BS/EN 335-2013 pdf download.Durability of wood and wood-based products Use classes: definitions, application to solid wood and wood-based products.
2 Normative references
The following documents, in whole or In part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1001-2:2005, DurabilIty of wood and wood-based products — Terminology — Part 2: Vocabulary
EN 1995-1-1, Eurocode 5 — Design of timber structures — Part 1-1: General — Common rules and rules for buildings
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1001-2:2005 and the following apply.
service situation
situation of exposure of the wood element in use
3.2
wood-based product
any products containing wood
Note 1 to entry: For instance solid wood panel, laminated veneer lumber (LVI). plywood, oriented strand board (OSB), resin-bonded particleboard, cement-bonded partideboard or fibreboard. modified wood are wood-based products.
4 Use classes: application to wood and wood-based products
4.1 General
The differences between the use classes are based on differences in environment 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 assignment of a use class that differs from that defined in this standard (see Annex B).
4.2 Use class I (UC 1)
Situations in which the wood or wood-based product is inside a construction, not exposed to the weather and wetting.
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 the insect occurrence depends on the geographical region.
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 the
insect risk depends on the geographical regionU.
4.4 Use class 3 (UC 3)
4.4.1 General
Situations in which the wood or wood-based product is above ground and exposed to the weather (particularly rain).
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 the insect risk depends on the geographical region”.
A large variety of in-use situations exists and, when relevant, use class 3 may be divided into two sub-classes use class 3.1 and use class 3.2.
NOTE Decay risk depends on the climatic and other in-use conditions (temperature, RH, rainfall, structural conditions, design details and maintenance provisions).
4.4.2 Sub-class 3.1 (UC 3.1)
In this situation the wood and wood-based products will not remain wet for long periods. Water will not accumulate
NOTE This may be achieved by. for example, a maintained and suitable coating, or by design or orientation of components to shed water or to dry quickly.
4.4.3 Sub-class 3.2 (UC 3.2)
NOTE Components are not designed or orientated to shed water o dry quickly.
4.5 Use class 4 (UC 4)
A situation in which the wood or wood-based product is in direct contact with ground and/or fresh water.
Attack by disfiguring fungi and wood-destroying fungi is possible.
1) If national standards do not specify the risk of Insect attack, local or national experts should be consulted for advice on the risk of insect attack.
Attack by wood-boring insects, including termites, is possible although the frequency and importance of the insect occurrence depends on the geographical region
NOTE Wood and wood-based products which are constantly below water level or completely buried and fully saturated by water are not susceptible to be attacked by fungi but may be damaged by bacterial decay.
4.6 Use class 5 (UC 5)
A situation in which the wood or wood-based product Is permanently or regularly submerged in salt water (i.e. sea water and brackish water).
Attack by invertebrate marine organisms is the principal problem, particularly in the warmer waters where organisms such as Limr7oria spp, Terodo spp. and Pholads can cause significant damage. Attack by wood- destroying fungi and growth of surface moulds and staining fungi is also possible.
The above water portion of certain components, for example harbour piles, can be exposed to wood-boring insects.BS/EN 335-2013 pdf download.