Let's go!

It almost goes without saying that Oak is one of the oldest construction materials used in the UK. It has been a staple of tools and homes since medieval times, and was frequently recorded in building accounts from the reign of Henry III (1216 – 1272 AD) onwards. The longevity and durability of Oak are renowned globally, and at EcoChoice we consistently recommend it as a reliable timber for various projects.

But to ensure your Oak is up for the job at hand, it needs to be correctly graded. This is where Oak classifications come into play, and we have put everything you need to know about them (and how they will influence your construction) in this guide.

What Is D30 and D40 Timber?

In structural applications, Oak is classified into specific visual grades, each corresponding to a particular strength class. On the surface, the visual grades for structural oak are:

  • TH1: D40
  • THa: D40
  • TH2: D30
  • THb: D30

However, it is crucial to note that while D40 is technically possible, it is extremely rare and very difficult to source. So, in 99% of cases, D30 is the most practical choice for structural applications, such as beams and structural framing.

For non-structural applications, for example decking and cladding, you will not need a strength-graded timber.

How is the Structural Grading of Timber Determined?

The strength grading of oak usually occurs through visual inspection.This looks at various factors which affect the properties of the timber, including:

  • Grain orientation
  • Slope of grain
  • Knot size
  • Splits and checks
  • Wane (bark along the edges)
  • Distortion (twist, cup, bowing)

After visual grading, timber is usually given either a D30 strength grade or is left ungraded, making its suitability for construction clear. A government-issued UKCA Declaration of Performance will also be supplied.

The Uses of D30 Timber in Construction

D30 Oak timber can be used for heavy-duty construction projects. This includes load-bearing applications, with the high density and strength of graded Oak making it ideal for timber-framed homes and structural beams. It will not need to be treated before use, reducing the need for potentially harmful chemicals and boosting the eco-friendly credentials of your project.

Opting for D30 Oak also allows you to use smaller boards to achieve the structural integrity you need. Do note, though, that these can warp during drying, and need to be kiln-dried carefully and slowly to the required moisture content (between 16-20%, usually).

Non-graded Oak is used for applications which are not load-bearing, such as exterior furniture, cladding and fencing. Despite not being D30 timber, it still offers fantastic durability and is a brilliant choice for a variety of projects.

Sustainably Sourced D30 Oak

Whether you are looking for D30 Oak for structural beams, trusses, or house frames, or just timber boards which are not strength graded, source yours sustainably at EcoChoice. We are committed to sourcing Oak from responsibly managed forests, and we work with independent certifiers such as the FSC and PEFC. This ensures each Oak tree removed is replaced naturally, maintaining biodiversity and ecological balance. By choosing EcoChoice Oak timber, you can help preserve the world’s forests for future generations.

Start an Order of D30 Oak

Ready to order D30 Oak? We can help. Learn more about your options and start an order today by getting in touch with our team.

Tags: , ,

Categories:

D30 and D40 oak

Ask Joe! Expert industry advice

Unsure which timer is best for your project?

Our timber experts have years of experience and will be able to match the perfect species to your project, as well as provide a quote for sustainable timber at highly competitive prices.

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. If we can’t find your request in FSC/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.

Trusted by

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

  • 9 years ago

Excellent service and outstanding product

Cindy Dicks

  • 9 years ago

Great service, quality products and very easy to deal with. Thank you.

Malcolm Coury

  • 6 years ago

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.

Tim Saunders

  • 6 years ago

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

Stone Zone

Your enquiry

Name(Required)

Contact us today

Opening hours

Mondays: 09:00 – 17:00
Tuesdays: 09:00 – 17:00
Wednesdays: 09:00 – 17:00
Thursdays: 09:00 – 17:00
Fridays: 09:00 – 16:00
Saturdays: Closed
Sundays: Closed