How to correctly specify and install timber cladding

How to correctly specify and install timber cladding

Kerry Wardle, Head of Marketing at International Timber, explores cladding options and trends, with advice on how to correctly specify and install timber cladding. 

Exterior cladding in the residential and non-residential sectors is expected to have significant growth in the next forecast period due to its insulation and aesthetic benefits.

The UK timber cladding market is set to experience a growth rate of over 4% during the next five years, due to its cost-effectiveness, durability, and sustainability. Timber provides many benefits to surpass other building materials, which is why many builders are opting to use timber cladding in their projects. 

What is cladding?  

Cladding is the application of one material over another to provide a skin-like layer. The cladding layer is used to provide thermal insulation and protect the structure from weather-related damage. The exterior skin shields walls from moisture and penetrations caused by other weather-related damage, while dramatically changing the appearance of a building, potentially increasing its value.  

What are the current timber cladding trends?  

Accoya wood is increasingly becoming the material of choice for its durable qualities, resistance to rot and insect damage, and a life span of 40 to 60 years. The timber’s natural warm appearance used on the external facade of buildings helps to bridge the gap between indoors and outdoors, achieving a more organic flow between the building and nature.  

Thermally modified timbers such as Redwood Thermowood and Radiata Pine Thermowood are also seeing an upward trend, partially due to the lack of Siberian Larch, but also due to the fact that these timbers offer increased durability even when exposed to the most extreme environments.   

Benefits of cladding?  

As well as its durable and resistant qualities, timber cladding also offers increased thermal insulation over other building materials, contributing towards a more sustainable construction industry. Wood is a natural insulator, and when used in cladding form can help to reduce a building’s heat loss, increasing energy efficiency by lowering heating and cooling bills.

The timber used for exterior cladding requires less energy to produce than any other construction material, contributing to sustainability efforts in the supply chain. Timber’s long life allows for reuse or recycling at the end of its life. Its unique design facilitates easy rejuvenation to change its appearance, providing builders with a long-term solution for builders.  

Timber cladding also effectively reduces noise pollution by converting sound waves into heat. This makes it a more effective sound-dampening material compared to other cladding options.  

Things to consider  

Timber species, profile and additional coating options are all things to consider, as well as location of the cladding, i.e. in exposed or coastal applications. When costing up a project, we recommend a 10% wastage allowance on all cladding timbers and up to 15% on Thermowood, due to the brittle nature of the product. 

Additionally, it is essential that the timber cladding is stored correctly on-site to protect it from the natural elements. Storage areas should be dry and well-ventilated, not subject to extreme temperatures. Sudden changes in moisture and temperature can cause swelling or shrinkage of components.  

What about coatings and fixings?  

It is crucial to use wood protectants and cleaning products regularly to preserve the appearance of long-lasting cladding. The performance and lifespan of lower durability woods and cheaper timber species can be improved by using factory-applied treatment technologies such as preservative treatments or wood modification. 

Wood coating offers both water repellence and UV protection. The darker the colour, the more pigment and the more protection against UV degradation, whereas clear coatings offer very little protection. 

All coated cladding requires end-grain and fixings to be sealed to ensure no moisture ingress. We suggest that if any profile is to be coated, the leading edges have a slight round on them to aid with coating adhesion. 

Timber is easily worked, and the fire performance of timber can be improved by factory-approved treatments such as impregnating the raw timber with suitable fire-retardant products. 

It is recommended that timber requiring fire treatment is done in controlled conditions and by an approved factory application. The use of site brushes or spray-applied fire treatments is not approved by the Wood Protection Association (WPA). 

Additionally, fixings should be specified to be made of non-corrosive material such as stainless steel, which is ideal for all timber species. Other materials can cause permanent black spotting and corrosion staining to the surface of the cladding.  

Here at International Timber, we recognise the challenges builders and contractors face in working to create safe, and sustainable buildings. Offering a vast array of species and finished products, our specialist teams provide customers with total solutions all managed to precise individual requirements. 

International Timber provides factory-finished timber cladding that enhances the appearance of buildings, while also providing expert knowledge on the appropriate wood design, treatments and storage solutions for each build.

For more information on International Timber visit

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