Experimental study of the fire performance of wooden facades

Abstract

Abstract. The paper presents an overview of test results of 21 full-scale tests of wooden facades which were performed during an Austrian research project [1]. These tests were carried out according to and were the basis of Austrian classifications without further testing of the fire performance of wooden facades [3]. FIRE SCENARIOThe spread of a fire on a facade is influenced by both the location of the initial fire and its intensity. Actual fires as well as several fire tests have shown that a fire inside a building with a flashover has the most detrimental effect on the facade. The Flames reach lengths up to 5 m. The length of the flames depends on the fire load, the size and the geometry of the windows. They generally reach heights of two floors above the fire source, given a conventional height of the floors.The general safety goals are to ensure the load bearing capacity of the building over a defined duration, to avoid spread of fire to other buildings or fire compartments, to ensure the escape or the rescue of inhabitants and the safety of the rescue team. Based on these general safety goals the Austrian building authority demands no fire spread over more than one storey above the fire source over a period of 30 minutes [5]. Additional requirements include the temperature in the ventilation voids and the prevention of the collapse of larger parts.In former times the influence of wooden facades to the fire spread had been discussed. Some experts were afraid of the combustibility of these facades and of their influence to the fire. Kotthoff [4] carried out some natural fire tests of wooden facades and wooden balconies on a four storey high building in Merkers. These tests were part of an international project with Swiss, Finnish and Austrian participation. The tests have proved that there is no significant influence of the combustibility of the wooden facade, if the ventilation voids were sealed with fire barriers. After the burnout of the fire load in the initial floor the fire at the facade decreased and after 60 minutes the fire stopped without extinguishing. Based on these tests and some additional full-scale tests guidelines with technical solutions of the fire barriers in the ventilation cavities for Switzerland [6] and Germany [7] have been published. While there may not be a fire spread over more than one storey above the fire source over a period of 30 minutes in Austria, in Germany this limit is one storey higher and the period is only 20 minutes. Due to these different safety goals additional tests with stricter solutions were needed. However, Kotthoffs test results were very important for the discussions with representatives of building regulations and fire brigades.In Austria the use of fire barriers for ventilated facades and also for ETICś is required for buildings with more than 3 storeys. The results of the research project and the developed constructive solutions were essential for buildings with more than 3 storeys. TEST METHODESThe Austrian tests were performed according to . Differing...

Structural Means for Fire-Safe Wooden Façade Design

“…Based on the Swiss results, an Austrian research team investigated five further wooden fac¸ade systems and fire stops on a fac¸ade test stand in accordance with O ¨NORM B 3800-5 [16,27]. In summary, the results reflected the following findings [14] (Table 2).…”

“…Numerous research projects have identified fire stops as essential design measures in limiting the spread of fire on wooden fac¸ades to an acceptable level [13][14][15][16][17][18][19][20].…”

“…During the observations for Test 5, it became obvious that fire spread across the horizontal fire stop may occur even though no direct exposure by flames exists, as shown in Figs. 16 and 26 of the appendix. This fact can be explained by three factors.…”