MODIFIRE

In a joint project between Tampere University and South-Eastern Finland University of Applied Sciences (Xamk) our goal is to improve the fire performance of fire-retardant and modified wood products, develop test methods related to these properties, and expand the testing environments. The project is driven by the need to meet increasingly stringent fire safety requirements at both EU and national levels.

The focus of the project carried out at Tampere University is particularly on improving the fire resistance of adhesive joints in CLT (cross-laminated timber) structures and expanding the fire testing capacity for modified wood products.

Adhesive joints have a significant effect on the performance and durability of a CLT (cross-laminated timber) structure in fire conditions. The adhesive must be able to keep the lamellae of the product bonded together during a fire so that the char layer, which protects the wood from fire exposure, does not detach prematurely from the structure. The load-bearing timber frame of a building will char more rapidly if the adhesive used in the CLT structure loses its bond strength quickly. In addition to the adhesive itself, the behaviour of the joints is influenced by various gluing parameters, such as the amount of adhesive applied, the pressing method, and the treatment of the wood.

The performance of adhesives used in CLT elements at elevated temperatures can be investigated using several different test methods. However, in Finland and Europe, no clear guidelines or methods have yet been established for assessing the compliance of adhesive joints in CLT structures. 

The project will generate research-based knowledge on the effects of high temperatures on adhesive finger joints and adhesive bonds in CLT structures, and will assess the suitability of different methods for testing adhesive joints. The research activities will comprise small-scale heat-resistance tests on adhesive joints, as well as fire tests conducted in accordance with the Eurocode standard EN 1995-1-2:2025. Compared with full-scale fire tests, small-scale tests provide significantly faster and more cost-effective means of evaluating adhesive performance under elevated temperatures.

The tests will compare the fire behaviour of samples manufactured using different adhesives, bonding parameters and lamella thicknesses, as well as the temperature resistance of the adhesives themselves. Based on the test results, the objective is to identify a testing methodology that can strengthen RDI activities within the wood products industry by enabling more reliable prediction of the charring behaviour of laminated wood products. Furthemore, the research aims to assess the suitability of faster fire-testing approaches for evaluating the performance of finger-jointed sawn timber and CLT structures.

The project is co-funded by the European Union, with the grant awarded by the South Savo Regional Council.

Duration: 1.2.2025 – 30.6.2027

Total budget: 120 209 €

EU Finding: 96 167 €

Stora Enso Oyj and Kiilto Oy also participate in funding the research.