Treated vs Untreated Timber: A Comprehensive Guide

September 20, 2024

Whether you’re constructing decking, building furniture, or framing a house, choosing the right timber for the job is crucial. Understanding the differences can not only affect the durability and safety of your structure but also influence your budget and environmental footprint. There are some key distinctions between treated and untreated timber so let’s take a look and help you make an informed choice for your next project.

What is Treated Timber?

Treated Timber is wood infused with chemicals to protect it from natural decay, fungi, insects, and other environmental factors that cause deterioration. The treatment process typically involves pressure-treating the wood to ensure the chemicals penetrate deeply into the fibres. This process makes treated timber highly resistant to rot, termites and moisture damage. Whilst some processes can be damaging to the environment, at PGR Timber we supply wood treated with less harmful chemicals to reduce the impact on the environment.

• Common Uses: Treated timber is ideal for outdoor projects such as fences, decking, landscaping structures and any application where the wood will be exposed to moisture or insects.

What is Untreated Timber?

Untreated Timber, on the other hand, is wood without any chemical preservation process. It’s in its natural state and does not have the enhanced resistance to environmental factors that treated timber offers. While untreated wood can still be durable in the right conditions, it’s more vulnerable to decay, insect infestations and moisture-related issues like warping and rotting.

• Common Uses: Untreated timber is often used for indoor projects such as furniture, cabinetry, flooring, or framing within homes where the wood is not exposed to harsh elements.

Durability

• Treated Timber: The treatment process significantly extends the lifespan of the wood, especially when exposed to harsh environmental conditions. Treated timber can last for decades outdoors, making it the preferred choice for long-lasting outdoor structures.

• Untreated Timber: While still strong, untreated timber is far more susceptible to environmental factors. Without protection, untreated wood can rot, warp, or attract pests, reducing its longevity in outdoor applications.

Cost

• Treated Timber: The chemical treatments and the pressure-treating process add to the cost of treated timber. However, the initial higher investment is worth it for many projects due to the extended lifespan and reduced maintenance costs.

• Untreated Timber: Typically cheaper upfront, untreated wood is more budget-friendly in the short term. However, it may require more frequent repairs or replacements if used in inappropriate conditions, which could increase costs over time.

Environmental Impact

• Treated Timber: While the chemical treatment helps the wood resist decay, it also raises environmental concerns. Some treatments, such as chromated copper arsenate (CCA), contain chemicals that can be harmful to the environment. However, modern-treated timber often uses less toxic alternatives, such as alkaline copper quaternary (ACQ). At PGR, our green-treated timber has the Tanalith E treatment and our yellow battens have the low-pressure Vacsol treatment (a water-based preservative containing biodegradable fungicides) – both of which are a safer and more modern version of the treatment.

• Untreated Timber: Since it contains no chemicals, untreated timber is generally more environmentally friendly. If sustainably sourced, untreated wood can have a low environmental impact, especially if it’s harvested from responsibly managed forests.

Safety

• Treated Timber: The chemicals in treated wood can pose health risks if not handled properly. It’s important to wear protective gear, such as gloves and a mask when cutting or sanding treated timber, as inhaling dust or handling the wood without protection can be harmful.

• Untreated Timber: Since there are no chemical additives, untreated timber is generally safer to handle. This makes it a preferred choice for furniture and other indoor projects, particularly for those sensitive to chemicals.

Aesthetic Appeal

• Treated Timber: The treatment process can slightly alter the appearance of wood, giving it a greenish or brown tint depending on the chemicals used. While this can be stained or painted over, it’s worth considering if natural beauty is a priority.

• Untreated Timber: Many people prefer the natural look of untreated timber, which showcases the wood's organic colour and grain. It’s easier to work with in terms of staining or finishing, making it ideal for projects where aesthetics are key.

Maintenance

• Treated Timber: Treated timber requires less maintenance over time, particularly for outdoor applications. Regular cleaning and occasional sealing can help it maintain its integrity, but overall, it’s much lower maintenance compared to untreated wood in outdoor settings.

• Untreated Timber: To extend its lifespan, untreated timber used outdoors will need to be regularly sealed, painted, or stained. Additionally, you’ll need to be vigilant about moisture exposure and pest control.

What We Offer

We offer a wide range of timber and sheet materials, including MDF sheets, plywood sheets, timber cladding, sawn timber, treated timber and more. Our selection is designed to meet the needs of various construction and DIY projects. All our timber products are sustainably sourced and have certifications from PEFC™ and FSC® standards. This ensures that our timber is responsibly harvested and meets high environmental and ethical standards.

Want to find out more about timber decking specifically? Check out our dedicated blog, here: Timber Decking Unleashing The Natural Beauty of Outdoor Living and our Timber Decking page. Check it out here:

The decision between treated and untreated timber depends largely on the nature of your project. If you’re building something that will face the elements, such as a deck or fence, treated timber is the clear winner for its durability and low maintenance needs.

For indoor projects where aesthetics and chemical exposure are concerns, untreated timber is a better option.

Always consider the long-term costs, environmental impact and specific requirements of your project before making a final decision. Each type of timber has its strengths and weaknesses and choosing the right one can help ensure the success and longevity of your woodworking endeavour.