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When it comes to civil and landscaping projects, choosing the right timber species is about more than cost and aesthetics. Your timber needs to be durable and long-lasting, with excellent resistance to moisture and insects – not to mention being able to withstand the Great British weather. An increasingly popular solution is to opt for impregnated softwood.

Simplify your search for the right timber by getting to grips with what treated softwood is, and the right Use Class for your project.

What is Impregnanted Softwood?

In the UK, softwood timber species (e.g. Pine, Larch, Spruce or Douglas Fir) are widely available and a cost-effective choice, but do not often meet the durability standards required for civil and landscaping projects. This is where timber impregnation comes in.

Impregnated softwood means the timber has been treated with a chemical preservative to increase its durability. Unlike surface finishes, this treatment is pumped deep into the fibres of the timber, going beyond the surface of the wood to penetrate the entire board.

After impregnation, these species gain an envelope of exceptional resistance to rot, fungi and insect attack, making them fit for purpose. But before diving in and choosing an impregnated softwood, it pays to know a bit more about the Use Class of your timber.

What Are Use Classes?

Use Classes are used across Europe as a way to classify timber, ranging from Use Class 1 to Use Class 5. Each classification denotes the different applications for which the timber is suitable, helping architects, construction professionals and DIY enthusiasts choose the right species or treatment level for their project.

If you work in civil engineering or landscaping, the main classes you will need to pay attention to are 3, 4, and 5.

Use Class 3 Impregnated Softwood

If your impregnated timber is treated to Use Class 3 (UC3), this means that it is designed for outdoor applications where the timber is exposed to the elements, but kept away from the ground or long-term contact with water. Some common applications of UC3 timber include:

While UC3 timber will not fare well if it is constantly wet, it can handle rain and high humidity, making it well-suited for outdoor life in the UK.

Use Class 4 Impregnated Softwood

If your construction is more exposed to water or is going to be in direct contact with the ground, you should look for a Use Class 4 (UC4) impregnated timber. This is more durable than UC3, with a higher resistance to rot, making it perfect for:

UC4 treatment offers deeper preservative penetration and far greater durability, helping protect your construction against rot.

Use Class 5 Impregnated Softwood

Softwood, which has been treated to a Use Class 5 (UC5) classification, offers excellent properties for heavy-duty civil and landscaping projects. Typically, this is used in cases where the timber will be either frequently or constantly exposed to water, including:

Even when continuously saturated with either fresh water or seawater, UC5 impregnated softwood will bring longevity to your construction project. It is also resistant to marine borers, which is essential for timber used in marine construction.

Buy Impregnated Softwood at EcoChoice

At EcoCHoice, we supply FSC® or PEFC-certified impregnated softwood for construction projects around the UK. Whether you are taking on a domestic, commercial or public project, we can help you find the best softwood timber for the job.

To learn more or start an order, reach out to us today.

treated softwood timber

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Frequently asked questions

Do you supply timber for domestic uses?

Yes, we supply timber for domestic applications as well as commercial and public constructions. From garden decking to shed cladding, we will be happy to supply smaller deliveries for home use.

Is your timber FSC®-certified?

Yes, all timber we supply is FSC or PEFC certified and sourced from independently verified responsibly managed forests and other controlled sources. If we can’t find your request in FSC or PEFC certified timber we’ll suggest an alternative that is certified or clearly note that the offer is minimum EUTR.

Where does EcoChoice deliver to?

EcoChoice delivers to construction sites, warehouses and homes across the UK, as long as there’s access and unloading for our trucks.

What are the best timber species for exterior use?

There are many different timber species suitable for exterior use and which is the best for your project depends on your requirements. In general, though, we recommend EkkiGreenheartOpepe and Oak for heavier civil/marine uses. For intermediary external use such as decking, where the timber needs to be both strong and durable but not on the same level as civil engineering (bridgespiling, etc) we usually supply CumaruIpe, Jatoba, and Balau. And for the lighter exterior use where the timber is non-structural such as cladding, we deliver CedarLarchThermowood and others.

Which timber is the most durable?

Durability Class 1 timbers are the most durable. This of course depends on the use (hazard) class they’ll be in service for. For direct ground and water contact such as sleepers, fenders, marine piling, etc, Ekki and Greenheart are known to be the most durable timbers available. For decking and cladding where there’s no direct ground contact (use class 3) there’s a much wider range of timbers such Larch, Cedar, Thermo modified Pine or Ash and others.

What’s the best timber for internal cladding?

