rain noise …. solutions for metal roof constructions!
TRANSCRIPT
Rain Noise ….
Solutions for metal roof constructions!
Rain Noise?
To some a relaxing diversion!
However …
Impact noise from rain on
lightweight flat roof
constructions can significantly
increase indoor noise levels!
Rain NoiseBuilding Regulations
Approved Document E, 2004
Amendment requires construction
of new school buildings to follow
guidance provided by Building
Bulletin 93.
This includes a requirement to
minimise rain noise on
lightweight roofs.
Rain NoiseBuilding Regulations
BB 93 advises designers to consider
the effect of impact noise from rain
at an early stage of the roof design
in order to minimise disturbance
within the building.
Whilst no limit is set, methods of
control must be included and
justified to building control.
BB 93 Section 3, Part 3.1
This highlights the need for:
• Sound absorption
• Acoustic damping
• The use of additional mass and /
or an independent acoustic ceiling
• Laboratory measured data for
comparison of roof constructions
Rain Noise
Rain NoiseNew test standard
A new test standard for impact
sound from rain on the roof Draft
ISO 140-18 is under development.
The BRE were commissioned by
Rockwool Limited and Euro-Clad to
carry out sound intensity
measurements of rain noise on
specific roof constructions.
Rain Noise Testing
Two types of rain are defined by Draft ISO 140-18
• ‘Intense rain’ – return rate of one in 2 years
• ‘Heavy rain’ – return rate of one in 50 years
The intention is that “Heavy rain” will be the preferred type of
artificial rainfall for the comparison of products in Europe.
• ‘Moderate rain’ defined by BS 7527-2.2 –Typical UK rainfall
Used for testing
Rain Noise Testing
How are the measurements made?
A tank positioned above
the test roof is filled with
water and consistently
recharged
The flow rate is calibrated
to ensure correct rainfall
intensity
Rain Noise Testing
How are the measurements made?
All test constructions were assembled in accordance with manufacturers recommendations.
Rain Noise Testing
How are the measurements made?
Sound intensity
measurements were
taken below each roof
construction by the BRE
in the frequency range
of 50 Hz to 5000 Hz
Rain Noise Testing…some definitions
What is sound intensity?
• The sound power flowing
per unit area, in a given
direction, measured in W/m²
• Lower sound intensity levels represent improved acoustic
performance.
Rain Noise Testing…some definitions
Reverberant Sound Pressure level, LAeq
• Sound in an enclosed space which
results from repeated reflections at
the boundaries.
• Lower reverberant sound pressure
levels represent improved acoustic
performance.
Profiled metal roofing Rockwool Cladding Roll
Composite metal roof construction PIR insulation
Standing Seam Constructions With perforated liner, Cladding Roll, RW3 With non perforated liner, Cladding Roll, RW3
Combined with Rockwool Acoustic Membrane
Rain Noise TestingThe constructions tested
Profiled Cladding
• Euro-Clad liner 19mm, 0.4mm
•
Eurobar rail and bracket
spacer system
• Rockwool Cladding Roll 180mm
• Euro-Clad outer 32mm, 0.7mm
Test 1
Profiled metal roofing
• Profiled steel outer, 35 mm deep, 0.5mm thick
• PIR Insulation foam, 80mm thickness
• Profiled steel liner, 20mm deep, 0.4mm thick
Metal Roof
Test 2 PIRComposite metal
roofing
20
25
30
35
40
45
50
55
60
Frequency Hz
Sou
nd
in
ten
sity
dB
PIR Composite
Profiled Cladding
Rain Noise Testing BRE
Summary of the results
50 dB
76 dB 65 dB
Profiledmetal
cladding
Sound intensity level, LIA
Reverberant sound pressure levels, LAeq Classroom
Reverberant sound pressure levels, LAeq Gymnasium
PIR composite
panel
65 dB77 dB
62 dB
A – weighted acoustic measurements
Test 3 Perforated liner
Standing Seam
• Euro-Clad liner, 33mm, 0.7mm
• Top hat section
