Horizontal fire barriers prevent the fire from spreading vertically over several floors in the cavity between the façade cladding and the solid wall.
The following (exemplary!) Rules are taken from the sample list of the Technical Building Regulations Part 1, Appendix 2.6/11. The specific rules for fire barriers applicable in the respective federal state can be found in the technical building regulations introduced there and may deviate from them:
Source: bauwion