Internal cladding, where your timber is not in ground and not exposed to the elements can be classed as either use-class 1 or 2 – in which case most timbers will meet this durability criteria. That is not to say they’ll be the best, since internal environments have lower humidity (moisture) levels than outside. So in these cases, it’s best to go for a kiln-dried timber cladding board as these are more stable and delivered already in lower MC (moisture content) than the usual fresh sawn timbers sent to external applications. A word of caution – as timber reacts to variations in moisture, it’s best to avoid cladding any areas inside your bathroom.

How can I make decking less slippery?

The first thing is to ensure your deck boards are kept clean from leaves and other debris which will, over time, cover the surface and make it more slippery. Grooved boards can be used to improve grip if installed and used perpendicular to traffic, so especially useful in narrow passages and footbridges. Lastly, you can add our Grip-Choice strips: these are a mix of epoxy with aggregates that add gripping ridges to your deck area. Gripchoice is an easy way to make decking less slippery and safer, especially over large areas or where there’s high traffic. We can pre-install Grip-Choice strips for your decking before delivery or ship the strips separately to add to your existing deck’s grooves as a retro-fit solution.

What wood machining services do you offer?

We can offer planing, sawing, drilling and profiling of rough-sawn wood to any profile you require: from handrails to large port fenders.

Can you supply pre-drilled timber?

Yes, we will be happy to provide pre-drilled timber which is tailored to your needs for quick installation, thus saving you valuable time on site.

What cladding profiles do you supply?

We provide a wide range of cladding profiles, including tongue and groove, featheredge and shiplap. You can check the standard profiles here – but we can also match or custom make profiles to suit your specific needs.

Does timber change colour?

Yes, timber is well-known for changing colour over time. Some species can darken quickly right after installation, and like most untreated wood will eventually weather to a beautiful silver-grey. Interior timber is less likely to change colour (depending on conditions), and timber can be stained, painted or treated with UV-resistant oils to reduce colour change.

Do I need to treat exterior timber?

Some timbers such as Oak and Ekki, can withstand the strains of exterior use without any treatment. However, to extend the lifespan and maintain the aesthetic of your wood, we do recommend treating your timber with stains and oils. Pre-treated timber, such as ThermoWood and OrganoWood, are low-maintenance options which are more durable, but can have their life service extended by applying a clean and stain maintenance schedule.

Do I need to treat interior timber?

Depends on what area the timber is being used. For floor joists and timber rafters, it is common to see timber treated, or least very well kiln-dried. Other uses such as flooring may benefit from varnishing while internal timber cladding for decorative purposes shouldn’t require any treatment other than if you want to change its colour with different types of stains or oils.

Where are you based?

We’re based in Cambridge, UK, and coordinate multiple sawmills all over the world to manufacture your order. We then organise delivery with a range of hauliers so that your orders gets to your site on time.

What are the usual decking sizes?

Timber decking is usually 21x140mm or similar. For heavier applications where there’s more load and traffic, we deliver 35 or 45mm thick boards (such as Hastings Pier). Narrower boards are also possible: 95-90mm is a standard width – but we can manufacture whatever size you require.

What are the usual cladding sizes?

Typical cladding section sizes are 18×95 and 18x145mm although we can always custom make a section to suit your project’s design requirements. That includes waney edge boards in Oak or Chestnut as well as extra wide 195mm boards.

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What our customers say about us

Good quality, great service, fast delivery!

5

Marinella Li

Always helpful! One of our valued TDCA DeckMark and CladMark accredited supplier members which means their quality procedures are routinely audited and stand up to scrutiny giving you extra peace of mind.

5

Janet Sycamore

Having needed the supply of cladding, decking boards and other specified timbers through out the year Eco choice have been very helpful in sourcing the specified timbers and quantities required at a very competitive price.

5

Tim Saunders

Great quality, service and price. A pleasure to deal with. I would highly recommend Eco Choice.

5

Emma Hurrell

Fantastic company- Mike and the team are the best in the business- worked with them for many years.

5

Prem Raja

Always reliable and quality products, easy to deal with company.

5

Stone Zone

4.9

Average rating on Google Reviews

  • 1 month ago

Good quality, great service, fast delivery!

Marinella Li

  • 6 years ago

Great quality, service and price. A pleasure to deal with. I would highly recommend Eco Choice.

Emma Hurrell

  • 9 years ago

Experts in Timber, Nationwide delivery

Joe Middleton

  • 3 years ago

Always helpful! One of our valued TDCA DeckMark and CladMark accredited supplier members which means their quality procedures are routinely audited and stand up to scrutiny giving you extra peace of mind.

Janet Sycamore

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