What is Thermowood

What is Thermowood? Here’s Everything You Need to Know 

If you’re looking for weatherproof, stable, and eco-friendly timber, Thermowood is a perfect choice. Our timber experts are here to answer any questions you might have about the thermal modification process, Thermowood’s properties, what projects it’s best used for, and if it’s right for you. 

What is Thermowood? 

Thermowood, also known as thermally modified timber, heat-treated wood, or thermal wood, is an enhanced timber cladding treated at extreme temperatures. This process alters the wood's chemical and structural properties, making it more stable and durable. While Thermowood can be made from various softwoods, at Covers, we use European Redwood (Red Pine) to ensure a high-quality, beautiful finish. 

How is Thermowood Made? 

Thermowood is created by heating timber to extreme temperatures, typically between 200-230 degrees Celsius, for many hours to extract as much moisture as possible. During this process, the wood is treated in steam, preventing it from cracking or splitting. Once the desired moisture level is achieved, the wood is rapidly cooled down. Since no chemicals are used, the resulting product is entirely natural. This heat treatment not only enhances the wood's durability and stability but also gives it improved resistance to decay. 

What Are The Properties and Benefits of Thermowood? 

The heat treatment process provides Thermowood with a wide range of useful properties such as: 

  • Long-Lasting: The heat treatment strengthens the wood's structure, making it more durable. Thermowood can withstand harsh outdoor conditions and has a longer lifespan compared to untreated timber.
  • Stable and Weatherproof: Thermowood is thoroughly dried, removing moisture and resin. This means it won't swell, shrink, or distort with changes in weather, temperature, or humidity. Being dimensionally stable makes it an ideal choice for outdoor applications like decking, furniture, saunas, and hot tubs.
  • Resistant to Mould and Rot: The heat treatment process breaks down hemicellulose in the wood, removing nutrients that mould and rot rely on to grow, making it highly resistant to these issues. 
  • Eco-Friendly: Thermowood is chemical and preservative-free, making it an environmentally friendly option. It's sourced from sustainably managed forests, and is PEFC Chain of Custody certified. It can also be recycled as untreated wood, making it a very sustainable option for your projects. 
  • Lighter Weight: With its moisture removed, Thermowood is lighter than untreated wood. This makes it easier to handle and install in various projects.
  • Natural Wood Finish: Thermowood offers a stunning, natural finish. If left untreated, it will naturally age to a light grey patina over time.

All these benefits do result in Thermowood coming with a higher price point, but for the right project, it is worth the investment. 

What Projects is Thermowood Best Used For?

Thermowood’s weather resistance, stability, durability, and natural finish make it a great choice for many internal and external projects, such as:  

  • Cladding
  • Flooring
  • Panelling
  • Decking
  • Furniture
  • Saunas and Hot Tubs
  • Summer Houses  

Does Thermowood Need to Be Treated or Sealed?  

Thermowood doesn't need to be sealed or treated, but it is more prone to colour changes and fading from sun exposure. To preserve its natural colour, applying a UV-resistant treatment is recommended. Thermowood can also be stained or painted if you prefer a different finish or colour. 

Does Thermowood Need More Maintenance? 

Thermowood requires less maintenance due to the heat treatment removing resin from the redwood timber, eliminating resin leakage or "bleed" through surface coatings. Thermowood's resistance to distortion and rot further lowers maintenance requirements, making it a long-lasting, cost-effective timber choice. 

What Sizes Does Thermowood Come In? 

Thermowood can come in a variety of types and sizes, at Covers Builders Merchants, we offer: 

Find Top-Quality Materials For Your Next Project 

Explore our selection of premium Thermowood cladding and other timber to get started on your next project. If you need any advice about finding the right materials for you, speak to our friendly, knowledgeable team who are always happy to help. 

Experience the difference of shopping at a family-run business with over 175 years of experience when you visit your nearest Covers depot.