Modified timber joinery for exteriors: how thermal treatments enhance performance in harsh conditions

Timber is well-known for its versatility, strength and unmatched natural beauty. As an exterior construction material for joinery, you cannot make a better choice! Modified timber cladding, for example, can withstand harsh weather conditions. But when exposed to harsh weather and fluctuating temperatures, some timber species can wear a little more visibly than others, which is where thermal modification comes into play.

From decking to cladding, get to grips with how modified timber joinery could be your best bet for exterior builds. Consider how modified timber, especially when used in cladding, can enhance both durability and style.

What is Thermally Modified Timber?

Thermal modification is a chemical-free preservative process used on timber products. During modification, your timber is heated to temperatures typically between 160°C and 230°C in a controlled, oxygen-free environment, where the wood is also subjected to high pressure. This actively alters the timber’s cellular structure, reducing its water absorption and changing its composition to boost durability. Modified timber cladding emerges as a clear solution when aiming for durability and longevity.

While extremely durable timbers, such as Ekki and Greenheart, will not need thermal modification, it can be great if you want to use a less dense timber, for example Pine, Ash or Spruce, especially as non-structural cladding. Modified cladding can really elevate the performance of these species.

Why Use Thermally Modified Wood for Exterior Joinery?

A huge perk of using thermally modified timber (or ThermoWood) for exterior joinery is its enhanced dimensional stability. As the treatment significantly reduces the timber’s ability to absorb and release moisture, it makes it less likely that your timber cladding will experience swelling and warping. In joinery, where tight tolerances and snug fits are crucial, this level of dimensional stability is a must to stop gaps and splits from appearing in your structures.

Thermal modification also gently increases its resistance to decay. By burning the sugars that attract fungi and rot, thermo woods end up being likely to last equal or longer than the original wood. Timber modified for cladding ensures prolonged effectiveness against decay.

Your decking and cladding will also be less prone to surface checking and splitting, even under extreme weather conditions. This is handy as the UK’s weather becomes slightly more erratic. When it comes to incorporating modified timber cladding, its ability to withstand such conditions is invaluable.

A Sustainable Timber Treatment

At EcoChoice, we are all about keeping the use of timber in construction as sustainable as possible. It is no surprise, then, that we love using thermal modification as a treatment for external joinery. It is a much greener option than some chemical-reliant preservatives, which are not so great for our natural landscape.

You can also use thermal modification to enhance fast-growing timber species, such as Birch, reducing pressure on slower-growing hardwoods. These species replenish far more quickly, supporting responsible and sustainable forest management. Now that is music to our ears. Enhanced timber through modification supports sustainability and growth.

What to Know Before Using Thermally Modified Wood

While thermally modified timber offers a heap of performance advantages, it can be more brittle than untreated timber. This does not have to be a huge issue, as long as you can make slight adjustments to your joinery techniques. For example, it can be smart to avoid direct screwing, which can cause your timber to splinter and opt instead for pre-drilling. When working with modified timber cladding, planning these adjustments can ensure it achieves its maximum potential.

Find Thermally Modified Timber at EcoChoice

Won over by the many benefits of thermally modified timber for your external joinery? Jump on the EcoChoice bandwagon! We are big fans of this tough, durable timber, and supply it to eco-friendly exterior construction projects around the UK, including both domestic and commercial sites.

To start your order of thermally modified timber, reach out to us today.