The Steel Construction Institute (SCI) has released a revised edition of Publication 442, ‘Design of Loadbearing Light Steel Walls Exposed to Fire on Two Sides’.
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The original version of Publication 442 was released in 2024 to address the pressing need for a structural design method for load-bearing light steel walls exposed to fire on two sides. The publication and design methods have been a great success and have been widely adopted and accepted by industry.
However, since the release of the original publication, SCI has conducted a further ad-hoc two-sided fire test to extend the supporting information for the P442 design method. The latest ad-hoc test was on a load-bearing light steel framed wall with three layers of 15 mm British Gypsum Fireline plasterboard attached to each side of 100 x 50 x 1.25mm lipped C section studs. For this wall construction the test failure duration was 123 minutes.
Validation and confirmation
The new test data were used to further validate the P442 design method and confirm its suitability for use in the design of load-bearing light steel walls exposed to fire on two sides. There were no changes required to the design method as a result of the additional test evidence. The revised publication gives further details of this additional test and the original ad-hoc two-sided fire test in a new appendix. The changes to the revised edition of P442 compared to the original publication are:
• The inclusion of Appendix C, which gives details of the background ad-hoc fire tests which were used to develop and validate the design method
• New artwork for the front cover image to differentiate it from the original version.
Load-bearing light steel frame walls are used in the construction of various types of multi-storey buildings. The walls are typically fire protected using multiple layers of gypsum-based boards depending on the required fire resistance period. Their fire resistance is demonstrated by fire testing of loaded walls exposed to fire from each side separately in accordance with BS EN 1365-1.
Compartment walls at the boundary of a fire compartment are only exposed to fire from one side at a time because design is based on the principle that a fire is contained within the fire compartment and does not spread to other compartments within the defined period of fire resistance. However, walls within a fire compartment could be exposed to fire on two sides simultaneously unless there are measures in place to prevent the spread of fire within a fire compartment. Hence, the need for the design methods presented in P442.
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