FAQ 004349 | Is it possible to perform fire resistance design of cross-laminated timber panels in...

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We provide hints and tips to help you get started with the basic program RFEM.



Bastian Kuhn

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Is it possible to perform fire resistance design of cross-laminated timber panels in RF‑LAMINATE?


Fire resistance design is not implemented in the RF‑LAMINATE add-on module by default.

However, you can calculate the charring rates yourself and consider them accordingly in the module. In the following example, this is explained on a simple plate.

Structural system (Figure 01):

  • Span 5 m
  • Plate width 2 m
  • LC1 (permanent) 1 kN/m² plus dead load
  • LC2 (medium) 2.5 kN/m²
  • 3 layers
    • S1 35 mm C24
    • S2 20 mm C24
    • S3 35 mm C24
The information regarding the correction factors and stiffnesses can be found in the attached file.

Factors for fire resistance:

  • Charring rate ß0 = 0.65 mm/min
  • Pyrolysis zone k0d0 = 7 mm
  • Charring time t = 30 min
  • Effective thickness def=t ß0+k0d0=30 min × 0.65 mm/min+7 mm = 26.5 mm
Remaining thickness of Layer 3 = 35 − 26.5 = 8.5 mm > 3 mm → thickness may be applied. (Figure 02)

Because of the modified layer thicknesses, a new stiffness matrix results, which is applied in RFEM for accidental combinations with the characteristic stiffness values. For the ultimate limit state, the design values are calculated here (Figure 03).


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  • Updated 05/27/2020

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