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Fire safety of Honka log houses

Massive wood is a surprisingly fireproof material that can endure fire even better than concrete or steel pillars. Wood contains about 15% of water. Therefore, before wood can catch fire, all water has to evaporate. In a fire, a massive wood house will char, but it will not collapse in the same way as light- or steel-structured houses.

Surface charring also protects wooden structures. The charcoal generated in the combustion process has a much lower thermal conductibility than the wood itself and forms a natural insulating layer during a fire. This protects the wood from becoming even hotter, while the load-bearing capacity is retained practically unimpaired.

In contrast, steel loses most of its load-bearing capacity at temperatures as low as 500°C and has to be encased in other construction materials to achieve fire safety characteristics similar to those of wood.

We have been working intensively on the tightness of log houses for a long time. Tightness is very important not only for the living comfort and energy consumption but also for the fire safety of a building.

Jukka Rintamäki, R&D, Engineer

Tested and certified

All Honka logs have been tested on official fire-load tests by VTT Technical Research Centre of Finland. The test results are surprisingly good compared to timber frame houses and steel structured houses. In practice, this means that a log house made of massive wood gives its inhabitants more time to escape a fire as its load-bearing structures can withstand the heat for a long time without collapsing.

• Fire resistance of Honka log walls can be up to 2 hours
• The tightness of the walls can protect from the toxic smoke gases up to 1,5 hours


In the test, the Honka Fusion wall structure achieved the REI 90 fire resistance class. REI 90 means that the structure can be used in demanding buildings where load-bearing wall structures must be tight, insulated against a rise in temperature and able to withstand a fire for 90 minutes.

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