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Timber Durability Scale and Rating

Timber Durability

Durability is a measurement of how long specific species of timber would last if a 50mm x 50mm cross section was left in the ground unprotected.

An untreated Oak beam, which is classed as 'durable’, for example, will last 15-25 years depending on environmental conditions.

The following scale of durability was outlined by TRADA, the Timber Research And Development Association.

Durability Class Designation Average timber service life Example Timber
5 Not durable less than 5 years American Ash
4 Slightly durable 5-10 years Siberian Larch
3 Moderately durable 10-15 years Douglas Fir
2 Durable 15-25 years European Oak
1 Very durable more than 25 years Teak (not available online)

For enquiries, call iWood's office
on 01889 279 018

or click here to find your area manager
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