Wood Preservative
Wood preservers are chemicals that are toxic to wood destroying organisms such as fungus and woodworm. Applications for wood preservative include constructional timbers, fencing, decking, playgrounds, railway sleepers, transmission poles and bridges. They can also be applied to furniture.
Wood Preservers
Pre-treating wood is important, as timber is vulnerable to infestations from insects and fungus. These attacks can compromise the structural integrity of a building. Whilst wood preserver may seem expensive, its cost is far lower than that of repair after infestation.
Wood preservative increases the service life of wood, reducing the total number of trees that need to be felled. It also allows species of tree which would otherwise be unsuitable to be used in construction, as before chemical wood treatment only durable hardwood was appropriate for external use.
Wood Preserver Types
There are many types of wood preserver, which can be grouped into three subtypes: chemical wood treatment, natural wood treatment and creosote. The type of wood preservative is determined by how high the risk is, the tree species used and the eventual application of the timber. The Wood Protection Association can offer free, impartial advice on the type of timber treatment which will be most suitable.
There are 5 classes of exposure risk as determined by the Wood Protection Association:
1. Internal, no risk of wetting.
2. Internal, risk of wetting.
3. External, above the damp proof course.
4. Permanent contact with the ground or freshwater.
5. Permanent contact with sea water.
Chemical Wood Treatment
Low pressure waterborne salt timber treatment and organic solvent solutions are recommended for exposure risks 1, 2 and 3. These are both forms of chemical wood treatment.
Creosote
Creosote can be used for all applications, although is particularly useful for risks 4 and 5, which includes applications such as railway sleepers and transmission poles. The persistent smell of creosote means it is rarely used indoors.
Natural Wood Treatment
Natural wood treatment is less effective than the alternatives, and for this reason it is usually only used in gardens and in internal wood which has little risk of wetting.
Safety Considerations
Creosote and some chemical wood preservatives have restricted use due to safety and environmental concerns. Research into natural wood treatments is increasing because of the environmental impacts of chemical wood treatments and creosote.
Creosote should never be used for home DIY use, as it has carcinogenic properties. Most DIY wood preservatives are chemical, and are applied using a brushes or sprays. Care must be taken, and at least two coats must be applied.