We recently took a trip to Finland to get a close, in-depth look at the thermal modification process and the ever-popular Thermo-Nordic Pine.

A winding two-lane road curves to the right through a dense forest, with trees lining both sides and a cloudy sky overhead.

The journey began at 4am Sunday morning, with a five-hour flight to Helsinki via Amsterdam.

Greeted by the autumnal Finnish air and our host for the trip, we made our way north into the remote pine forests of Mantta-Vilppula.

Did you know? Finland is dominated by Scots pine and Norwegian spruce, which make up roughly 80% of Finland's forest area.

Tall evergreen conifer trees form a dense forest against a light blue sky with scattered white clouds.

After 260km (161 miles), we pulled up to a traditional log cabin to receive a warm Finnish welcome, some traditional food - including kalakukko, fish baked inside a loaf of bread - and of course a traditional Finnish sauna.

Gravel road curves through a dense forest of tall evergreens and deciduous trees with autumn yellow leaves; sunlit gaps filter through the trees.

Well-rested after a good night’s sleep, we met with our US-based client, an innovative modular home builder from Los Angeles.

We’ve been working closely with them as they bring their vision to life, which combines pioneering engineering with cutting-edge technology to achieve an impressive build time of just three months.

All present and correct, we made our way to the ThermoWood® thermo-treatment yard to get a close look at the process.

Stacks of wooden planks on pallets at an outdoor lumber yard, with a forest and lake in the background under cloudy skies.

ThermoWood® pioneered the thermal modification process in the 1990s, as researchers set out to create a natural alternative to chemical treatments for timber.

Developed by the VTT Technical Research Centre of Finland, the process uses heat and steam to transform locally-grown species, such as Scots pine and spruce.

The heat causes hemicellulose - a sugar that decay-causing organisms feed on - to break down. In turn, this improves the wood's resistance to decay. The process also alters the sites that bond with water, improving moisture resistance and stability.

This pioneering technology became the ThermoWood® process, later managed by the International ThermoWood Association.

Stacks of lumber planks outdoors beside a red metal-roofed warehouse, with trees and a cloudy sky in the background.

During the visit, our hosts shared more about their origin story.

Interestingly, the family business began in beef farming, but with a desire to diversify, they spotted an opportunity to industrialise the thermo-process. Teaming up with a local sauna maker, they designed and built what is believed to be the first thermo-kiln, crafted from a storage container, over 30 years ago.

Since then, they have continued to spearhead the evolution of the industry.

Outdoor lumber yard with stacked wooden boards and pallets, brown sheds, a paved lot, and a forest of evergreens under a cloudy sky.

Today, ThermoWood® is exported worldwide and is recognised as the original benchmark in thermal modification, offering sustainable, high-performance timber with a distinctly Nordic heritage.

Stacks of brown wooden planks bound in bundles with metal bands; a blue strap hangs among them beside a vertical wooden wall.

As we explored the site, we got a close-up look at their highly developed thermo-chamber (kiln), where the timber is placed ready for the thermo-process.