ThermoWood – why it's the best wood for a sauna

Choosing the right wood is one of the most important factors behind a sauna's quality, durability and comfort. Even the best design and modern fittings can't make up for a structure built from a material with poor properties. That's why at RoyalSauna we rely on timber that has been regarded for years as one of the finest materials for sauna building: ThermoWood.

It's this thermally modified wood that the shell and floor of our Compact, Comfort and Premium models are built from. Benches and headrests are aspen – a wood that stays gentle on the skin. That's no accident – the choice is backed by both the technical properties of the materials and decades of experience among Northern European sauna makers.

Why ThermoWood?

The thermal modification process treats carefully selected timber at high temperatures (180–230°C) using only heat and steam – with no chemicals whatsoever. This gives the wood exceptional durability and stability.

The heat-altered cellular structure reduces moisture absorption and removes resin from the wood. That's exactly why ThermoWood offers very good mechanical strength and high resistance to warping and weather conditions.

For the user, this means one thing: the sauna keeps its looks and properties through many years of intensive use.

Stability even at very high temperatures

Inside a sauna, wood works every day under exceptionally demanding conditions. Temperatures can exceed 100°C, and humidity changes within a very short time. Not every timber can handle that.

ThermoWood stands out for its very good dimensional stability. It moves far less under changes in temperature and humidity, which limits the risk of gaps, warping or deformation in structural elements.

This is one of the most important qualities of wood used in professional saunas.

Excellent thermal insulation

The natural properties of wood – strengthened by thermal modification – make it a very good heat insulator. ThermoWood walls keep heat inside the cabin, so the sauna reaches the right temperature faster and holds it for longer.

That translates into greater comfort and lower energy use while heating up – especially important for anyone who uses their sauna regularly.

A beautiful look for years to come

The natural appearance of the wood is one of the reasons so many people choose ThermoWood. After the heat treatment it takes on a warm, refined tone throughout, and the subtle grain creates a calm, elegant space that invites relaxation.

Every element keeps its own unique character, so no two saunas are quite alike. High-quality thermally modified wood is also resin-free and has a very even structure, which noticeably improves the look of the whole build.

Comfort in everyday use

Wood used inside a sauna should feel pleasant against the skin. That's why we make the benches and headrests from aspen – a species that doesn't heat up as intensely as many other materials and stays comfortable to the touch.

The wood's natural structure also helps the sauna's interior keep a pleasant microclimate, which has a positive effect on the whole session.

Durability proven by decades of tradition

Northern European countries have been world leaders in sauna building for decades, and it's there that ThermoWood technology was developed as the premier material for sauna construction.

Years of experience among manufacturers show that well-selected thermally modified wood performs beautifully even after many years of heavy outdoor use – which is exactly why producers focused on the highest build quality choose this material.

Wood that's kind to the environment

ThermoWood comes from responsibly managed forests where forestry is carried out with respect for nature, and the modification process itself uses only heat and steam.

Wood is a renewable resource that stores carbon dioxide and has a far smaller carbon footprint than many materials used in modern construction.

Choosing a sauna built from high-quality thermally modified wood means investing not only in the product's durability, but also in a more environmentally friendly solution.

Why did RoyalSauna choose ThermoWood?

At RoyalSauna, every material goes through very careful selection. Our goal is to build saunas that last for years, keeping their looks, durability and top level of comfort.

That's why we build the shell and floor of our Compact, Comfort and Premium models from ThermoWood. This wood combines outstanding looks, high structural stability, excellent insulating properties and resistance to the demanding conditions inside a sauna.

As a result, our clients get a premium product that keeps its properties through years of everyday use.

Summary

ThermoWood has been regarded for years as one of the best materials for sauna building. Heat and steam treatment gives the wood high dimensional stability, low moisture absorption and outstanding durability without chemicals. It insulates heat effectively, delights with its natural look, and performs beautifully under the demanding conditions of high temperature and changing humidity.

That's exactly why RoyalSauna uses thermally modified wood in the Compact, Comfort and Premium models. It's a deliberate choice built on quality and experience.

The best sauna begins with the best wood.