Timber brings warmth, character and natural beauty to exterior projects, but exposure to moisture and changing weather conditions means choosing the right timber is important. At The Timber Profile Co., we don't stock or machine timber treated with CCA (Chromated Copper Arsenic). Instead, we offer a range of options for outdoor applications, including MicroPro® H3.2 treated pine, Accoya® modified wood and Western Red Cedar. Each achieves exterior durability in a different way, so the right choice will depend on the application, appearance, performance requirements and budget for your project.
MicroPro® H3.2 treated pine
For applications where preservative-treated timber is required, selected profiles can be produced in MicroPro H3.2 treated pine. MicroPro uses micronized copper azole (MCA) preservative technology to help protect timber against fungal decay and insect attack. Unlike traditional CCA treatment, the MicroPro system does not use arsenic. MicroPro also has independently assessed environmental credentials. Its treatment technology was the first treated wood process to receive Scientific Certification Systems' Environmentally Preferable Product (EPP) certification based on Life-Cycle Assessment. The MicroPro process uses approximately 80% less total energy than the standard wood treatment processes assessed in the study, while also reducing greenhouse gas emissions and copper released into the environment. MicroPro-treated timber has a lighter, more natural appearance than many traditional treated timbers and can be painted or stained. Appropriate coatings, fixings and installation methods should always be selected for the intended application. MicroPro H3.2 may be a good choice when you need: H3.2 treated timber for an appropriate exterior application Protection against fungal decay and insect attack A treated pine option that can be painted or stained An arsenic-free alternative to CCA-treated timber A treatment process with independently assessed environmental credentials
Accoya® modified wood
Accoya takes a different approach to exterior durability. Rather than relying on conventional preservative treatment, the properties of the wood are modified through a process called acetylation. This process reduces the timber's tendency to absorb moisture, significantly improving its dimensional stability and resistance to biological decay. That means less swelling, shrinking and distortion as environmental conditions change. Its stability makes Accoya particularly well suited to precision exterior timber applications, including windows, doors, cladding and detailed profiles. It is also easy to machine using conventional woodworking equipment. Accoya has strong environmental credentials too. It comes from FSC® certified forests, is non-toxic and recyclable, and holds Cradle to Cradle Gold certification. Its extended service life also helps keep carbon stored within the timber for longer and reduces the need for premature replacement. Manufacturer warranties of up to 50 years are available for Accoya, depending on the application and applicable warranty conditions. Accoya may be a good choice when you need: Excellent dimensional stability High durability in demanding exterior conditions Reduced swelling and movement Timber suitable for precision machining Strong sustainability credentials A long service life
Western Red Cedar
For projects where the natural character of the timber is an important part of the finished result, Western Red Cedar offers another option. Sourced from managed forests in North America, Western Red Cedar is lightweight, durable and dimensionally stable. Naturally occurring oils help make the timber resistant to decay, allowing it to be used for appropriate exterior applications without preservative treatment. Cedar is particularly well suited to applications such as exterior joinery, mouldings and weatherboards. It can be painted or stained, or left unfinished where its natural appearance is part of the design. Left to weather naturally, its distinctive reddish tones gradually develop into a soft silver-grey. Its dimensional stability also helps it resist excessive shrinking and cracking as conditions change.
Western Red Cedar may be a good choice when you want: Naturally durable timber An option that doesn't require preservative treatment Visible grain and natural timber character The choice to paint, stain or allow the timber to weather naturally A lightweight, dimensionally stable timber A premium natural finish Which outdoor timber is right for your project? There isn't one timber option that's right for every outdoor application. MicroPro H3.2 treated pine offers a practical preservative-treated option where H3.2 timber is appropriate. Accoya offers exceptional stability and durability where long-term performance and reduced timber movement are priorities.
Western Red Cedar combines natural durability with distinctive grain and character, making it particularly appealing where the timber itself forms part of the finished aesthetic.
Your choice should take into account where the timber will be used, its exposure to the elements, the profile being produced, desired appearance, coating system and any project-specific requirements.
If you're not sure which timber is right for your application, talk to our team. We can help you work through the options and find a solution that suits your project.
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Choosing timber for outdoor applications
