Timber cladding considerations
The UK timber cladding market is growing, providing numerous sales opportunities for merchants and contractors alike. Here Bernie Roberts, National Product Manager for Cladding Solutions at International Timber, examines cladding options and trends, before advising how to correctly specify and install timber cladding.
The timber cladding market in the UK is poised to grow at a CAGR of 4% by 2027, with growing demand in both residential and non-residential construction driving market growth[1]. Ever since the start of the COVID-19 pandemic, the demand from homeowners to refurbish properties has increased, and timber is the go-to product due to its cost-effectiveness, durability and sustainability.
What is cladding?
Cladding is the application of one material over another to provide a skin or layer. In construction, cladding is used to provide a degree of thermal insulation and weather resistance, and to improve the appearance of buildings. Cladding can be made in a wide range of materials including wood, metal, brick, vinyl, and composite materials.
Rainscreen cladding – also known as splayed or rhombus cladding – is a form of weather cladding designed to protect against the elements, but also offers thermal insulation. The cladding does not itself need to be waterproof, merely a control element; it may serve only to direct water or wind safely away in order to control run-off and prevent its infiltration into the building structure.
Cladding may also be a control element for noise, either entering or escaping. It’s also important to remember that cladding can become a fire risk either by design or material. Merchants should remind their customers to double check that the cladding they install is correctly designed to provide adequate drainage and ventilation, as well as being fire retardant.
Why use timber cladding?
Given the importance of EPDs, it’s not surprising to find that people are keen to work with sustainable products. In fact, there has been a growing realisation in the need to use more natural and low carbon building materials such as timber in recent years, and increasingly builders and contractors are adopting this line of thinking.
Timber cladding also offers many years of visually pleasing aesthetics if fitted correctly and maintained effectively. Timber is unique and each piece is different, it can quickly and easily be rejuvenated to alter its appearance.
As well as being economically priced and extremely durable, timber cladding also offers increased thermal insulation over other building materials. 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 product.
What are current timber cladding trends?
Connecting the built environment to nature with the use of biophilic design is a huge trend now. Introducing a biophilic aesthetic on the external facade of a building using timber cladding helps to blur the line between the indoors and outdoors, achieving a more organic flow between building and nature.
Accoya® wood is fast becoming the material of choice for exterior cladding applications. The enhanced durability of Accoya® facilitates a lifespan of at least 50 years above ground and 25 years in-ground, improving carbon sequestration potential and lowering lifetime material consumption versus other materials.
Fully finished claddings are also much sought-after now. International Timber offers fully factory finished timber cladding and we also offer the technical back up to advise on the best products to use for each project as well as being able to advise on the installation and maintenance of the cladding, which is often overlooked.
What should we be advising customers?
Timber species, profile and additional coating options are all things to consider. Softwood, hardwood and modified timbers all play a part in the design stage, and we recommend a 10% wastage allowance on all cladding timbers and up to 15% on Thermowood, due to the brittle nature of the product.
Once a profile has been chosen, the timber chosen should be durable enough to meet the service life required. Where the natural durability of the timber species is not good enough, a wood preservative, factory impregnation or a modified timber should be considered.
Many timbers can be left uncoated to weather naturally to a silver-grey colour over time, but elevation should be considered. A northern elevation will not get as much exposure to the elements as a south facing elevation, whilst a southern elevation will require more maintenance if the cladding is coated.
What about coatings and fixings?
Coatings offer both water repellence and UV protection. The darker the colour, the more pigment and the more the 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. This is because timber is hydroscopic and will take in and expel moisture as the humidity around the timber increases or decreases.
We suggest that if any profile is to be coated, the leading edges have a slight round on them to aid with coating adhesion. Similarly, it is recommended that timber requiring fire treatment is done in controlled conditions and by an approved factory application. The use of site brush or spray applied fire treatments are not approved by the Wood Protection Association (WPA).
Finally, it is recommended that fixings are specified to be made of a non-corrosive material such as stainless steel, which are 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 merchants and contractors face in working to help build safe, 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.
For more information, visit www.internationaltimber.com or email [email protected].
