Understanding Timber

Typical wood characteristics

The special characteristics of wood as a natural product A growing number of people are recognising the qualities of natural materials and rediscovering wood as a building material. Wood has a number of outstanding characteristics: thermal insulation, sound insulation, high strength with good elasticity, high resisting force under loads, easy workability and many more. People who have come to appreciate wood are willing to accept its special characteristics. These are by no means indicative of a flaw or reason for compliant.

Knots and the natural grain of wood: A tree does not grow straight as an arrow. Its wood grain and number of visible knots vary. Knots firmly imbedded in the wood do not indicate a quality deficiency in the garden timber category.

Pressure treated wood: Salt efflorescence During pressure treatment, copper salts penetrate deep into the wood and protect it against mould and insect damage. Green and whitish spots sometimes appear on the surface of the wood, but are no cause for concern as they result from resin that has been dyed by the copper salts. These can be brushed off and often disappear with weathering.

Resin streaks: During storage and processing, wood changes in volume and thickness. One phenomenon of coniferous wood during this process is the emergence of resin to the surface. This is absolutely normal and can be corrected be scraping and careful removal with turpentine.

Mould and blue-stain: Especially during the warm periods, the surface of the wood can be discoloured by a blue-stain mould. The mould, however, does not destroy the wood and therefore does not influence its strength. Pressure treatment stops the fungal infestation. Areas that were previously affected are darker of colour. During storage of freshly pressure-treated timber, there may be some occurrences of mould stain caused by the fungus. These stains are, however, no cause for concern and can be wiped off or gradually disappear on their own when exposed to the elements.

Swelling and shrinking- ‘Wood movement’or 'shakes': Like many natural materials, the cells of the tree contain water. Depending on the humidity in the air, this moisture is gradually released and/or absorbed and results in the changes in volume. This can result in timber shakes (splits)The shakes will expand and retract as moisture reacts with the core timber

Rough spots: When sawing, planing and milling logs, we do everything we can to avoid damaging the wood. Nevertheless, wood fibres that run opposite to the machining direction sometimes cause rough spots. When crosscutting and rounding over the tops of posts, for example, slight fraying is unavoidable.

Colour variations: Each tree is unique. Its shape, colour and wood grain retain their uniqueness after processing. Wood varies in density. Therefore, it does not uniformly absorb the chemical preservatives when pressure treated. Over time, variations in colour will disappear when the wood is exposed to sunlight.

Checking warping: Because of the varying density of wood and its texture, swelling and shrinking as described above does not occur uniformly. This can result in cracks, or checking, which do not affect the structural characteristics and strength of the wood.