Soon the first timber facades will be built at height without fire-retardant treatment

Published: 01.05.25

With the BioFacades:UpHigh project, DBI (The Danish Institute of Fire and Security Technology) has gained valuable knowledge about material use, and the first developers are already applying the project’s findings to real construction projects. This marks an important step toward widespread use of bio-based facades in taller buildings.

There is uncertainty surrounding the long-term properties of fire-retardant-treated timber for exterior use. The goal of the BioFacades:UpHigh project was therefore to determine whether it is possible to construct multi-storey buildings with ventilated timber facades – without fire-retardant treatment or sprinklers. At the same time, the project aimed to design facade constructions that prevent fire from spreading more than one floor above the point of origin.

“To achieve this, we worked with non-combustible elements in the facade, facade projections, flame deflectors, and fire stops. Omitting fire-retardant treatment and sprinklers places entirely different demands on execution and detailing around fire stops and flame deflectors,” says Mia Fossing Frederiksen, Project Manager at DBI.

The methods were applied to 10 different facade constructions, which were tested in full-scale fire tests based on a draft of the upcoming European facade standard. Five partners participated in the project, each with access to two facade tests where they had free rein to design and test their chosen solutions. Three of the partners were developers involved in large, innovative projects within Fire Class 4.

“This meant some facade designs were highly experimental, while others were tied to specific construction projects with intended real-world use,” says Mia Fossing Frederiksen.

Highly varied test results

The test results turned out to be very different. While some constructions failed dramatically, others passed with a comfortable margin or needed only minor adjustments to meet requirements.

“But there were no right or wrong outcomes in this project, as we were experimenting and testing to gain knowledge. And we certainly learned a lot. Among other things, we now understand much more about how materials behave,” says Mia Fossing Frederiksen, elaborating:

“For example, we found that no constructions performed well when combustible materials were used in interior corners. We also discovered that paint on steel elements could lead to fire spread, while painting the wood itself had no significant negative impact. Additionally, we gained great experience with testing under the draft European standard and improved our advisory capabilities. We’re now stronger both in testing and in consultation,” she adds.

A benefit for the industry

Facades have traditionally been a complex area, and one of the goals of the BioFacades:UpHigh project is to share testing experiences with the construction industry.

“We want to provide the industry with a foundation so they don’t have to start entirely from scratch when designing and testing bio-based facade constructions. At the moment, there are no documented solutions in this area, so any construction with a bio-based facade that falls outside pre-approved solutions – and that doesn't use fire-retardant treatment or sprinklers – is automatically classified as Fire Class 4. And that can be costly. That’s why we hope our test results can serve as a basis for similar facade constructions within Fire Class 4,” says Mia Fossing Frederiksen.

And the project has already shown results – one customer has already conducted a fire test for a specific construction.

“The tested facade consisted of bio-based materials and included a flame deflector. No fire-retardant treatment or sprinklers were used, which were key requirements of the project. The facade passed the test, and the construction it will be used in may already begin next year,” says Asmus Haastrup, Project Manager and participant in BioFacades:UpHigh.

“We’ve also had inquiries from several other clients who want to test similar facade constructions for specific building projects. And we’re in dialogue with international stakeholders who are interested in our test results. So the project has definitely had the impact we hoped for,” Asmus Haastrup adds.

Still a way to go

However, the project’s 10 fire tests are far from enough to establish pre-approved solutions in the field. So there's still room for further development and documentation of bio-based facade solutions.

“Fire-safe design solutions involve a combination of many factors. That means we need to conduct more tests, where we don’t change many variables at the same time, but instead tweak only small details in each test. That way, we can better see what works,” says Mia Fossing Frederiksen.

“We’re currently working on a new section for our website where architects, developers, fire consultants, and others can access easily digestible materials from the project. For example, there will be a white paper with conclusions aimed at fire consultants, along with all test reports, best practices, and more, which will be made available to the industry,” she concludes.

Learn more about BioFacades:UpHigh, and explore the test results and videos

Read also: Biofacade lasted for 11 minutes

Read also: Fire tests reveal the potential of wooden facades in high-rise-buildings