What is tree bark?
Bark is the outer layer of a tree, surrounding the wood of the trunk and branches. It protects the tree against drying out, damage and disease. Compared with wood, bark contains a lot of air. A special kind of bark is cork: the thick bark of the cork oak, which grows back after harvesting. A cork oak can only be stripped again after a number of years.
In construction, bark matters mainly when assessing timber. If a trunk is damaged, bark can become enclosed in the wood as it grows. Such a bark pocket (ingrown bark) is a weak, loose spot that reduces the quality and appearance of the timber. In architecture, the tree trunk is also regarded as one of the inspirations for the classical column.
Application
Bark on construction timber:
- Debark roundwood used for posts, fences and structures: bark holds moisture and shelters insects, so the wood underneath deteriorates faster.
- Check for bark pockets and bark left on the edges (wane) when buying. For exposed and load-bearing timber these are quality defects.
- Remove bark before finishing: paint and stain do not bond to bark, and loose bark takes the coating with it when it falls off.
Bark in the garden:
- Bark mulch is used as ground cover: it keeps the soil moist, suppresses weeds and opens up the soil as it breaks down.
- Lay a thick enough layer (5 to 10 cm is often recommended) on weed-free soil; a thin layer barely stops weeds.
- Keep bark away from timber cladding, fence boards and the floor of a garden shed: damp bark against timber speeds up rot.
- Top up regularly, as bark decomposes.
Cork: the bark of the cork oak is made into cork flooring and cork boards, among other things, which dampen heat loss and impact sound.
Related Terms
- Cork
- Wood rot
- Wood species
- Wooden floors
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