Thermowood – thermally modified wood

What is thermally modified wood

What is thermally modified wood?

Naturally enchanced wood using only heat and steam

How did the wooden Viking ships endure the corrosive effects of salt water? Nordic seafarers used to treat their wood with fire. Our contemporary understanding of thermally modified wood comes from the Finns who established thermal modification technology in the 1990s. So what exactly is thermally modified wood? In a nutshell, it is wood that has been made exceedingly more durable by modifying it with heat.

In addition to increasing its durability, thermal modification adds a number of properties to the wood that make it a highly sought-after building material. With improved dimensional stability, the wood will stop reacting to changes in humidity, which is why it is an excellent material for yacht sector. The wood simply absorbs less moisture than unmodified wood; it has a reduced risk of mildew and mould, and it endures heat better. All this while retaining the natural properties of wood with several improved features, including a beautifully deep and even tone.

Thermal modification is a bit like baking bread. The process takes place in a specially designed oven – a thermokiln, where sensors send information into computers that are constantly monitored by thermal modification specialists.

In order to assure the highest quality, we are collaborating with the world leading Estonian thermowood manufacturer Thermory where special thermal modification formula is used, which is the result of 15 years of hard work and experience. However, all thermal modification producers follow the same principle: within max 48 hours the temperature of the wood is raised up to 215 degrees, reducing the equilibrium moisture content, which is followed by a cooling process. No chemicals are used in the process, only heat and steam.

The most commonly used timber is ash and pine. Thermo-Ash has a rich chocolate colour. Thermo-Pine is more honey-coloured. Exposure to sunlight also has an effect on the colour of thermally modified wood: just like unmodified wood, it will turn silver-grey without regular protective maintenance.

Thermally modified wood is an environmentally friendly and eye-catching material with enhanced properties that is excellent for yacht sector.

Thermally modified wood is the most reliable option if you’re looking for a durable and dimensionally stable material for extreme weather conditions. The high temperature of thermal modification changes the structure of the wood, significantly improving its durability and resistance to weather conditions.

  • The biological resistance of the wood increases as the nutrients in the wood become more difficult to reach for pests and molds.
  • The wood’s moisture absorption capacity and speed decreases, resulting in reduced moisture deformations. The wood maintains its dimensional stability, meaning that it doesn’t cup, twist or bend as much as other wooden decking products.
  • Thermal modification leads to less internal stress in the wood, significantly reducing material consumption during construction.
  • The thermal and sound insulation performance of the wood improves.
  • Heat treatment also gives the wood a delightful darker tone.
  • Thermal modification is chemical free.

Certification and testing

We are are using only wood that comes from sustainably Managed forests.


Hardwood Sustainability

Supplies of certified slow growing tropical hardwoods suitable for outdoor use are becoming increasingly limited, resulting in illegal logging which, in turn, leads to the deforestation of tropical rainforests. Conversely, in temperate regions such as in Europe the net forest area has been increasing steadily for several decades, thanks to faster growing species of trees and responsible forest management.

Tropical hardwoods take many decades to mature, and some are not suitable for logging for well over 100 years. With a service life of only a few decades once manufactured into finished products, it’s clear that this cannot be a very sustainable approach to preserving the world’s tropical rainforests.