Fire ventilation

chapter 8
Openings in different
roof structures
There is no general method for creating openings that can
be applied for all the different types of roofs that are
encountered. More simple roof structures with a framework
of wood or metal can often be dealt with relatively
easily during a fi re ventilation operation, while roof structures
that contain thick concrete or steel must be considered
to be impenetrable in such contexts. Nevertheless there
are tools that can cut through concrete, for example the
hydraulically powered eccentric cutting machine. Creating
openings in such materials does take a long time, and is
therefore only applicable in very special situations.
If fi re ventilation is to be worth the effort it is essential
that both the outlets and inlets are suffi ciently large. The
size of the fi re and the premises are the determining factors,
but for an outlet 4–8 m 2 can serve as a guideline.
It takes time to create openings for fi re ventilation, and
regardless of which method is chosen and used the time
factor must be taken into consideration. The fi re develops
and changes over time, and this means that the situation
could be completely different when the openings are ready
from what it was when the work was started or a decision
was made.
The fi re and rescue operation must be coordinated if fi re
ventilation is to be successful. The team participating in the
operation should be experienced and trained in the use of
the tools and the methods applicable for creating openings
in different roof structures. At least two, or preferably three
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