Production

Bildquelle: Studiengemeinschaft Holzleimbau e.V.

Drying of the boards

 

Softwood- boards are dried down to a moisture content of approx. 12 % and then planed.

Bildquelle: Studiengemeinschaft Holzleimbau e.V.

Strength-grading

 

The planed dried boards are strength-graded either visually or mechanically. For the outer lamellas of the glulam additional requirements concerning the outward-appearance of the glulam are taken into account.

Bildquelle: Studiengemeinschaft Holzleimbau e.V.

Cutting off knots and other wood-defects

 

Board sections with wood-defects having significant influence on the strength or the outward appearance such as knots, resin- or bark-pockets are cut out off the boards dependent on the strength class and the surface-class. The boards are jointed together lengthwise to a theoretically infinite lamella using fingerjoints (glued connection between the edges of two boards which have a shape similar to a hand).

Bildquelle: Studiengemeinschaft Holzleimbau e.V.  
Bildquelle: Studiengemeinschaft Holzleimbau e.V.

Planing of the lamellas

 

After the fingerjoints have been hardened the lamellas are planed to thicknesses of up to 45mm.

Bildquelle: Studiengemeinschaft Holzleimbau e.V.

 

The glue is applied on the broader edge of the lamella.
Bildquelle: Studiengemeinschaft Holzleimbau e.V.

Pressing

 

At least three lamellas are stacked and pressed in an either straight or curved press.

Bildquelle: Studiengemeinschaft Holzleimbau e.V.

Planing of the glulam

 

After the gluelines are hardened the raw glulam is usually planed and chamfered.

 

Bildquelle: Studiengemeinschaft Holzleimbau e.V.

Factory assembly and further detailing

 

In most cases the glulam members are cut to their final size and joints are fixed in the plant. If necessary the members are given preservative treatment or temporary coating against the influence of direct weathering during construction and the members are wrapped with packing material.

 


WF: W. u. J. Derix GmbH & Co.Glue lines are very thin. The portion of glue in a glulam-member is less than 1%.

 

Glulam is strength-graded and refined by lamination. Therefor its permissible bending strength is up to 50% higher than the permissible bending strength of the usually used solid-wood.

 

As a result of the production-procedure glulam members are deformed less through shrinkage and have a higher resistance to cracking. As the single lamellas are very flexible unless bonding together, it is very easy to produce curved glulam members. Spatially curved or twisted members require greater efforts.