Timber cladding forms the external facade of buildings. It acts as a rainscreen cladding which is the outer wall of a double wall construction. The inner wall is separated by a cavity that is well ventilated so that any moisture that penetrates the cladding gets evaporated or drains away. This cladding is used on new or existing buildings as a second skin for reasons such as improving the aesthetics of the building, thermal properties, environmental credentials, ease of use and lightweight construction.
Cladding is laid in a number of different ways according to the aesthetics required for the building. Boards are orientated vertically, horizontally or diagonally. Thin pieces of wood called battens are fixed to the inner wall as support for the cladding. If the cladding required is horizontal, the battens are fixed vertically. The space between the outer and inner walls has insulation, a waterproof membrane and a ventilation cavity. Tongue and groove and ship-lap joints are used to fit the boards together. They are also open jointed or overlapped.
Types of Wood
Softwoods and hardwoods are used as cladding materials. The choice is dependent on budget, aesthetics, level of maintenance, durability and availability. Softwoods such as European redwood and European whitewood and Pine are suitable for use once treated with preservatives. Softwoods such as Western red cedar, European Larch and Douglas fir and hardwoods such as European oak and sweet chestnut are used without any additional treatment once the sapwood has been removed from them.
Natural Durability Classification
Wood suitable for cladding is classified according to its natural durability, which ranges from very durable to not durable. Timbers such as Western red cedar from North America and European oak are classified as durable. This means that the life span for this cladding is between 15 and 25 years after which regular maintenance and replacement is required. European Larch and Douglas fir from North America are classified as moderately durable which gives them a life span of 10 to 15 years.
Timber cladding is seen as an environmentally friendly material. It is important to take into consideration the whole life cycle cost to the environment when choosing timber cladding. Factors that have an impact on the environment are transportation costs, preservative treatments required, level of maintenance, durability and availability. Always consider locally available options first, and source the timber from sustainably managed forests that are certified by organizations such as the Forest Stewardship Council.