This report describes three case studies that each involved an analysis of a fire test of an external wall that included a timber structure or part of a timber structure. These external walls all had wooden façade panels, were ventilated behind the façade panels and had glass wool or stone wool insulation. The three case studies aim to assess the contribution of structural timber to the fire development and the fire spread. In addition, the potential of façade systems with combustible materials to limit the fire spread through and along the external wall was assessed. The fire tests were performed for commercial purposes and their results were made available for this study. Not all details of the façade systems details are included in this report.

The analysis discussed in this report indicates that the timber structures did not contribute to the fire development and the fire spread in two of the three tests. The structural members in the external wall remained unaffected during the test. Visual inspection of the third test showed locally some superficial coloring and charring. However, the temperature measurements of the remaining test did not indicate any contribution of the structural timber to the fire development and fire spread. The energy contribution corresponding to the local and superficial coloring and charring is considered negligible.

Two of the three tests analyzed in this study were performed in accordance with the Swedish façade fire testing standard SP Fire 105. Both tests were assessed by the accredited testing institute to meet the requirements set by the Swedish Building regulations that: (1) the fire spread inside the external wall shall be limited; (2) the risk for fire spread along the façade surface shall be limited and; (3) the risk for injuries as a consequence of falling parts from the external wall shall be limited.