In recent years the use of wood as a building material has become popular, especially for dwellings. One of the preconditions for its use is adequate fire safety. Technical measures, especially sprinkler and smoke detection systems, well equipped fire brigades and a better knowledge in the area of structural fire design of timber structures allow the use of timber in a wider field of application. Full scale tests on wooden modular hotels were performed under natural fire conditions to look at the efficiency of different fire safety concepts. In a first series the efficiency of technical measures, especially fast response sprinkler systems, was studied. The second series showed the possibility and limits of structural fire safety measures. Special attention was given to the influence of combustible room surfaces on fire growth and fire spread inside and outside the room. The tests enlarged the experimental data for validation of natural fire simulations (temperatures, fire spread etc.) and for verifying the methods for the fire resistance calculation of wood constructions.