Different countries world-wide have different legislation concerning the performance of facades exposed to fire and often significantly different ways to assess this performance. Although it is recognized that standard façade fire testing aims to distinguish façade systems that limit fire spread to an acceptable level from systems that do not, it has historically been considered important that the fire exposure of such tests is representative for real fires.

In this study five real scale compartment fire tests, constructed of Cross Laminated Timber and Glued laminated timber were performed with instrumentation on a façade extension above the ventilation openings, providing a means to compare façade performance tests against the exposure generated by realistic compartment fires. The fuel load and openings of four of these tests were determined from a statistical analysis to represent severe fire exposure within a realistic range. Of these tests the surface areas of exposed Cross Laminated Timber and Glued Laminated Timber were varied, allowing an assessment of the influence having internal areas of exposed timber surfaces on the façade fire exposure.

For these tests, an increase of roughly 40 m2 exposed surface area (from ~54 to ~94 m2 or from 113 % to 196 % of the floor area) resulted in a temperature increase of roughly 100 to 130 °C at the façade at all heights up to 3.5 m above the opening. Additionally, an increased fire plume height of 0 to 1 m was observed. The most significant effect of increased exposed areas was a prolonged duration of the flashover phase.

The British BS 8414 standard façade fire tests and the recently proposed European façade fire test have been identified to be the most representative for the tested residential fire scenarios in terms of façade fire exposure. Temperature measurements of the North American methods (NFPA 285 and CAN/ULC-S134) are towards the end of the tests also close to the those of the compartment tests. The Swedish SP Fire 105 test imposes the lowest exposure for a relatively short duration to the façade. It should, however, be noted that a lower exposure in the standard test method does not with necessity mean lower threshold for regulatory compliance as the test criteria also differ between different countries.

One of the tests were characteristic of open plan office buildings and it was shown that the fire exposure is both shorter and lower compared to typical residential compartment tests. All standard tests that were used for comparison here exhibited both longer and higher exposure than the office building compartment test.