following may prove useful.
NOTE: A more in-depth GLOSSARY on general noise control and acoustics is provided from the GLOSSARY button in the INFORMATION section accessed from the links in this paragraph or the main navigation bar at the top of the page.

Absorption : Conversion of sound energy to heat, often by the use of a porous material.

Absorption coefficient : A quantity characterizing the effectiveness of a sound absorbing surface. The proportion of sound energy absorbed is given as a number between zero (for a fully reflective surface) and one (for a fully absorptive surface). Note that sound absorption coefficients determined from laboratory measurements may have values slightly larger than one. See BS EN 20354:1993.

Absorptive material : Material that absorbs sound energy.

Airborne sound : Sound propagating through the air.

Airborne sound insulation : Sound insulation that reduces transmission of airborne sound between buildings or parts of buildings.

Air path : A direct or indirect air passage from one side of a structure to the other.

Caulking : Process of sealing joints.

Cavity stop : A proprietary product or material such as mineral wool used to close the gap in a cavity wall.

Ctr : The correction to a sound insulation quantity (such as DnT,w) to take account of a specific sound spectra. See BS EN ISO 717-:1997.

dB : (See decibel)

Decibel (dB) : The unit used for many acoustic quantities to indicate the level with respect to a reference level.

Density : Mass per unit volume, expressed in kilograms per cubic metre (kg/m3).

Direct transmission : The process in which sound that is incident on one side of a building element is radiated by the other side.

DnT : The difference in sound level between a pair of rooms, in a stated frequency band, corrected for the reverberation time. See BS EN ISO 140-4:1998.

DnT,w : A single-number quantity which characterizes the airborne sound insulation between rooms. See BS EN ISO 717-1:1997.

DnT,w + Ctr : A single-number quantity which characterizes the airborne sound insulation between rooms using noise spectrum no. 2 as defined in BS EN ISO 717-1:1997. See BS EN ISO 717-1:1997.

Dynamic Stiffness : A parameter used to describe the ability of a resilient material or wall tie to transmit vibration. Specimens with high dynamic stiffness (dynamically ‘stiff’) transmit more vibration than specimens with low dynamic stiffness (dynamically ‘soft’). See BS EN 29052-1:1992 for resilient materials. See BRE Information Paper IP 3/01 for wall ties.

Flanking Element : Any building element that contributes to sound transmission between rooms in a building that is not a separating floor or separating wall.

Flanking transmission : Sound transmitted between rooms via flanking elements instead of directly through separating elements or along any path other than the direct path.

Floating floor : A floating floor consists of a floating layer and resilient layer (see also resilient layer and floating layer).

Floating layer : A surface layer that rests on a resilient layer and is therefore isolated from the base floor and the surrounding walls (see also resilient layer).

Framed wall : A partition consisting of board or boards connected to both sides of a wood or metal frame.

Frequency : The number of pressure variations (or cycles) per second that gives a sound its distinctive tone. The unit of frequency is the Hertz (Hz).

Frequency band : A continuous range of frequencies between stated upper and lower limits, (see also octave band and one-third-octave band).

Hertz (Hz) : The unit of the frequency of a sound (formerly called cycles per second).

Impact sound : Sound resulting from direct impact on a building element.

Impact sound insulation : Sound insulation which reduces impact sound transmission from direct impacts such as footsteps on a building element.

Independent ceiling : A ceiling which is fixed independently of a separating floor or an internal floor (see separating floor and internal floor).

Internal floor : Any floor that is not a separating floor (see separating floor).

Intermediate landing : A landing between two floors (see also landing).

Internal wall : Any wall that does not have a separating function.

Isolation : The absence of rigid connections between two or more parts of a structure.

Landing : A platform or part of floor structure at the end of a flight of stairs or ramp.

L’nT : The impact sound pressure level in a stated frequency band, corrected for the reverberation time. See BS EN ISO 140-7:1998.

L’nT,w : A single-number quantity used to characterize the impact sound insulation of floors. See BS EN ISO 717-2:1997.

Mass per unit area : Mass per unit area is expressed in terms of kilograms per square metre (kg/m2).

Noise : Noise is unwanted sound.

Octave band : A frequency band in which the upper limit of the band is twice the frequency of the lower limit.

One-third-octave band : A frequency band in which the upper limit of the band is 21/3 times the frequency of the lower limit.

Rw : A single-number quantity which characterizes the airborne sound insulation of a material or building element in the laboratory. See BS EN ISO 717-1:1997.

Resilient layer : A layer that isolates a floating layer from a base floor and surrounding walls.

Reverberation : The persistence of sound in a space after a sound source has been stopped.

Reverberation time : The time, in seconds, taken for the sound to decay by 60 dB after a sound source has been stopped.

Separating floor : Floor that separates flats or rooms for residential purposes.

Separating wall : Wall that separates adjoining dwelling-houses, flats or rooms for residential purposes.

Sound pressure level : A quantity related to the physical intensity of a sound.

Sound reduction index (R) : A quantity, measured in a laboratory, which characterizes the sound insulating properties of a material or building element in a stated frequency band. See BS EN ISO 140-3:1995.

Spectrum : The composition of a particular sound in terms of separate frequency bands.

Structure-borne sound : Sound which is carried via the structure of a building.

UKAS : United Kingdom Accreditation Service.

ΔLw : The measured improvement of impact sound insulation resulting from the installation of a floor covering or floating floor on a test floor in a laboratory. See BS EN ISO 717-2:1997.