Technical requirements for wood

1. General

The raw material for the production of milled timber profiles is usually centre sawn timber. Production can also be arranged from side timber, but the user must be aware of the risk of major shape and dimensional changes in the parts when the wood moisture content changes. The type of softwood shall be selected according to the expected appearance, its suitability for the desired purpose and its general characteristics. Unless otherwise agreed, all requirements shall apply at the time of delivery.

2. Appearance

Grading shall be by face. Unless otherwise agreed, all properties shall be judged on the face of the parts. The requirements for workmanship are contained in Article 4.4.3.

2.1 Classes

Theclasses and their characteristics for spruce (Picea sp.)/fir (Abies sp.), pine (Pinussylvestris). larch (Larix sp.) and Douglas-fir (Pseudotsuga menziesii) are given in Table 1.

No more than 5 % of the parts of the consignment may be of the next lower grade. Pieces that do not meet the requirements of Class B shall meet the final purpose of the lining. There may be only one property of these components that is not conforming. Grading by appearance shall not take into account defects which will not be visible on the assembly (e.g. chips or small dropped knots on the lip, isolated lip width defects).

2.2 Class AB

Class AB is defined as a class containing at least 40 % of Class A parts and 60 % of Class B parts. This grade is formed from the parts attacked during processing, from which parts not conforming to grades A and B are sorted. Grade AB shall not be further graded (i.e. no grade A parts shall be sorted from it).

2.3 Class C

Class C contains parts which do not meet the requirements of Class B. The components shall meet the end purpose of the lining.

2.4 Free class

Classes A, B, C and AB, which are listed in this standard, may not be acceptable. In this case, the class may be defined by contract. However, all defects listed in Table 1 must always be identified in the contract or in the technical specifications, etc. (e.g. Class B without knot holes).

3. Moisture

The reference moisture content of profiled timber is 12 %. The moisture content at delivery must be within (12±2) %, for flooring components (10±2) %.

Informative values of the equilibrium moisture content that will stabilise in the wood are:

Equilibrium wolfiness is usually achieved by sufficiently long conditioning in the end-use environment.