Tips
How to Identify Quality Thermally Treated Wood Before Buying
When choosing wood for a terrace, facade or other outdoor structures, people often focus on appearance or price. In practice, the most important question is how the material will perform after several seasons. Outdoor wood is constantly exposed to moisture, temperature changes and sunlight. Because of this, stability and resistance to environmental impact are among the most important factors.
For this reason many architects, builders and homeowners choose thermally treated wood. This is natural timber that has been modified using only heat and steam. During the thermal modification process the wood is heated to approximately 180 to 220 °C. This treatment changes the internal structure of the wood and reduces its ability to absorb moisture. As a result the material becomes more stable and less likely to warp.
In simple terms, thermally treated wood is designed to perform better in demanding outdoor conditions than untreated timber. Even so, the quality of products on the market can vary. Before buying it is useful to understand the main characteristics that indicate properly modified wood.
How to recognize quality thermally treated wood
Quality thermally treated wood usually shows several clear characteristics. The color of the boards is often the first indicator. A consistent brown tone usually suggests that the wood was modified evenly. Stability is another important sign because properly treated wood reacts less to humidity changes. Surface finishing also provides useful information, since well processed boards tend to have smooth surfaces and straight edges. Finally, the wood species itself influences strength and durability.
Consistent natural color
One of the easiest quality indicators is the color of the material. Thermally treated wood develops a deeper warm brown tone during the modification process. This change is a natural result of the high temperatures used during treatment.
High quality boards usually display a relatively consistent shade across the entire surface. Minor differences are normal because wood is a natural material. However strong contrasts or pale areas may indicate uneven treatment.
Stability and resistance to warping
The main advantage of thermally treated wood is improved stability. Thermal modification reduces the hygroscopic properties of wood, meaning the material absorbs less moisture from the environment.
In practical terms this means the boards expand and contract less. They also maintain their shape more consistently and are less likely to crack over time. These properties are especially important in climates where temperature and humidity change throughout the year.
Because of this improved stability, thermally modified timber is widely used for terraces, facade cladding and other outdoor applications.
Surface finishing quality
Another aspect worth checking is the quality of the surface processing. High quality boards usually have smooth surfaces and precisely cut edges. This indicates that the material was properly prepared and machined.
Well finished timber is easier to install and helps achieve a cleaner and more precise final result.
Wood species also matters
The performance of thermally treated wood depends not only on the modification process but also on the species of timber used. Different species have different density levels and mechanical strength.
ESSPO Wood currently offers three main thermally treated wood species:
- Thermally treated ash is very strong and dense.
- Thermally treated pine – stable and versatile.
- Thermally treated spruce is lighter and visually appealing.
For terraces, thermally treated ash is often selected because of its strength and resistance to mechanical stress. For facade applications, thermally treated pine or spruce are frequently used thanks to their stability and natural appearance.
What to check before buying
Before making a final decision it is worth examining the boards themselves. The color should appear relatively even, the surface should be properly finished and the boards should be straight and stable. It is also important to choose a wood species that matches the intended use of the project.
Simple checks like these can help avoid future problems and ensure the material performs well for many years.
ESSPO Wood recommendation
When selecting thermally treated wood it is important to look beyond appearance. Stability, treatment quality and wood species all influence how the material performs over time.
If you are planning a project using thermally treated wood such as a terrace, facade or another outdoor structure, the ESSPO Wood team can help you choose the most suitable wood species for your project and its intended use.
Contact us – we will help you choose the best option!