The Use of Timber Cladding in Buildings
Using timber as cladding has long been a popular way to finish a building, and has become a particular favourite on contemporary design projects. It can be an attractive and economical way to finish a property, which is also eco-friendly and is becoming increasingly popular on both commercial and domestic buildings. It appears that timber cladding has overtaken UPVC cladding and hanging tiles as a form of cladding for buildings.
It is often called weatherboarding as it offers a great deal of protection if installed correctly. It’s important to choose a timber that is naturally resistant to decay and western red cedar and larch are popular choices of timber, along with British timbers such as oak, chestnut and elm. They can all be found in a variety of profile ranges from traditionally rustic waney-edge through to feather-edge, shiplap and half-lap.
The design of a timber facade can present some technical challenges, such as weathering, maintenance and wind resistance, and it will need to be durable and present a high standard with regard to fire safety.
Most boards will be fixed with nails, and the ring shank variety provide the best grip for fixing cladding. It is best to use nails that are two and a half times the thickness of the boards and they should penetrate the boards by at least 32mm. If hardwood boards are used, such as oak, these will need to be pre-drilled. If the boards need to be double-nailed then it is better to pre-drill over-size holes to allow for movement, and this may mean using nails with larger heads. It is important that the fixings are either galvanised or stainless steel and if the timber has a high level of tannin or corrosive oil content then they must be stainless steel to avoid corrosion or blue stains on the timber around the nail body.
Using timber that is green or prone to dimensional shrinkage or movement needs a deal of thought with regard to the time of year it is fitted as well as the amount of shrinkage that will occur, which can be as much as 10% in the first 2 – 3 years. The best time to fit such boards would be in the autumn or winter to avoid over exposure to hot dry weather.
The most common design of cladding is to lay the boards horizontally, although they can be fixed vertically or diagonally. Horizontal cladding would be fixed to battens that are that fixed horizontally to the building walls. The battens should be pressure treated with preservative and screwed to the walls. The cladding also provides a cavity which allows any water or moisture to escape and also helps to maintain balanced moisture content to both the inner and outer surfaces of the cladding which helps to avoid the potential of warping or distortion. It is recommended that the cavity should be at least 19mm and a waterproof membrane is usually fixed behind the batten to protect the wall. The quality of the battens and the number of fixings to the walls are also important as the battens will be carrying a great deal of weight.
If fitted correctly and well maintained, timber cladding will last a lifetime and more.
Image credit: Bryn Pinzgauer