Combining fire and sound insulation
Plastic organic interlayers have no significant practical
resistance against fire. On their own they may actually
be at risk of burning. Thermal deterioration of organic
layers becomes increasingly rapid from about 150�C.
Such interlayers readily smoke, melt and flame when
exposed to flames and heat from a fire. "Safety" as
used to describe laminates based on polyvinylbutyral
(pvb), and like materials, refers to impact safety. This
should not be taken to mean safety in case of fire.
Similarly, security laminates are primarily intended to
prevent unlawful break in and they should not be
taken to imply security from the effects of fire.
The intumescent interlayer used in fire-resistant
glass such as Pilkington PyrodurTM (integrity) and
Pilkington PyrostopTM (integrity with insulation),
however, is a different interlayer. The interlayer is
glassy and inorganic, specifically designed for robust
fire resistance.
The acoustic benefits of the fire-resistant glass
range based on this glassy intumescent interlayer
derive from the thickness, asymmetric and damping
effects that are known to improve glass per-
formance for sound. These fire-resistant glass
laminates have good sound attenuation perfor-
mance as a result. Installing glazed panels of
Pilkington PyrostopTM and Pilkington PyrodurTM in
fire doors, primarily for fire performance and
through vision, can also improve the overall sound
insulation performance of the doors.
Fire-resistant glass floors
The striking advantages of intumescent fire-resistant
glass are demonstrated by the latest developments in
fire-resistant load bearing glass floors. A robust fire
performance and very effective acoustic properties
result from the multi-laminated structure of different
glass layers combined in one structural unit.
Such an innovative development produced by
Glazeguard in the UK is based on Pilkington
PyrostopTM for its fire resistance component. The
Glazeguard floor has recently exceeded 60 minutes
in an official fire test as a timber floor system under
load, having also previously achieved stable fire
performance and 60 minute classification in steel
framing (tested to EN 1365:2000, part 2). The
sound insulation Rw index for this glazed floor
structure is 48 (�1; �5), reference EN ISO 717. This is
a remarkable result and one that conclusively
demonstrates both the robust fire protection
and the effective acoustic contribution of the
intumescent fire-resistant glass technology.
Structural stability of glass floors
It is a critical requirement for a fire-resistant fire
floor that the load is capable of being sustained
20 INTERNATIONAL FIRE PROTECTION
FIRE RATED GLASS
Table 2: Example comparison of sound insulation performance for different glass products
Products not classified for fire resistance Sound attenuation index
Rw (C; Ctr), reference EN ISO 717-1, in dB
Pilkington OptilamTM (6.4mm standard laminate) 32 (�1; �3)
Pilkington OptiphonTM (6.8mm acoustic laminate) 35 (�1; �3)
Pilkington OptiphonTM 6.8mm in dgu, 16mm gap 38 (�2; �6)
Pilkington OptiphonTM 9mm in dgu, 16mm gap 39 (�2; �6)
Products classified for fire resistance Sound attenuation index
Integrity fire resistance Rw (C; Ctr) index, reference EN ISO 717�1, in dB
Pilkington PyrodurTM Plus (7mm, E/EW 30, EI 15) 35 (�1; �3)
Pilkington PyrodurTM (10mm, E/EW 30, EI 15) 36 (�1; �2)
Pilkington PyrodurTM 10mm in dgu, 12mm air gap 38 (�2; �5)
Pilkington PyrodurTM (13mm, E/EW 60, EI 15) 38 (�1; �2)
Products classified for fire resistance Sound attenuation index
Insulation with integrity fire resistance Rw (C; Ctr), reference EN ISO 717�1, in dB
Pilkington PyrostopTM (15mm, EI 30) 38 (�1; �2)
Pilkington PyrostopTM (18mm, EI 30) 38 (0; �2)
Pilkington PyrostopTM 18mm in dgu, 12mm air gap 40 (�1; �5)
Pilkington PyrostopTM (23mm, EI 60) 40 (�1; �3)
Pilkington PyrostopTM 18mm in dgu with Pilkington 45 (�1; �5)
OptiphonTM (9mm), air gap 12mm
Notes:
1. Further guidance and data available on request. Sound insulation data measured in accordance with BS EN ISO
140-3
2. Correction factors C and Ctr take into account the different frequency spectra of residential and traffic noises,
respectively.
3. "dgu" refers to a double glazed unit with a 6mm float glass pane unless otherwise indicated
4. Fire resistance classifications in accordance with BS EN 13501-2: E = integrity; EW = integrity and radiant heat;
EI = insulation performance; 30, 60 etc = classification test time in minutes
5. The Pilkington PyrodurTM and Pilkington PyrostopTM range are also classified for impact safety according to
BS EN 12600

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