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Hazard/use classes of wood exposure
Wood and wood based material is exposed to varying levels of danger during its application. The risk of wood infestation by biotic pests such as wood decaying fungi and wood decaying insects grows with the effects of exposure to weather conditions which affect the material. The ČSN EN 335-1 standard defines five hazard classes representing various wood exposures.
Hazard class | Description | Borers | Examples of wood applications |
|---|---|---|---|
1 | The wood is under shelter, fully protected against weather conditions, not exposed to humidity (max. wood humidity of 20%) | insect | floorboards, battens, joinery and cabinet making timber |
2 | The wood is under shelter, fully protected against weather conditions, ambient humidity can lead to occasional increases in wood humidity (wood humidity occasionally > 20%) | insect fungi | construction timber, cladding, roof timber with increased risk of water vapour condensation |
3 | The wood is in the exterior above the ground level, exposed to repeated humidity increases (wood humidity often > 20%) | insect fungi | exterior timber, soffits, cladding structures, roof shingles, railings, fencing plates |
4 | The wood is in direct contact with the ground or fresh water | insect fungi | electric posts, noise barriers, wooden foundations, children’s playgrounds, pillars, bridge structures |
5 | The wood is permanently exposed to the effects of sea water | sea borers fungi | piers, moles, wharfs, ships´ hulls |
