Critical to achieving satisfactory protection from noise is the
performance of separating floors and walls. These elements must be
correctly specified and constructed if they are to provide the
required level of sound insulation.
Overview
As part of an overall
strategy to improve quality of life, the Government has introduced
tough new legislation. Commonly referred to as Part E, its aim is
to improve the sound insulation of new homes and conversions.
Several research studies have highlighted that millions of people
in the UK have their lives and privacy disturbed by noise from
neighbours. The Government recognised that noise is an increasingly
intrusive feature of daily living. Noise features in more than
two-thirds of complaints to Environmental Health Officers and
domestic noise complaints trebled in the ten years to 1996.
Critical to achieving satisfactory protection from noise is the
performance of separating floors and walls. These elements must be
correctly specified and constructed if they are to provide the
required level of sound insulation.
A further requirement of Part E is a minimum level of sound
insulation for intermediate floors within a dwelling.
Advantages
Mineral wool products offer substantial advantages when used as
both sound absorbent and resilient layers in floors that are
required to provide sound insulation.
Mineral wool provides an alternative method of controlling airborne
sound transmission through a floor as opposed to simply increasing
the mass. The sound reduction performance of floors can be greatly
increased by installing a layer of mineral wool in floor voids to
absorb energy from airborne sound waves. A secondary benefit of
mineral wool is to provide thermal separation between floors so
that rooms can be zoned independently for heating.
When used as a resilient layer to isolate the floor surface from
the structural deck, appropriate mineral wool products will
substantially reduce the transmission of impact sound through a
structure.
Knauf Insulation Products
- Crown Acoustic Partition Roll is made from glass
mineral wool and formed into unfaced rolls which are lightweight,
flexible, resilient and non-combustible.
- Crown Acoustic Joist Roll is made from glass mineral
wool and formed into unfaced rolls which are lightweight, flexible,
resilient and non-combustible.
- Crown Acoustic Floor Roll is a resilient, medium
density glass mineral wool roll, faced on one side with a kraft
paper/polythene laminate. The facing has a 75mm overlap along one
edge to lap the edge of the adjoining roll.
- Rocksilk Flexible Slab is an unfaced semi-rigid
non-combustible rock mineral wool slab.
- Rocksilk Acoustic Floor Slab is a rigid,
non-combustible, compression resistant slab of rock mineral
wool
- Rocksilk Acoustic Floor Slab Plus is a dense, rigid,
non-combustible slab of rock mineral wool which is highly
compression resistant
- Floorfoam is a closed cell
extruded polyethylene foam available in roll form
Summary
Knauf Insulation provide products that can be used as resilient
layers for the control of impact sound transmission in separating
floors and absorbent layers for the control of airborne sound
transmission in both internal and separating floors. Included in
the range are products that match the specifications of components
of RD separating
floors and internal floors deemed to satisfy with the Building
Regulations.
These products can also be used as components in separating
floors that have the potential to achieve the standards required by
Building Regulations but must be tested to show compliance.
Detailed below are separating floors for both new build and
refurbishment as well as internal floors in both timber and
masonry.
Detailed Design Considerations
With emerging policies for urban regeneration likely to involve
increased housing density, the Government resolved to improve
standards of sound insulation and to improve compliance
significantly with the introduction of post-construction testing of
dwellings.
The Approved Document for part Part E of the Building
Regulations, was revised in 2003 and focused on fthe
following four items:
- E1 - Protection against sound from other parts of the building
and adjoining buildings
- E2 - Protection against sound within a dwelling-house
- E3 - Reverberation in the common internal parts of buildings
containing flats or rooms for residential purposes
- E4 - Acoustic conditions in schools
Compliance with the Part E1 for separating walls and floors
can be demonstrated in two ways:
- Construct the separating wall or floor and demonstrate by
sound testing that the performance requiremens of Part E1 are
met
- For new-build construction only, construct the separating wall
or floor using a Robust
Detail – no sound test is required, but a fee is payable
to Robust Details Ltd.
RDs
Monitoring of the
RDs
will be carried out by Robust Details Ltd, a ‘not for profit’
company specifically set up for this purpose. See
http://www.robustdetails.com/.
Robust Details Ltd will organise quality checking of existing
RDs and be responsible for
the future approval of proposed new
RDs.
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 an
RD.
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, three
methods of sound transmission need to be considered:
- airborne sound
- impact sound
- flanking sound
The air tightness of the construction is also important.
Performance Standards for Separating Floors and
Stairs with Separating Function and Internal
Floors
| |
Airbourne Sound Insulation |
Impact Sound
Insulation |
| |
DnT,w
+Ctr dB*
(min values)
|
Rw dB
(min values)
|
L'nT,w dB
(max values)
|
| Purpose built dwellings, flats and
‘Rooms for Residential
Purposes’ |
| Internal floors |
- |
40** |
- |
| Separating floors and stairs |
45 |
- |
62 |
| Dwelling homes and flats formed from
‘material change of use’ |
| Internal floors |
- |
40** |
- |
| Separating floors and stairs |
43 |
- |
64 |
* The weighted average sound reduction index modified by
the addition of a factor to take into account problematic low
frequency sound.
