Material Properties

When it comes to talking about the advantages of Laminated Timber as a construction material, its material properties have to be mentioned. Laminated Timber possesses significant attributes. Strength property, stiffness and its molded density define Laminated Timber as a superior construction material.

As timber may be quite variable in mechanical properties, pieces of timber are placed in categories in order to differentiate the quality of structural timber. These categories are called quality grades.

In former times there used to be only two categories: grade I and grade II. Later on, these categories were replaced by the terms BS 11 and BS 14. Whereas the letters BS referred to the expression "BRETTSCHICHTHOLZ", the German word for Laminated Timber, the numbers 11 and 14 indicated the bending strength. So the new terms BS 11 and BS 14 indicated the stress grade of the building material. Back in those days, the timber was graded visually.

Thanks to the most modern technology, the timber is machine-graded today. Automatic grading is reliable and efficient and we are able to offer Laminated Timber in BS 11, BS 14 and BS 16 quality.

Nowadays, the construction industry in Europe strives for harmonised standards, and as a company with a lot of export activities we appreciate that. So today in Europe we use technical terms that signify the strength class of the building material. First of all, the letters BS are replaced by the letters G and L: The letters GL are the abbreviation for GLULAM (Glue Laminated Timber). Then, the numbers are doubled, so that BS 14 becomes GL 28, BS 16 becomes GL 32. BS 11, however, is changed into GL 24. The new numbers are used in order to better indicate the bending strength of the material. Except for the common sizes and grades that are available on stock, Laminated Timber is custom manufactured. This allows our customers to use the product to its maximum efficiency. For more information please don't hesitate to contact us, our experts are looking forward to offer advice and assistance.

Information on strength properties is necessary in order to determine the load-bearing capacity. And data on stiffness properties help to calculate the capacity to deformation.

Prior to fabrication the timber is mechanically evaluated in our facilities. With the help of the most modern technology we determine the molded density properties in order to ensure that the product can be used to its maximum efficiency.

Please find below the data on strength, stiffness and molded density of Laminated Timber (homogenous and combined material), GL 24 to GL 36 according to DIN 1052:2004-08:

  1 2 3 4 5 6 7 8  
1 Strength Class GL24h GL24c GL28h GL28c GL32c GL36h GL36c  
Strength Properties in N/mm2
2 Bending fm,k 24 24 28 28 32 36 36  
3 Tension parallel  ft,0,k 16,5 14 19,5 16,5 19,5 26 22,5  
4 Tension rectangular  ft,90,k 0,5
5 Pressure parallel fc,0,k 24 21 26,5 24 26,5 31 29  
6 Pressure rectangular fc,90,k 2,7 2,4 3,0 2,7 3,0 3,6 3,3  
7 Shear and Torsion  fv,k 2,5
Stiffness Propertie in N/mm2
  Modulus of Elasticity  
8 Parallel E0,mean 11600 11600 12600 12600 13700 14700 14700  
9 Rectangular E90,mean 390 320 420 390 420 490 460  
10 Shear Modulus Gmean 720 590 780 720 780 910 850  
Molded Density Properties in kg/m3720
11 Molded Density 380 350 410 380 410 450 430