Fire-performance of a ventilated facade insulated with a B2-classified rigid polyurethane foam

A two‐storey test rig was used to investigate how an insulated facade would react to the impingement of a simulated room fire. In particular, whether or not a facade insulated with polyurethane foam would promote vertical flame spread. Wooden cribs weighing 40 kg were used as fire sources. One set of tests was run without any steel cladding to study the behaviour of the polyurethane foam alone. In a wall‐configuration test as well as under a conrner‐configuration one limited vertical and horizontal flame propagation were found. The degree of damage was to some extent, greater under the corner‐test conditions than with the wall tests. A ventilated facade construction with the profiled steel cladding fixed to vertical support‐work was used for the second set of tests. In order to simulate repair conditions, the outer metal cladding was completely removed from the lower 1.5 m of the facade. In Both tests a strong chimney‐effect behind the cladding was observed. This intensification of the flame impingement led to a flame spread up the top of the facade. The tests indicated that the vertical flame spread would continue unless the method of construction incorporated vertical fire stops.