Are Fire Barriers required with expansion
joints?
Expansion joint gaps are physical breaks
in the continuity of construction and generally
extend (as a gap) through floors, walls,
ceilings and roofs.
As such they often compromise fire compartment
zones and in the event of fire act as chimneys
for the passage of toxic smoke and flame.
Hence,
some form of fire stopping is required.
The type of fire barrier required within
expansion gaps is a system that not only
inhibits the passage of flame
and smoke but also one that moves in response
to structural movement. The Reactofire range
of fire barriers are designed to complement
the React
range of expansion joints providing fire
protection and accommodating movement.
Can't I simply use a mineral wool blanket
and fire resisting sealant?
For smaller expansion openings - less than
50mm wide - a mineral wool backer and a
fire resisting sealant may seem acceptable,
however:
The
mineral wool material will not open as the
expansion gap opens and therefore the fire
integrity of the structure is
left dependant solely upon the sealant.
Shear
movement puts enormous strain upon the bond
line between the sealant and the substrate
and the
failure of this bond will compromise the
fire compartment.
Mineral
wool and sealant fire barriers are fabricated
on site and as such the integrity of such
a fire barrier system
depends largely upon site workmanship. These
are often installed in less than ideal conditions
with the result that
workmanship is compromised.
Should I use a proprietary fire
barrier?
Proprietary fire barriers, expressly developed
for use with expansion joints, are designed
to be 'fixed and forgotten'. They accommodate
the
movement and stop the passage of toxic smoke
and flame for a pre-determined period. As
they are independantly tested and factory-made
in an
ISO9000 environment, the vagaries of site
workmanship never arises.
Are there any Standards or Norms that apply
to Fire Barriers?
There are a number of International Standards
to which fire barriers are tested. Whilst
almost every country has its own test regimen
the most widely
accepted of these International Standards
are:
British Standard BS 476 Parts 20 & 22
‘Fire Tests on Building Materials
and Structures’.
US Underwriter's Laboratory UL2079 ‘Standard
Tests for Fire Resistance of Building Joint
Systems’.
