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Finishing and maintaining wooden exterior walls
PROTECTING AND EMBELLISHING WOODEN WALL CLADDING HOW DO WE PRESERVE THE NATURAL LOOK OF WOODEN WALL CLADDING?
Photo – Blanchon
It is clear that the demands made of a wooden wall cladding finish are not entirely the same as those for wooden terraces. We won’t be walking on our wall, so the demands in terms of wear resistance are completely different. Obviously, wall cladding is exposed less to all sorts of potential mechanical dangers such as falling items or chemical products. Nor do you spill wine or coffee on a wall. Wooden wall cladding has some natural enemies, so the wood has to be protected and maintained, but those enemies are found elsewhere and mainly in the form of the weather conditions.
the larvae, since the wood worm is basically a beetle. The wood worm lives in the wild, especially in trees with hard wood, such as oak and fruit trees. Wood rot is a fungus which mainly affects wood exposed to (excessive) damp. In some cases the fungus is visible. Sometimes, wood rot betrays itself by the fact that the wood surface turns brown and crumbly or looks dirty white and spongy. The fungus often penetrates to the inside of the wood via the ends, such as the underside of a pole, the place where two beams touch each other, the connecting points of window frames, and such like. Wood which is often exposed to wind is particularly vulnerable.
Light, air, water, and bugs
‘Protecting’ is merely one aspect of a treatment for outdoor wood. We also want our wooden wall cladding to look nice and stay nice. The choice of wood sort is a first step to that end. Some wood sorts are simply nicer than others, even if that is clearly just a matter of taste. The most coveted wood sorts are usually also the most expensive ones. They do have the advantage of being ‘more durable’ than cheaper sorts. One of the aesthetic reasons for treating outdoor wood is to counteract the aforementioned ageing. Some people like the look of ageing wood, yet we do know that it is an ‘expression’ of gradual decay. Embellishment is possible by applying a product to counteract the ageing. This achieves a dual objective. The more you use colours, the more effective the protection from UV light. The addition of pigments hinders the penetration of sunrays.
Ultraviolet light, oxygen, and water together form the main cause of ageing and possible wood rot. In a photochemical process, sunlight breaks up the dark-coloured lignin, one of the main components of wood. The light-coloured cellulose, the other component, is left behind on its own. The fact that the wood turns grey shows that the colour of the cellulose will prevail. What we perceive visually as ‘greying’ or ‘ageing’ is actually a microscopically thin layer of wood decomposing. The greying can be darker or lighter, depending on the surrounds and the extent of pollution in the air. Apart from those atmospheric conditions, there is also the threat of living organisms. The major threats to outdoor wood are wood worm and wood rot. The wood worm is a larva of the furniture beetle. The designation ‘worm’ also refers to
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Protecting and embellishing
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