Answers to some of the most common questions around timber cladding.
Basics
The essential need-to-knows of timber cladding – covering definitions, species and profiles.
Cladding is a non-structural wall covering (or facade) for the exterior or interior of a building.
It can give weather protection, insulation and aesthetic appeal. External cladding acts like a 'skin', covering the structural framework of a building.
It can be made from a range of materials, most popularly timber, which is machined to a range of profiles.
Cladding is typically designed in a consistent shape and style, with its appearance varying greatly depending on the material used.
Popular timber species include western red cedar, which boasts a classic reddish-brown and salmon pink colour, as well as Thermo-ayous, which has clear-grade mid-to-dark-brown tones. However, factory-applied coatings can give the timber any colour, from ‘charred look’ black to blue.
The profile that the timber cladding boards are machined to also impact appearance. Featheredge gives a classic rural-inspired feel, whilst shadow gap has a sharper, refined look with gaps between the installed boards creating clear lines.
Shiplap is a timber cladding profile. It has a tongue-and-groove fit — a protruding tongue on the top side and a groove on the opposite side, allowing boards to fit together to create an interlocking fit.
Shiplap boards have a flat, smooth planed surface with a slightly inward curved shape towards the upper part of the board (also known as the ‘scallop’).
When being installed, it is fixed to timber battens with stainless steel screws or nails at 500mm centres. It can be nailed or screwed through the face, or hidden through the tongue if a secret nail profile has been specified.
Read more: Shiplap vs featheredge cladding
Rainscreen cladding, also known as ‘splayed’, ‘rhombus’ or ‘open jointed’ cladding, is made up of boards that are cut at an angle to provide a chamfered edge on each side, producing a parallelogram shape.
It can be fixed horizontally or vertically, typically with a 5mm or 10mm gap to allow for an architectural shadow line to be created. It is face fixed with stainless steel screws to timber counter battens.
Rainscreen cladding is so-called because the profile’s shape encourages water runoff – the installed boards create an overlap.
Unlike most other types of cladding, rainscreen cladding boards are not interlocked or connected. As a result, it should only be applied to a structure that is fully waterproofed.
Read more: Guide to timber rainscreen cladding
Composite cladding is a semi-synthetic product that is a mix of wood and plastic. During manufacture, these elements are blended together, usually through extrusion or compression moulding, with colour tints and additives included to alter appearance and durability.
The percentages of wood-plastic differs from product to product, but most quality composite cladding products have a mixture of 60% wood fibres and 40% recycled plastics, such as high-density polyethylene (HDPE), polypropylene (PP) and polyvinyl chloride (PVC).
As a rule, composite cladding is more expensive upfront – there are more stages involved with its manufacture. However, you may recoup some of these costs by avoiding the need for treatment and maintenance.
Yes, you can paint metal, composite and timber cladding. This includes cedar and larch, which can also be treated with a wood stain or UV oil.
A more high-performance and aesthetically-pleasing option may be to choose a factory coating, where the colour is professionally altered during the product manufacture.
Read more:
Yes, timber cladding has thermal insulating properties.
Wood has tiny air pockets in its matrix-like cellular structure that trap heat and act as a buffer against drastic swings in temperature. This means it resists the transfer of heat, taking on less heat during summer and minimising heat loss during winter.
By acting as a sound-absorbing barrier, cladding also offers limited acoustic insulation properties.
Read more: How sustainable is timber cladding as a building material?
The standard thickness for timber cladding is 20mm.
For some unique profiles like loglap, this can range up to 40mm.
Costs and specification
Getting into the finer details of planning a timber cladding project.
You need to calculate the area you’re wanting to clad in square metres (m²). With square and rectangular spaces, this is done simply by multiplying together the wall dimensions.
To avoid running out of material, it’s always wise to account for a little waste (this is largely the result of cutting and trimming losses).
We’d recommend an extra 10% on top. So, once you’ve calculated the area of the surface with any openings subtracted, multiply your figure by 1.1.
You’ll then choose a product. Top tip: choosing a wider cladding board (with a greater cover size) can reduce your costs.
Read more: How much timber cladding do I need?
A good cladding wood should be durable and stable externally. Some commercially-popular examples include western red cedar, Thermo-ayous, Thermo-pine and Accoya®.
Read more: The best types of exterior wood cladding: your options
We would not recommend using standard ‘untreated’ softwood outdoors. Cheap options found in home improvement stores, like spruce, are not durable and are susceptible to rot and decay.
There are some exceptions to the softwood rule – western red cedar and Siberian larch are two examples can that perform well outdoors due to their natural stability and rot resistance.
Read more: The best types of exterior wood cladding: your options
The cost of cladding a house depends on a number of factors, most importantly the coverage required and species chosen.