** This is allowed to be qualified by laboratory rather than field
testing.
Airborne Sound
Airborne sound sources produce noise by vibrating the air
immediately around the sound source. 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 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
Increasing the mass of a floor
will improve its sound insulation but the amount of extra weight
that can be safely supported is often limited. As a result,
other design approaches are usually employed ie, isolation,
absorbent materials and resilient layers.
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.
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.
The rationale for using Mineral Wool for noise
control
The sound absorption characteristics of mineral wool make it
ideal for use in modern buildings to comply with the Part E
Regulations. In addition, the thermal properties of mineral wool
provide a secondary benefit of minimising heat loss either between
attached dwellings or between storeys within a dwelling. A further
benefit is to minimise the overall mass of the floor, easing
construction processes.
|
Typical Specification Clauses
1a) Timber floor with I beams – robust detail type
E-FT-1
Crown Acoustic Joist Roll, 100mm thick, to be placed between
the timber I beams.
Crown Acoustic Partition Roll, 25mm thick, to be unrolled between
the resilient floor battens. The Crown Acoustic Partition Roll
should be placed under any services running in the void between the
battens.
The ceiling and floor to be as specified by the designer.
Alternatively, refer to NBS clause: P10/240
1b) Timber separating floor
Crown Acoustic Joist Roll, 100mm thick, to be placed between
the independent ceiling joists.
Rocksilk Acoustic Floor Slab, 25mm thick, to be placed over the
floor deck. All joints to be close butted and taped.
The ceiling and platform floor to be as specified by the
designer.
Alternatively, refer to NBS clause: P10/240 and K11/225
1c) New independent ceiling
Crown Acoustic Joist Roll, 100mm thick, to be placed between
the independent ceiling joists. The ceiling to be as specified by
the designer.
Alternatively, refer to NBS clause: P10/240
1c) Platform floor
Crown Acoustic Joist Roll, 100mm thick, to be placed between
the existing floor joists.
Rocksilk Acoustic Floor Slab, 25mm thick, to be placed over the
existing floor deck and turned up at the perimeter. All joints to
be close butted and taped.
The floating platform floor to be as specified by the
designer.
Alternatively, refer to NBS clause: P10/240 and K11/225
2a) Concrete separating floor – robust detail type
E-FC-1, E-FC-2 or E-FS-1 with FFT4 floating floor
treatment
Rocksilk Acoustic Floor Slab Plus, 30mm thick, to be placed
over the structural floor. All joints to be close butted.
The floating chipboard floor to be as specified by the
designer.
Alternatively, refer to NBS clause: K11/225
2b) Concrete separating floor
Rocksilk Acoustic Floor Slab Plus, 25mm thick, to be placed
over the structural floor. All joints to be close butted.
Overlay Rocksilk Acoustic Floor Slab Plus with Polyfoam Floorfoam
5, turned up at the perimeter to isolate the screed from the
surrounding structure.
Minimum 65mm cement:sand screed or minimum 40mm proprietary screed
laid over the resilient layers. The screed to be isolated from wall
and structural elements in the floor.
Alternatively, refer to NBS clause: M10/125.
2b) Floating screed on concrete separating floor –
Type 2 in Approved Document E
Crown Acoustic Floor Roll, 25mm thick, to be laid with paper
face up, on the concrete floor and turned up vertically around the
floor perimeter.
Minimum 65mm cement:sand screed laid over the insulation. The
screed to be reinforced with a 20-50mm wire mesh. The screed to be
isolated from wall and structural elements in the floor.
Alternatively, refer to NBS clause: M10/125
2c) Floating timber deck on concrete separating
floor – Type 2 in Approved Document E
Crown Acoustic Floor Roll, 25mm thick, to be laid with paper
face down, on the concrete floor and turned up vertically around
the floor perimeter.
Minimum 18mm thick t&g timber boards or flooring grade
chipboard fixed to battens, minimum 45mm deep over and isolated
from wall and structural elements in the floor. Nails used to fix
the boards to the battens must not project below the battens.
Alternatively, refer to NBS clause: K11/115/125/135
3a) Internal floor – Type C in Approved Document
E
Crown Acoustic Joist Roll, 100mm thick, to be placed between
the floor joists. The ceiling and floor deck to be as specified by
the designer.
Alternatively, refer to NBS clause: P10/240
3b) Internal floor – Type B in Approved Document
E
Crown Acoustic Partition Roll, 25mm thick, to be supported by
the horizontal members of the Knauf C-Form II ceiling system.
The plasterboard ceiling to be as specified by the designer.