• Rockwool RW3 Slab, 30mm
• Vapour Control Layer
• Eurobar bracket & spacer system
• Rockwool Cladding Roll, 160mm
• Aluminium Halter
• Euroseam 400, 0.9mm
Test 4 Non perforated liner
Standing Seam
• Euro-Clad liner, 33mm, 0.7mm
• Top hat section
• Rockwool RW3 Slab, 30mm
• Eurobar bracket & spacer system
• Rockwool Cladding Roll, 160mm
• Aluminium Halter
• Euroseam 400, 0.9mm
20
25
30
35
40
45
50
55
60
Frequency Hz
Sou
nd
in
ten
sity
dB
Standing seam - perforated
Standing seam - non perforated
Rain Noise Testing BRE
Summary of the results
n/a
62 dB 58 dB
Sound intensity level, LIA
Reverberant sound pressure levels, LAeq Classroom
Reverberant sound pressure levels, LAeq Gymnasium
Standing Seam
58 dB62 dB
n/a
A – weighted acoustic measurements
Liner not perforated
Liner perforated
Not possible to measure at all frequency bands
Test 5 2 Layer Acoustic Membrane
Standing Seam
• Euro-Clad liner, 33mm, 0.7mm
• Tophat section
• Rockwool RW3 Slab, 30mm
• Rockwool Acoustic Membrane 5 (2 layers)
• Eurobar bracket & spacer system
• Rockwool Cladding Roll, 160mm
• Aluminium Halter
• Euroseam 400, 0.9mm
Test 6 3 Layer Acoustic Membrane
Standing Seam
• Euro-Clad liner, 33mm, 0.7mm
• Tophat section
• Rockwool RW3 Slab, 30mm
• Rockwool Acoustic Membrane 5 (2 layers)
• Eurobar bracket & spacer system
• Rockwool Cladding Roll, 160mm
• Aluminium Halter
• Euroseam 400, 0.9mm with
Rockwool Acoustic Membrane 5
20
25
30
35
40
45
50
55
60
Frequency Hz
Sou
nd
in
ten
sity
dB
PIR Composite
Standing seam, no RAM
Standing seam, 2 layer RAM
Standing seam, 3 layer RAM
Rain Noise Testing BRE
Summary of the results
n/a
76 dB 58 dB
Standing Seam roofing
No RAM
Sound intensity level, LIA
Reverberant sound pressure levels, LAeq Classroom
Reverberant sound pressure levels, LAeq Gymnasium
PIR composite
Panel
58 dB77 dB
55 dB
55 dB
62 dB
A – weighted acoustic measurements
2 layerRAM
3 layerRAM
44 dB
43 dB
n/a n/a
Not possible to measure at all frequency bands
Overall Summary of results
11 dB
11 dB
Improvement compared with PIR composite
Sound intensity level, LIA
reverberant sound pressure levels, LAeq Classroom
Standing seam
No RAM
Standing seam
2 layer RAM
18 dB
reverberant sound pressure levels, LAeq Gymnasium
12 dB 19 dB
A – weighted acoustic values
Profiled metal
cladding
21 dB 32 dB
22 dB 34 dB
n/a n/an/a
Standing seam
2 layer RAM
What does this
represent ?10dB reduction in acoustic terms is very significant.
It will approximately halve the
loudness…..
A further 10dB reduction will halve
the loudness again, and so on ……
Play
-10 dBStop
-20 dB
-30 dB
-3 dB
-6 dB
-9 dB
• Play – represents PIR composite cladding
Reduce by ………
• 10dB – profiled metal cladding
• 20dB – Standing seam + 2 layer RAM 5
• 30dB – Standing seam + 3 layer RAM 5
Acoustic demonstration
Summary of testing
The use of Rockwool within metal roof
constructions significantly improves acoustic
performance with respect to impact noise from
rain
…but is this not a well known fact ?
You have seen and heard for yourself! …
How does Rockwool offer this improvement?
• acoustic absorption
When used within metal lightweight
roof constructions the fibrous
structure of Rockwool insulation
provides very effective sound
absorption.
How does Rockwool offer this improvement? • acoustic isolation
When in direct contact with metal
cladding, Rockwool insulation offers
acoustic damping.
Rockwool Acoustic Membrane in direct
contact with metal cladding provides
enhanced acoustic damping which will
significantly enhance acoustic
performance.
.
How does Rockwool offer this improvement? • Mass
Rockwool Acoustic Membrane 5
offers an effective mass layer. Two
layers of this product are equivalent
in mass to a sheet of acoustic
plasterboard.
The addition of a mass layer to a
lightweight roof construction will
improve acoustic performance.