In a quality timber species like western red cedar or Thermo-ayous, cladding costs an average of £50-65m² + VAT.
Other considerations include cover size, any factory coatings and whether fire protection treatment is applied during manufacture.
Read more: How much does timber cladding cost and how much do I need?
Based on an 18 x 144 board, western red cedar cladding costs approximately £75 per m² + VAT.
Read more: How much does timber cladding cost and how much do I need?
As a rule, no you do not. The addition of exterior cladding usually falls under what are called ‘permitted development rights’, meaning you do not need to seek planning permission as the property owner.
In the UK, most people find that exterior cladding jobs are classed as ‘repairs, maintenance or minor improvements’. As long as the ‘materials are of a similar appearance to those used in the construction of the house’ – usually the case with timber cladding – planning permission isn’t needed.
However, depending on location, there may be some restrictions. This is especially true if your property is on protected land — for example in an Area of Outstanding Natural Beauty (AONB), a National Park, a Conservation Area or it is a listed building.
In any case, we’d recommend seeking advice from your local planning authority (LPA) before starting your project. You can discover your area’s LPA through the Planning Portal, an organisation related to the Department for Communities and Local Government.
Read more: Do I need planning permission for exterior wood cladding?
Yes, timber cladding can be supplied with a Euroclass B fire treatment and have a compatible factory coated paint system.
This is due to recent advancements with colour coating systems that have increased the design possibilities for timber.
One industry-leading product is Burnblock® with Remmers – a specialist high-performance paint coating.
Read more: Burnblock® with Remmers: a fully-certified fire retardant and colour coating system
Yes. If you are fixing your cladding vertically, it’s important to choose a length closest to your requirement. This will reduce waste and, importantly, cost.
The number of linear meters to make a square metre is based on the cover size of the cladding board.
For example with a 128mm cover, there are 7.813 linear meters per square metre.
Read more: Cladding cover size and costs: a hack to maximise your budget
The industry standard for machining and delivering timber cladding is 4-6 weeks.
However, some specialist cladding suppliers – such as here at Duffield Timber – are able to provide cladding in 7-10 working days.
Installation and maintenance
Fixing your cladding and maximising its service life.
Yes. Firstly, you should screw timber battens into the brick, with a breather membrane underneath.
Timber battens are narrow wooden strips that form the structure underneath the finished cladding surface.
The cladding boards are then fixed to this structure.
Yes, as long as the existing surface is in a good condition. Existing pebbledash should be well bonded with no damaged, loose, crumbling, cracking, damp or hollow sections.
Surfaces that are unstable must be removed or repaired before being clad over – they won’t hold the timber battens and cladding securely.
Read more: Can you install cladding over pebbledash and rendering?
Yes. For exterior cladding that will be open to the elements, a ‘breather membrane’ will be required.
This should be water resistant to prevent moisture from reaching the surface underneath, such as the bricks of your house. It should also be vapour-permeable to allow for airflow and to prevent buildup of damp.
No. Timber battens should be used to fix the cladding boards – this allows fur airflow and reduces the risk of moisture getting trapped behind it.
Timber battens are narrow wooden strips that form the structure underneath the finished cladding surface.
If installed properly with a breather membrane and timber battens, no – the cladding will have enough room to breathe and allow for airflow. This will eliminate any risk of moisture buildup.
Timber cladding can be neatly finished at the corners by mitring the edges, leaving a square edge to butt up together or by fitting an angle bead.
No, never glue cladding together, especially if being used externally. Timber is hygroscopic and needs to be able to move freely when it takes on moisture.
As a result of moisture and the sun’s UV, timber cladding will take on a silvery-grey tone after several months of exposure to the elements.
This is due to breakdown of lignin, a component in the wood. This lignin is then washed away by moisture to leave behind exposed cellulose, which is a grey colour.
The process, called photodegradation, is essentially just a surface phenomenon. It doesn’t mean that the wood is decaying or rotting in any way whatsoever.
If you don’t like the grey look, applying a quality finish or stain can dramatically slow down (and almost halt) the process.
Read more:
In a naturally-durable and stable species such as western red cedar, Siberian larch, Thermo-ayous, Thermo-pine or Accoya®, expect at least 25 years of service life from your cladding.
With occasional maintenance and favourable environmental factors (weather conditions, exposure, elevation and aspect), the lifespan for timber cladding can easily range up to 35-40 years.
Due to its slow growth within a very cold climate, Siberian larch is naturally very durable outdoors. Untreated, it typically has a service life of over 25 years.
In favourable conditions and with appropriate maintenance, it can last for over 35 years before needing to be replaced.
Related article: The best Siberian larch cladding treatments, stains and oils
Didn't find the answer you were looking for? Ask us and we'll get back to you as soon as possible.
Submit your cladding question
