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When choosing timber for your construction project, one of the key considerations is the presence of knots in the wood. But are they something to avoid or something to embrace? To help grow your timber knowledge and work out the right boards for your project, we have taken a look at the pros and cons of timber knots, compiling everything you need to know in one place.

What Are Timber Knots?

Timber knots are natural irregularities in the wood, usually forming at sites where branches once grew on the tree. Live knots are tougher, less problematic knots, formed from branches which were still attached to the tree when it was felled. Dead knots on the other hand, which form when branches fall off pre-felling, can cause more problems. It is also the case that some are caused by damage to the timber, including injuries while the tree was growing or fungal infestations. Because they cause deviations in the grain of timber, they’re considered a point of structural weakness, so bear this in mind if your timber is required to span over any distance and support any weight.

As circular or oval-shaped features, knots appear as darker, denser areas within the wood, contrasting with the surrounding grain pattern and causing changes in the colour. But the size and frequency of knots in your timber products can vary, making them more or less suitable for your project, depending on what you require.

What Are Pitch Pockets?

Pitch pockets are similar to knots in your timber but are not  actually the same thing. They begin with either insect damage or a large impact to the tree, creating an area of damage which takes the form of a hole. The sap from the tree then fills this hole, leading to a resin-filled pocket. It is important to note that pitch pockets can make your timber weaker and leak sap, so they are not ideal for all construction applications.

The Advantages of Timber Knots

The main appeal of knots is that they add a unique and charming look to timber, bringing plenty of visual appeal to your project. They tell a story of the tree’s growth, with each knot marking a branch which once sprouted. Some woodworkers and enthusiasts appreciate the rustic, natural look which knots provide. No two knots are alike, and embracing these differences in your wood means embracing their unique aesthetic.

It is also good to note that knots often make timber more affordable, which is a definite perk when you are on a budget!

Are Knots in Timber Bad?

Knots are not an out-and-out bad characteristic in your timber, but they do come with some disadvantages with which it is important you get to grips before choosing your boards.

The main downfall of knots is that they weaken the wood, especially when they are overly prevalent. If you find boards with large clusters of knots or a few big knots which take up a lot of space on the board, you might find the timber will not do as well in load-bearing situations. For projects which need structural integrity, it is best to keep knots to a minimum. There are visual grading rules that can help you decide what boards are suitable, or you can also ask your supplier for strength graded timber such as C24 or D30.

Working with wood which contains knots can also be more challenging, which is important to consider if you are a beginner. Knots can dull cutting tools and pose difficulties when trying to achieve smooth surfaces or precise cuts.

Over time, a crucial issue posed by a lot of knots is that they can loosen, creating gaps in your wood or even (in rarer cases) falling out. Not ideal!

Making the Right Choice

So, how do you decide whether knots in timber are a good or bad thing for your project? Here are some tips:

  • Consider the application: for structural or load-bearing applications, such as decking, it is generally best to minimise knots or use strength graded wood, with fewer and smaller knots to ensure strength and safety.
  • Look at the size and quantity of knots: small, tight knots are less likely to cause structural issues than large, loose ones.
  • Embrace the look: if you appreciate the character of knots and do not need to worry about structural integrity, then there is no need to shy away from them!

In some cases, you can strategically incorporate knots into your design, balancing them with sections of clear wood to achieve both strength and visual appeal. For non-structural applications such as cladding, a rustic look with lots of knots can sometimes be the perfect look.

Find the Right Timber Boards at EcoChoice

Whether you are sold on the aesthetic appeal of timber knots, or you are looking for boards completely clear of them for wood which is structurally sound, we can help. At EcoChoice, we supply FSC-certified timber for projects across the UK and are more than happy to help you find the right species. Get in touch with us today and let’s talk timber!

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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.

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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

  • 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

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

Emma Hurrell

  • 1 month ago

Good quality, great service, fast delivery!

Marinella Li

  • 9 years ago

Experts in Timber, Nationwide delivery

Joe Middleton

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