Box Beam and box Post is a system for roof and floor elements for longer spans. Based on Conzett’s design, these elements are based on Kerto S & Kerto Q LVL loadbearing components. We used these elements for the construction of Pratgraussals’s Event hall, the length of the span is 24 meters. The property of these composite elements is that the section is divided into intermediate flange parts (KERTO-S) with two outer thin web part (KERTO-Q). The section of the box beam is divided into two outer Kerto-Q web of 51 mm thickness each and two intermediate Kerto-S layer of 75 mm thickness each. The section of the box post is divided into two outer Kerto-Q web of 45 mm thickness each and four intermediate Kerto-S layer of 75 mm thickness each. All the layers are connected with bolts. For our project of Pratgraussals’s event hall, one advantage of the hollow sections in contrast of I sections was a much better torsional stiffness, which is good for avoiding lateral torsional buckling specially during the transitional phase of lifting.

Key benefit

Fast construction process

Material list

Kerto Q for web
Kerto-S for flange and stiffener
Coach screw or bolt

Ecological values

- Hollow elements: matter and weight economy - Prefabricated elements: clean site, noise and nuisance limitation, reduced construction time - Local sector for compound elements



  • Economical span (mm) 24000
  • Thickness (mm)
  • Airbourne sound reduction factor (dB)
  • Impact sound transmission (dB)
  • Resistance to fire class
  • Thermal properties



  • An effective way of using LVL. Especially using cross layered LVL like Kerto-Q as the web part that takes the shear force and LVL like Kerto-S as the top and bottom flange for the compressive forces. With the large 24m panels all the flange and web elements can be without a joint.
  • A good solution for large spans, thanks to an intelligent combined product mix with efficient use of materials, for a sophisticated supporting structure.


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