Timber Species Durability
For External Cladding
When considering timber for external cladding purposes, probably the biggest single factor, is its durability. Other important follow on factors are of course, Price and Availability.
The classifications in this sheet are those given in BS EN 350-1 for the timbers included.
Insect attack is generally of less significance in the UK. Information on the resistance of some timbers to insect and marine borer attack is given in BS EN 350-2 Guide to natural durability and treatability of selected wood species of importance in Europe.
Guidance on the need for preservative treatment in particular situations is given in BS 8417:2003. Note that BS 5268-5 and BS 5589 are now obsolete. These are shown, with a typical example of a timber species, in each. In the case of Western Red Cedar (WRC), where it is across two columns, if the timber is North American (generally always Canadian), then the timber is graded “Durable”. Imported Western Red Cedar is the only Softwood ranked within the “Durable” category. However, home grown WRC only achieves ‘Moderately Durable’ grading.
In the case of those other species spread over ‘Moderately’ and ‘Slightly’ durable, this depends on the quality of the timbers selected, with only the prime being ‘Moderately Durable’. In many instances, prime grade would be used for milled products as opposed to basic cladding.
The natural durability of Western Red Cedar is not the only reason we have chosen, and recommended it’s use.
Other strong considerations, where it is superior to the other species are :-
- Looks great and smells wonderful.
- Resin free – it naturally does not occur so it does not ‘weep’
- Stable – WRC stays straight and is very resistant to warping
- Natural Insect Deterrent – the naturally occurring chemicals within the wood, resists attack from most woodboring insects.
- Good thermal and acoustic insulator
- Accepts finishes well
If you any further questions about Western Red Cedar, then please contact us, and I’m sure we can assist.