Civil Engineering Reference
In-Depth Information
Chapter 8.2
Fire doors
The main purpose of fire doors is to
protect openings in fire walls built
either to separate parts of a building
or to enclose stairway walls, and
which could, if not protected, be
easily breached in fire (Figure 8.11).
Fire doors can greatly limit fire
damage by keeping smoke and
flames from spreading. However,
they cannot function if they are left
open, unless they are held by
magnetic or other types of catches
which release automatically in the
event of a fire occurring. Accidental
damage so that they will not close
properly is also a possibility which
must be guarded against.
The precise role of any fire door
will depend on whether it is intended
to protect escape routes from the
effects of fire, or to protect the
contents or the structure of a building
by limiting fire spread. Some doors
may therefore need to fulfil only the
first function, others the second. In
many cases both requirements will
apply
(224)
.
Characteristic details
Basic structure
The industry has successfully
developed door assemblies using
widely different forms of design, and
it is therefore not appropriate to
attempt to give a simple listing of the
these various kinds of construction,
although some indication of typical
construction may be useful.
The door and its frame may be of
any construction which passes a fire
resistance test. However, in order to
be satisfactory, the door should be
reasonably straight and true and lie
flush against the stop when closed; in
earlier years, the gap between the
door edge and the frame would not
have exceeded 3 mm, and the door
frame would have had a rebate or
stop not less than 25 mm deep, but
those criteria do not now
necessarily apply.
The door furniture is of
importance. There would usually
have been at least one pair of metal
hinges, all parts of which would have
been non-combustible and which had
a melting point not less than
800 °C. The lock or latch typically
would have had a brass or steel
tongue which engaged into a brass or
steel latch plate or keep for a
minimum distance of 10 mm when
the door was closed. Rim locks
would have been mounted on the
non-risk side of the door or bolted
through the thickness of the door.
Any plain glazing would typically
have been of at least 6 mm wire
reinforced glass not exceeding 1.2 m
2
in area and fitted with solid wood
beading not less than 13 mm in cross-
section.
Figure 8.11
The head of the doorway on the left has been breached, and the double doorway ahead
shows evidence of smoke infiltration. The fire is out and the investigation is beginning
