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Home > Hub > Thermally Modified Decking

Thermally Modified Decking:

A Complete Guide to Choosing the Right Timber

Thermally modified decking is a smart choice for customers looking for a natural timber deck with improved stability, durability and long-term visual appeal. By using heat and steam to enhance the timber, the process helps create decking boards that are better suited to outdoor conditions while still retaining the warmth and character of real wood.

At Southgate Timber, our thermally modified decking range includes options to suit different projects, budgets and design styles. Whether you are looking for the premium finish of Thermo Ash, the clean practicality of Thermory Spruce, or the cost-effective appeal of Thermowood Pine, this guide brings together the key product pages, advice articles and supporting content to help you choose the right solution.

Explore the benefits of thermally modified decking, compare product options, and find guidance on installation, maintenance and design ideas for modern outdoor spaces.

Our Decking Range

Thermo Ash Decking

A premium thermally modified hardwood with a rich tone, excellent stability and a refined finish that suits contemporary garden designs.

IN STOCK - CLICK & COLLECT OR QUICK DELIVERY
  • Smooth planed finish
  • High stability & low movement
  • Rich brown tones
  • Durable & long lasting
  • From: £14.49 small
  • £104.99 sq metre +VAT
Explore guide
Thermory Spruce Decking

A practical and attractive modified timber decking board with a warm natural look, ideal for modern patios, terraces and family gardens.

IN STOCK - CLICK & COLLECT OR QUICK DELIVERY
  • Smooth planed finish
  • Improved dimensional stability
  • Light golden brown colour
  • Consistant quality
  • From: £10.25 metre
  • £56.58 sq metre +VAT
Explore guide
Thermowood Pine Decking

A cost-effective thermally modified decking option that offers natural timber appeal, improved stability and strong value for outdoor projects.

IN STOCK - CLICK & COLLECT OR QUICK DELIVERY
  • Smooth planed finish
  • Enhanced durability
  • Warm honey brown tones
  • Sustainably sourced
  • From: £5.25 metre
  • £35.96 sq metre +VAT
Explore guide
Improved stalility
Long Lasting Performance
Low maintenance
Natural timber beauty
Sustainably sourced

Helpful guides

Is Thermo Ash Decking worth it for UK gardens?

We look at the benefits, lifespan and appearance of Thermo Ash decking in UK conditions.

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Thermo Spruce Decking vs Thermo Ash Decking

Comparing two popular thermally modified options to help you choose the right decking

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Thermowood Pine Decking vs Standard Softwood Decking

See how Thermowood Pine compares for durability, stability and value for money

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Does Thermo Ash Decking need oiling?

Find out how to care for your decking and whether oiling is necessary to maintain its finish

Read more >
Need help choosing the right decking?

Our friendly team can help you selecy the perfect timber for your project

Talk to an expert

Frequently Asked Questions

What is thermally modified decking?
Thermally modified decking is timber that has been treated using heat and steam to improve its stability and durability for outdoor use. This process reduces the timber’s moisture absorption, helping it perform better in changing weather conditions while still keeping the natural beauty and character of real wood.
What are the main benefits of thermally modified decking?
The main benefits of thermally modified decking include improved dimensional stability, better performance in changing weather, reduced moisture movement and a more refined natural timber finish. It is a strong choice for outdoor spaces where both appearance and long-term performance matter.
Which thermally modified decking option is right for my project?
The right option depends on your budget, design style and the overall finish you want to achieve. Thermo Ash is ideal for premium contemporary spaces, Thermory Spruce suits practical modern gardens and terraces, and Thermowood Pine offers a more cost-effective route into thermally modified decking. Each option has its own strengths, so the best choice will depend on the specific look and performance you need.
Does thermally modified decking need oiling?
Thermally modified decking does not always need oiling, but it depends on the finish you want to maintain. If left untreated, it will naturally weather over time and develop a softer silver-grey tone. If you want to preserve more of the original colour, using a suitable decking oil can help maintain the appearance for longer.
Will thermally modified decking turn grey over time?
Yes, like many natural timber products used outdoors, thermally modified decking can gradually turn grey over time if left untreated. This is a natural weathering process caused by exposure to sunlight and the elements. Many customers like this aged look, while others choose to maintain the original colour with treatment.
Is thermally modified decking suitable for UK gardens?
Yes, thermally modified decking is very well suited to UK gardens. Its improved stability helps it cope better with moisture, temperature changes and general outdoor exposure than untreated timber. This makes it a practical and attractive choice for patios, terraces, garden rooms and other outdoor living spaces in the UK.