Wooden structures are the oldest building elements accompanying man since time immemorial. The Czech Republic is strict in its legal and normative regulations relating to the use of wooden building components. In spite of that the Czech construction market is increasingly returning to wooden houses; not only for dwelling purposes, but also for public amenities. However, the structures made of wood as combustible material have to be carefully assessed especially from the viewpoint of fire safety of the building. This paper deals with the fire safety of wooden structures with special regard to the suspended type of ceiling, as it fulfils the role of insulation against the effects of fire. In particular, the thermal stress caused by fire and its impact upon the safety of the building elements has been investigated.