Part E
Resistance to the passage of sound (England and Wales)
2003
Key requirements
Part E Regulations focus on four main items:
- 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
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July 2002 ‘the initial Government proposal’
Details of the new Part E rules for building construction were
released in July 2002 and included requirements for:
Measures to improve sound insulation between adjoining dwellings
by use of higher performance standards which also take better
account of the transmission of low frequency sound. This included
"rooms for residential purposes" eg hotels and hostels, whether
purpose-built or formed by conversion of other buildings.
Post-construction testing of sound insulation between new
dwellings at a 10% sampling rate by type. (Also applies to
dwellings formed by change of use of a building).
Protection against sound within a dwelling based on current good
practice (not testing) ie requirements for partition walls.
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January 2003 ‘the building industry response’
Accepting the rationale for the changes, the construction
industry agreed that the new Part E1 regulations could partially
become effective on 1 July 2003 for new hostel and hotel types of
accommodation and houses, flats, hostel and hotel accommodation
formed by conversion of other building types.
However, for new houses and flats the implementation of new
requirements was deferred to 1st July 2004 based on representations
from the House Builders Federation (HBF) arguing that the scheme
would lead to delays and higher costs. Ministers asked for an
alternative solution and the HBF and building material suppliers
proposed new ‘high performance designs’, now referred to as Robust
Details (RDs). As sound insulation is dependent on the quality of
workmanship, it was proposed that RDs should be generally
over-engineered.
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How to comply
There are two routes to compliance
1. Robust Details
- Pre-approved details achieving sound insulation standards
higher than those required by Part E.
- For new build houses and new build apartments only.
- No pre-completion testing required.
Robust Details are an alternative to constructions that require
pre-completion sound testing in England and Wales.
The main benefit of using Robust Details is there is no need to
carry out pre-completion sound testing. This eliminates the risk
and uncertainty of remedial action being required on completed
separating walls and floors, which may lead to potential delays in
completing the property.
The Robust Details are designed to achieve higher sound
insulation standards than the minimum requirements in Part E. Each
approved Robust Detail contains a checklist which must be completed
on site. This is a quality control check to confirm that all the
critical factors that affect sound performance have been built
correctly.
Robust Details are administered by Robust Details Ltd. Every
dwelling built using Robust Details needs to be registered with
Robust Details Ltd and a plot registration fee paid. Further
information on the Robust Details scheme is available on the Robust
Details website at:
www.robustdetails.com
All floating floor and ceiling treatments for separating floors,
where stipulated, are to have a proven level of performance from
laboratory tests before they can be used in a Robust Detail.
2. Pre-completion testing
- Details designed to meet or exceed Part E minima.
- For all new build, refurbishment, remedial and extension work
in buildings with rooms for residential purposes.
- Minimum of 1 in 10 dwellings of same type to be tested.
Part E calls for sample pre-completion testing of separating
walls and floors prior to handover. The testing is required to
ensure that the level of performance specified in Part E is being
achieved.
Tests are to be performed to the ISO 140 series of standards.
Pre-completion sound insulation tests should be carried out by
independently accredited organisations.
A minimum of one in every 10 dwellings of the same dwelling type
are required to be tested prior to completion. Depending on the mix
of dwelling types in a development, testing will usually be
required on 10-30% of the units.
Tests should be conducted in completed but unfurnished rooms or
available spaces in the case of properties sold before fitting
out.
Table 11: Performance standards for separating walls, floors
and stairs with separating function
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airborne sound insulation |
Impact sound
insulation |
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Dn T,w + Ctr dB*
(min. values)
|
Rw dB
(min. values)
|
L’n Tw dB
(max. values)
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| Purpose built
dwellings, flats and rooms for residential purposes |
| Internal walls and floors |
- |
40‡ |
- |
| Separating walls |
45† |
- |
- |
| Separating floors and stairs |
45 |
- |
62 |
| Dwellings, homes
and flats formed from material change of use |
| Internal walls and floors |
- |
40‡ |
- |
| Separating walls |
43 |
- |
- |
| Separating floors and stairs |
43 |
- |
64 |
* Weighted average sound reduction index modified by the
addition of a factor to take into account problematic low frequency
sound
† 43 dB for separating walls in ‘Rooms for residential
purposes’
‡ This is allowed to be qualified by laboratory rather than
field testing
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New build semi-detached and terraced housing
1) Internal wall
Rw = min. 40db
2) Separating wall
Dn T,w + Ctr = min. 45db airborne
3) Internal floor
Rw = min. 40db
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New build flats and apartments
1) Separating wall
Dn T,w + Ctr = min. 45db airborne
2) Separating floor
Dn T,w + Ctr = min. 45db airborne
L’n Tw = max. 62dB impact
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What do the terms mean?
| dB
(decibel) |
- indicates the loudness of sound. |
| R |
- laboratory measure of airborne sound transmission. |
| Dn T,w +
Ctr |
- site measure of airbourne sound with low frequency correction
applied (higher figure = better performance). |
| Lnw |
- laboratory measure of the impact sound level (lower figure =
better performance). |
| L’n Tw |
- site measure of the impact sound level (lower figure = better
performance). |
The elements of noise control
When approaching a noise control problem, the difference between
sound absorption and sound insulation should be appreciated.
Sound Absorption
Sound Absorption refers to the attenuation of reverberant noise
within the same room or area as the noise source. This normally
involves lining all or part of the room surfaces with a material
which absorbs sound. In most houses and flats, the soft furnishings
provide a good degree of sound absorption. Adding additional sound
absorbent material is unlikely to lower the noise level in the room
significantly and will not produce a corresponding reduction in the
noise being transmitted to neighbouring premises.
Sound Insulation
Sound Insulation, otherwise known as sound reduction, is the
prevention of noise being transmitted from one part of a building
to another, for example by erecting a partition or wall.
Improving the sound insulation of walls and floors between
dwellings is the main way in which the noise transmission between
dwellings can be reduced.
When considering sound insulation in existing buildings,
three methods of sound transmission need to be
considered:
- airborne sound
- impact sound
- flanking sound
Airbourne Sound
Airborne sound sources produce noise by vibrating the air
immediately around them. Typical sources include the human voice,
musical instruments, home entertainment systems and noisy dogs.
The ability of an element of construction to resist the passage
of airborne sound energy through it is largely determined by three
factors:
- The sound absorbency of any cavities in the construction
- The structural isolation between the two outer surfaces
- Its mass
The airtightness of the construction is also important.
Increasing the mass of a wall or floor will improve its sound
insulation. However, the amount of extra weight that can be safely
supported by an existing construction is often limited so other
design approaches are usually employed in remedial work ie,
isolation, absorbent materials and resilient layers.
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Impact Sound
Impact noise sources produce noise by direct physical excitation
of part of a building.
Examples include slamming doors, stamping on the floor and
vibrating washing machines.
With impact noise, a relatively small noise source can result in
a loud sound being transmitted through the structure, often over
long distances.
Impact noise can be controlled by:
- providing a resilient layer at the point of impact - such as a
carpet
- structural isolation - such as adding a resilient layer between
the floor deck and the floor structure
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Flanking Sound
Flanking sound transmission usually refers to sound that travels
through ‘flanking’ structural elements, such as the external wall
that flanks a separating wall between two dwellings.
Flanking sound can also include sound that travels along
unintended airpaths, such as unsealed gaps in the structure and
around service penetrations.
Flanking transmission can be reduced by:
- extending the separating wall to the underside of the roof
- sealing open airpaths
- forming a lining backed by a resilient layer to prevent sound
energy entering the flanking element
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