Civil Engineering Reference
In-Depth Information
In order to achieve the full
30 minutes protection for fire
resistance, if not also for integrity, an
intumescent strip or strips will
probably need to be provided in the
edge of the door or frame, not in the
door stop, to seal the gap in the event
of fire. Indeed, timber doors cannot
achieve more than 20 minutes unless
an intumescent strip is fitted all
round. An additional hinge will also
typically be fitted, making one and a
half pairs.
If there is a glazed panel, beading
will probably be either of non-
combustible material which will not
melt or disintegrate at temperatures
below 900
shutters are also given by the Fire
Officers Committee
(225)
. The doors
and shutters covered by these rules
are intended primarily for use in
firebreak walls. Four rules are
specified for various types of
firebreak doors and shutters. Rules 1
to 3 are general construction
specifications for doors and shutters
to the Committee's own designs
while rule 4 is essentially a
performance specification for doors
and shutters of proprietary design.
The use of two doors in tandem
to close the same opening will
sometimes be encountered. Under the
Approved Document, it is permitted
to fit two doors, each of lesser fire
resistance than a single door,
provided that together they comply
with the requirement.
There are also special provisions
for doors enclosing lift shafts.
Main performance
requirements and defects
Choice of materials for structure
Many fire doors in existing buildings
will be of solid wood, or perhaps in
some cases of wood derivatives, or of
iron or steel sheet. A few wooden
doors may be found which in the past
have been upgraded with asbestos
insulation board; these doors will
require special treatment for removal
and disposal. Fire doors currently
supplied may be of any kind of
construction which passes the test.
Strength and stability
Fire doors should satisfy the impact
requirements of non-fire doors. See
also the same section of Chapter 8.1.
C, or of timber with a
metal capping, or of timber treated
with intumescent paint.
In addition, there should be a
self-closing device, although doors
fitted with these devices may be
held open by fusible links or by
other electro-mechanical or
electro-magnetic devices activated
by smoke.
Rules for the construction and
installation of fire break doors and
°
Dimensional stability, deflections
etc
Where doors and frames are made of
timber or timber derivatives, it is
important that they are not subjected
to dampness or condensation which
will affect the fit of the door. Fire
doors cannot usually be planed off to
ease fit, for example, when edged
with intumescent strips. Those which
warp will also tend be ineffective in
fire. However, it is as well to check
with the manufacturer whether slight
easing is permitted without
prejudicing performance.
For coefficients of linear thermal
and moisture expansion etc, see
Chapter 1.2.
Openings and joints
As already noted, the fit of the door in
its frame is crucial to performance -
the closer the fit, the more likely the
door is to achieve its purpose.
Thermal properties
Thermal insulation may be as
appropriate for fire doors as for
normal doors, depending on
circumstances. See also the same
section of Chapter 8.1
Fire
As already seen, the effectiveness of
a fire door depends on the
performance of the whole assembly
of door, frame and door furniture. In
the fire test, the assembly is judged
on the ability of the assembly to:
●
remain in position in the opening
●
prevent the passage of flame
through cracks or gaps
restrict excessive transmission of
heat
Figure 8.12
This pair of fire doors has survived quite well in a fire
●
