Types of Wood Cladding Explained

Before we get to wood cladding, for those who don’t work in the construction industry, let’s look at what cladding is first. 

Cladding is “the application of one material over another to provide a skin or layer… to provide a degree of thermal insulation and weather resistance, and to improve the appearance of buildings.” 

Of course, at the moment in the UK, the word ‘cladding’ in the construction industry is a real watchword. After the Grenfell Tower disaster in North Kensington in June 2017 fire safety in tall buildings has been looked at closely, “The 24-storey block was clad in aluminium composite material or ACM which is now known to be dangerously combustible.” 

Using wood as a cladding material offers many advantages and woods such as OrganoWood not only last a long time, weather to a pleasant grey tone, but are also resistant to fire

Now that we have identified what cladding is let’s move on to the different types of wood cladding. Some types of timber are more durable than others. 

There are five different durability classes. The durability rating is based on the heartwood only. Heartwood is the central part of trees. It is mechanically strong, resistant to decay, and less easily penetrated by wood-preservative chemicals than other types of wood

Natural Durability Class

BS EN 350: 2016

Desired services life/years

Occasionally wet (with coating)

Desired service life/years

Frequently wet

1 – Very Durable >60 60
2 – Durable 60 30
3 – Moderately Durable 30 15
4 – Slightly Durable 15 <15
5 – Not Durable <15 <15


The rows highlighted in yellow will all need to be appropriately treated to extend their service life. 

Principal softwood species used in the UK for cladding

Common name

Natural Durability

Class (BSEN350: 2016)

Sapwood Treatability Movement Density kg/m³ Availability
Douglas Fir          
Home grown 3 – 4 Resistant Small 470 – 520 Specialist supplier
North American 3 Resistant Small 510 – 550  
European 3 – 4 Resistant Small 470 – 650 Specialist supplier
Hybrid (aka Dunkeld) 3 – 4 n/a n/a n/a Specialist supplier
Japanese 3 – 4 Resistant Small 520 Specialist supplier
Siberian 3 – 4 Resistant Small or medium 680 – 700 Good
Scots Pine / European redwood 3 – 4 Permeable Medium 500 – 540 Good
Lodgepole Pine 3 – 4 Permeable Small 430 – 470 Good
Radiata Pine 4 – 5 Permeable Medium 420 – 500 Specialist supplier
Southern Yellow Pine 4 Permeable Medium 650 – 670 Specialist supplier
Sitka Spruce / European Whitewood 4 – 5 Resistant Small or medium 400 – 450 Good
Norway Spruce 4 Resistant Medium 440 – 470 Good
Western Red Cedar          
Home grown 3 Resistant Small 330 – 390 Specialist supplier
Canadian 2 Resistant Small 330 – 390 Specialist supplier


It is also possible to enhance the performance (durability and stability) of most of the types of timber listed above, through either chemical, biological, or heat processes. 

The primary objective in modifying wood is to make them more durable (less prone to rot). This makes modified woods last longer than unmodified woods. The most commonly modified timbers for cladding in the UK are depicted below. Thermowood® mnetioned below is the registered process controlled by the Finnish Thermowood Association – we sell this and also other types of thermo modified timbers

Modification process / brand Base species Assigned Natural Durability Class Dimensional stability / movement Strength Coating performance
Thermally modified timber          
Thermowood S² (190°C) Pine or Spruce 3 Improved + Unchanged Improved
Thermowood S² (185°C) Birch or Aspen 3 Improved ++ Reduced Improved
Thermowood D (212°C) Pine or Spruce 2 Improved + TBC Improved
Thermowood D (200°C) Birch or Aspen 2 Improved ++ Reduced Improved
Thermodified Frake Black Afara   Improved ++ TBC Improved
OrganoWood Pine or Spruce 2 Improved ++ Unchanged TBC
TMT Ash / ThermoAsh American Ash 1 TBC Unchanged Improved
Chemically modified timber          
Accoya (510kg/m3) Radiata Pine 1 Improved ++ Unchanged Improved


There are also hardwood species such as Oak, Iroko and Cumaru that are suitable for cladding, although due to their usually higher density and strength, special attention is needed when fixing them.

Cladding also makes a building more aesthetically appealing as we stated earlier. The tradition of using cladding to enhance the appearance of a building goes back a long way and is still universally appealing. 

In Ancient Japan the charring tradition of Shou-Sugi-Ban was used for centuries to make their buildings resistant to fire, rot, insects and UV effects from the sun. The practice started in the 18th century. Buildings clad in Shou-Sugi-Ban treated cladding can be protected for up to 120 years. We have now added charred Larch to our range of cladding – with a wide choice of charring levels.

And because timber is a natural product, using wood cladding means that you are protecting your home as well as the planet. In this year of #WoodCO2tsLess, doing anything you can to help reduce the world’s CO2 emissions is an incredible step in the battle to fight climate change. 

EcoChoice are dedicated to fighting global warming and to encouraging people to switch to using independently certified sustainable wood for their construction and design work. 

Speak to us on 0345 638 1340 to find out how we can provide you with the exact sustainably sourced materials you need for your next project. 

Let’s work together to tackle climate change #WoodCO2tsLess.


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