BS EN 335:2013 pdf free

BS EN 335:2013 pdf free.Durability of wood and wood-based products —Use classes: definitions, application to solid wood and wood-based products.
4 Use classes: application to wood and wood-based products
4.1General
The differences between the use classes are based on differences in environt
nent exposures that can make
the wood or wood-based products susceptible to biological deterioration.
NOTE Border line and extreme cases of use of wood and wood-based products exist. This can cause the assignmentof a use class that differs from that defined in this standard (see Annex B).
4.2Use class 1(UC 1)
Situations in which the wood or wood-based product is inside a construction, not exposed to the weather andwetting.
The attack by disfiguring fungi or wood-destroying fungi is insignificant and always accidental.
Attack by wood-boring insects,including termites, is possible although the frequency and importance of theinsect occurrence depends on the geographical region1.
4.3 Use class 2 (UC 2)
Situations in which the wood or wood-based product is under cover and not exposed to the weather(particularly rain and driven rain) but where occasional, but not persistent,wetting can occur.
In this use class, condensation of water on the surface of wood and wood-based products may occur.Attack by disfiguring fungi and wood-destroying fungi is possible.
Attack by wood-boring insects, including termites, is possible although the frequency and importance of theinsect risk depends on the geographical region1.
4.4Use class 3 (uc 3)
4.4.1General
Situations in which the wood or wood-based product is above ground and exposed to the weather (particularlyrain).
Attack by disfiguring fungi and wood-destroying fungi is possible.
Attack by wood-boring insects, including termites, is possible although the frequency and importance of theinsect risk depends on the geographical region1).
A large variety of in-use situations exists and, when relevant, use class 3 may be divided into two sub-classesuse class 3.1 and use class 3.2.
NOTE Decay risk depends on the climatic and other in-use conditions (temperature，RH,rainfal,structuralconditions, design details and maintenance provisions).BS EN 335 pdf free download.