Standards and Symbols

Standards

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The questions on standards and technical classes of EGGER OSB can be found below.

Which are the most important standards for OSB and timber construction?

Among the many standards referring to wood products and timber, the most important are:

EN 13986:2004: Wood-based panels for use in constructions → Characteristics, evaluation of conformity and marking
EN 300 (product standard for OSB): Definition, classification and requirements
EN 12369-1: Wood-based panels → Characteristic values for structural design; Part 1: OSB, particleboards and fibreboads
EN 1995-1 (Eurocode 5): Design of timber structures → Part 1-1: General rules and rules for buildings
EN 1995-2 (Eurocode 5): Structural fire design of timber structures EN 335 (wood preservation)
EN 120: Determination of formaldehyde content (perforator method)
EN 717-1: Determination of formaldehyde release (chamber method)
EN 13501-1/2: Reaction to fire → Part 1: classification of building materials according to Euro-classes; Part 2: classification of building components (roofs, walls, floors)
EN 12871-1: Wood-based panels → Performance specifications and requirements for load-bearing boards for use in floors, walls and roofs

What are the Technical Classes of OSB?

Technical classes are the terminology used to describe the different types of OSB boards, according to their intended end use (load & climate conditions).

There are 4 technical classes: OSB/1, OSB/2, OSB/3 and OSB/4.

What is the difference between service class and usage class?

By service classes there are defined 3 different moisture conditions of the environment. For OSB, they describe the moisture conditions of the environment where the boards are intended to be installed.

The standard EN 1995-1-1 defines the 3 service classes, as follows:

Service class 1 (dry conditions, RH . 65%) - characterized by a moisture content in the material corresponding to a temperature of 200C and a relative humidity of the surrounding air only exceeding 65% for a few weeks in a year
Service class 2 (humid conditions, 65 < RH . 85%) - characterized by a moisture content in the material corresponding to a temperature of 200C and a relative humidity of the surrounding air only exceeding 85% for a few weeks in a year
Service class 3 (external conditions, RH > 85%) - climatic conditions leading to a higher moisture content than in service class 2

The usage classes describe the end-use situations of the wood and wood-based panels, related to climate. The standard EN 335-1 defines 5 usage classes. Among them, applicable to OSB are:

Usage class 1 - describes the situations where the wood and wood-based products are used under roof, completely protected from weather and not exposed to wetting.
Usage class 2 - describes the situations where the wood and wood-based products are used under roof, completely protected from weather and where the high surrounding moisture can lead to limited time-wise wetting.

What is the difference between the requirement values and the design values of OSB?

The requirement values indicate the quality of the boards as delivered from production.
They represent the reference values for the factory production control (FPC), in other words the minimal values the boards must posses in order to pass the quality testing in the factory.

The requirement values of OSB are given in the product standard EN 300.
The requirement values of the boards are not the values to be used in the structural design of structures!

The design values are the values used for the static design of the structural elements (floors, walls and roofs) made of OSB decking/sheathing spanning over supports (beams, studs, rafters).
Often they are referred also as the performance values used in the static design.
They include the effects of different loads upon the structure (self-weight, storage-weight, wind, snow) and takes into account the importance of the building (people occupancy) and the load duration.

EN 12369-1 is the standard that regulates the static design of structural elements with OSB, for board thickness ≤ 25mm.

For thicknesses > 25mm, the manufacturer must declare its values according to test procedures described by EN 789 and EN 1058.



Symbols and Axis

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Find out symbols and axis definitions from the FAQ's below.

What is the meaning of the symbols met in standards (tables)?

The most important characteristics and associated symbols related to OSB are:

a) Symbols:

ƒ - strength
E - modulus of elasticity (stiffness)
G - modulus of rigidity
k - retention in strength (kmod) or stiffness (kdef) after a period of time rel. to initial values
t - thickness
p - density
// or 0 - in the direction of the major axis of OSB
┴ or 90 - in the direction of the minor axis of OSB


b) Subscripts:

m - bending
t - tension
c - compression
v - panel shear
r - planar shear
nom - nominal
def - deflection


What does major and minor axis of OSB mean?

Unlike particleboards and fibreboards (which show uniform distribution of stress all-over the panel), OSB exhibits different bending and stiffness values on the two dimensions.

Typically, they are 2-2,5 times higher on length compared to width. In this respect:

Major axis = the dimension in the plane of the board in which bending properties have the higher value
Minor axis = the dimension in the plane of the board at right angles to the major axis