Improving fire safety in wood construction with lignin-based solutions

Fire safety is one of the key challenges in wood construction. To address this challenge, we have developed lignin-based adhesives and coatings that improve the fire performance of wood and open up new applications for a by-product that has so far been utilized only to a limited extent.

The wider adoption of wood construction is limited in particular by fire safety concerns. Wood is a highly flammable material, but due to its charring properties, it can be made quite fire-safe when combined with suitable coatings, impregnations and adhesives.

In Towards carbon neutral lignin-based fire protection solutions (Lignis) project wedeveloped solutions to improve fire safety in wood construction by utilizing lignin-based materials. Lignin is a byproduct of pulp production, and there have not been many applications for it to date. In fact, a large portion of the lignin produced often ends up as fuel for local energy production.

We studied lignin-based adhesives, coatings, and impregnations, as well as their effects on the fire properties of wood. The main raw material for the project was a sub-micrometer-sized lignin sphere commercialized by LignoSphere Oy. Whereas lignin separated directly from a pulp mill is poorly suited for use as an adhesive or coating, spherical lignin enables the production of high-quality adhesive and coating formulations.

In the Lignis project, we improved a lignin-based adhesive to meet the industry standards. This allows it to be used in commercial end products, such as structural wood adhesives used in the manufacture of glued laminated timber and cross-laminated timber (CLT). In collaboration with Kiilto Oy, we also developed a lignin-based polyurethane adhesive that does not melt at high temperatures when used in CLT production. This feature is critical, especially when constructing tall wooden buildings, as they must remain safe even in the event of a fire.

The development of a lignin-based coating we studied during this project is continuing in the Biopigment project.

Towards carbon neutral lignin-based fire protection solutions (Lignis) project was implemented in collaboration with Aalto University, LignoSphere Company Oy, Kiilto Oy, Aureskosken Jalostetehdas Oy and Versowood Oy between 1.12.2023-28.2.2026.

The project was co-funded by the European Union.