Fire ventilation

Cross section of tin
plated roof structure.
88
persons should be available for this purpose. The size of the
fi re, the type of roof structure, and the choice of tools/method
will nevertheless determine how many persons are
needed. The safety aspects must also be taken into consideration,
and will be a decisive factor as to how the work
should be done, or if it can be done at all.
A few examples are given below of openings that can be
made in different types of roofs commonly found in Sweden.
It is a good exercise to make an inventory and to go
through the different types of roofs/structures that may be
encountered in fi re and rescue operations.
It is also important to bear in mind that the actual opening
should be made in such a way that there is always a safe
escape route, as described in the last chapter. The fi rst cut in
a roof should be made away from the work platform (ladder
or ladder truck), so that the last cut can be made while
standing on this work platform.
Tin plated roofs on older buildings
The tin plated roof is built up as follows, from the inside to
the outside:
• wooden roof trusses
• wooden roof boarding
• roof base paste board, where appropriate
• seamed metal sheeting
The opening is made between the roof trusses. On roofs with
seamed metal sheeting it is diffi cult to see where the roof
trusses are. On certain buildings they may extrude at the
base of the roof. There is often metal jointing or other metal
objects just beside the roof trusses, ridge and base of the roof.
Leave an edge of one to two decimetres from these.
To make an opening for fi re ventilation the seamed metal
sheeting can be penetrated in different ways. One way is to
cut it by means of a power cutter, and if the power cutter is
powerful enough it will also be possible to saw through the
roof boarding at the same time. For the power cutter to
work effectively it must be run at full speed. It should work