Scaled fire testing leads to successful full-scale bio-facade testing

Published: 13.11.23

The third construction in DBI’s BioFacades:UpHigh easily passed a full-scale facade test. This was preceded by a number of downscaled fire tests and adjustments along the way, which proved to be very successful.

The goal of DBI’s BioFacades:UpHigh project is to prove that it is possible to build multi-storey buildings with ventilated wooden facades without using impregnated wood or sprinklers, instead preventing fire from spreading on the facade using solely constructive design solutions.

“In this project, we’re investigating whether facades can be made with bio-based materials that are designed to prevent the spread of fire on the facade. In other words, we're making fire safety a design parameter from the start,” says Asmus Haastrup, Research Consultant at DBI – The Danish Institute of Fire and Security Technology and manager of the project alongside Mia Fossing Frederiksen.

In the third of the ten bio-based facade tests to be carried out in the project, DBI managed to design a construction that prevents the spread of fire on the facade. Two layers of wood-fibre wind-barrier boards of 12.5 mm each were used, covered with a thin, non-combustible and breathable fabric. Behind the wind barrier was 240 mm of wood-fibre insulation, while on the outside was a rain screen in untreated spruce. Mineral insulation, extra structural timber and a non-combustible wind barrier were laid in each storey, but apart from this the only non-combustible part of the facade was the steel flame deflectors, which extended 32.4 mm beyond the rain screen.

“We stopped the test after 60 minutes. By then, the construction had passed the test and it was clear that this was now a smouldering fire that wouldn't develop any further. So it was rather fantastic,” says Asmus Haastrup.

Down-scaled fire tests

There are five partners in the project, each of whom is in charge of two of the ten facade tests, free to design the facade solutions they want and to run the process in the way they see fit. CPH Village was behind the third and very successful test, which is part of a construction project that will end in a number of sustainable student housing units in Copenhagen.

“We can only praise the developer for the process that led to such a good result. CPH Village chose to pay for a total of seven 50 x 50 cm small-scale tests as well as a down-scaled facade test, allowing us to learn along the way and to make continuous adjustments before the full-scale test,” says Asmus Haastrup, going on to explain:

“Among other things, we tested several versions of a wind-barrier board with only one layer of insulation and a wind-barrier plasterboard with insulation, which failed in terms of charring or temperature, or both. In addition, we carried out a downscaled facade test to see how the fire would spread through the insulation and how we should create the detail between the storeys (fire stop), which leads into the facade,” he says.

Dedicated developer

Janne G. L. Frederiksen, manager in DBI’s consultancy department and fire safety consultant for the student housing project, also points to the process:

“The successful test was only possible because CPH Village has been very dedicated to the task and has had the willingness – also financially – to work with the design and small-scale testing. This meant that we were able to adjust, fine-tune and test on a small scale before testing on a full scale,” says Janne G. L. Frederiksen, adding:

“With this test result, CPH Village can now use this as a fire class 4 facade in their student housing project. At the same time, we've opened the door and gained even more knowledge that we continue to build on to take our work with bio-based construction even further.”

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The goal of the project is to prove that it is possible to build multi-storey buildings with ventilated wooden facades without using impregnated wood or sprinklers if the facade is designed to prevent fire from spreading in the first place. A total of ten tests will be conducted on various wooden facades over the course of the project. All of these tests will be conducted in accordance with a draft of the new European-wide facade testing standard, which is on the horizon.

Besides DBI, the developers NREP, Fælledby and CPH Village are participating in the project, as well as the manufacturer Frøslev Træ. The goal of the project is to generate documented solutions that prevent the spread of fire. The intent is to pave the way for wooden facades on three actual, innovative buildings from the three developers and result in a catalogue of design recommendations for wooden facades on multi-storey buildings.

The project’s total budget is DKK 6.6 million and is supported by Realdania and the Danish Agency for Education and Research via DBI’s performance contract. The project started in November 2022 and will continue until the end of 2024.

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Biofacade lasted for 11½ minutes

Asmus Haastrup
Research Consultant

+45 50 80 65 25