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Strength graded structural timber

Strength graded structural timber

Strength graded structural timber is sawn timber (without finger joints) which is produced for loadbearing applications by cutting or profiling of round wood in saw mills. For construction purposes solid timber has to be classified according to its strength by visual or machine grading according to EN 14081-1. In Austria and Germany visual grading continues to take place according to ÖNORM DIN 4074-1. Different strength classes apply. Sawn timber can be refined further by subjecting it to additional processing steps, e.g. kiln drying, planing, chamfering and additional profiling. The natural durability (against biological attack) of structural solid timber depends on the wood species used. The durability can be enhanced by treatments with preventative biocides. The requirements of standard EN 15228 have to be followed. In addition to the requirements of the standards, further quality criteria are specified by the communities "MH®-Massivholz Austria" and KVH®.

Finger-jointed solid construction timber

Finger-jointed solid construction timber

Finger-jointed solid timber is graded, kiln-dried and planed solid timber, which can be manufactured in almost any length. Specifications for finger-jointing are given in EN 15497. Finger-jointed solid timber is classified into strength classes by visual or machine grading according to EN 14081-1. In Austria and Germany visual grading continues to take place according to ÖNORM DIN 4074-1. Different strength classes apply. The natural durability against biological attack of this type of timber product depends on the wood species used. The durability can be enhanced with standard techniques such as preventative biocides. The requirements of standard EN 15228 have to be followed. In addition to the requirements of the standards, further quality criteria are specified by the community KVH®. The CE-certification of this product group according to the harmonized standard EN 15497 has been compulsory since 10.10.2015. This standard defines performance requirements and also sets a maximum wood moisture content of 18%. The adhesive used to bond the lamella has to fulfil the requirements of load-bearing structural timber components.

 


Glued solid timber

Glued solid timber

Glued solid timber consists of lamellae of the same strength class or manufacturer-specific strength class which are bonded together. According to EN 14080 glued solid timber comprise up to five lamellae with thicknesses from 45 to 85 mm. The total cross-section of the beam shall not exceed 280 x 280 mm. Glued solid timber is predominantly bending stressed (upright position of the square wood). The lamellae of glued solid timber are classified into strength classes by visual (according to ÖNORM DIN 4074-1) or machine grading and categorized in C-classes (according to EN 338). Strength and stiffness properties can be taken from EN 338. In the harmonized standard EN 14080 glued solid timber is standardized for the first time. The CE-certification of this product has been compulsory since 08.08.2015.

Glued laminated timber

Glued laminated timber

Glued laminated timber (glulam) according to EN 14080 is manufactured from bonded lamellae with parallel fibre orientation. There are at least two lamellae with thicknesses from 6 to 45 mm. The timber is planed and classified into strength classes by visual or machine grading. The adhesive used to bond the lamellae has to fulfil the requirements for loadbearing structural timber components. The suitability of the wood species in glulam construction has to concur with EN 14080. Spruce, fin, pine and larch are most commonly used. One can distinguish between homogenous (all lamellae across a beam's cross-section belong to one strength class) and combined (outer and inner lamellae belong to different strength classes) glued laminated timber. For each of these two configurations EN 14080 defines seven different types of strength classes. EN 14080 also applies to glued laminated timber with universal finger-jointing and composite components consisting of glued laminated timber and glued solid timber. Glued laminated timber is particularly suited for components bearing high stresses or spanning large distances which have to satisfy stringent requirements with respect to dimensional stability and appearance. Straight as well as curved beams can be manufactured. The CE-certification of this product according to the harmonized standard EN 14080 has been compulsory since 08.08.2015.

Light composite wood-based beams and columns

Light composite wood-based beams and columns

I-beams or double T-profiles are wood-based composite elements, consisting of two flanges and a intermediate web which are glued together. They are intended to be used as loadbearing parts of building constructions, the utilization is limited to service class 1 and 2 (according to EN 1995-1-1). The top and bottom flanges are mainly made of strength graded structural timber (according to EN 338 or EN 14081), glued laminated timber (according to EN 14080) or Laminated Veneer Lumber (LVL, according to EN 14374). The webs are mainly made of Oriented Strand Board (OSB/3 or OSB/4) in accordance with EN 300 or hardboards according to EN 622-2. Glued joints of flanges to webs or webs to webs have to meet the requirements of EN 301 or EN 15425. The elements are used as columns, floor and roof beams. Materials, dimensions and mechanical properties of the product are manufacturer-related and are given in the European Technical Assessment (ETA) of the manufacturer. The reaction to fire is classified in accordance with the used materials, e.g. Euroclass D / smoke production s2 / flaming droplets d0. I-profiles or double T-profiles have the possibility to get a CE-certificate in accordance with ETA (according to ETAG 011 "Guideline for European Technical Approval of light composite wood-based beams and columns", used as European Assessment Document (EAD)) and the associated CE-certification. Additional European or national laws/regulations/implementations may apply.

Parallel Strand Lumber (PSL)

Parallel Strand Lumber (PSL)

PSL is a product manufactured from strips of veneer measuring approximately 3 mm in thickness and 15 mm in width. Phenolic resin is used to bond the individual veneer strips. The strips can be up to 2,6 m long, before the strips are bundled together with their individual ends offset and with fibres oriented primarily parallel to the major axis of the beam. In a continuous press the veneer strips are pressed to form an endless beam. Douglas fir and Southern Yellow Pine are the most commonly used wood species. Parallel strand lumber is designed to be used in structures with long free spans. In order to obtain components with large cross-sections, PSL members can be bonded together.