Fastening to thermally insulated walls and ceilings
The basis for this is DIN 4102-12 and the Model Cable System Guideline (MLAR). The general building inspection test certificates (abP), which prove the usability of tested systems in construction, are decisive in this regard. In practice, however, structural conditions often lead to deviations from these specifications. Since neither DIN 4102-12 nor the MLAR, the Model Building Code (MBO), or the Model Administrative Regulation for Technical Building Regulations (MVV TB) provide specific guidelines in this regard, planners and installers often have to resort to individual design solutions.
Technical starting situation
A cable system with E90 functional integrity is to be installed in an underground car park. The plan is to install it using cable trays, suspension rods, and brackets, but the ceiling is completely covered with 140 mm thick thermal insulation made of mineral fiber boards. Cutting or removing the insulation is not permitted for structural reasons. This raises the question of how the cable system can be securely fastened in accordance with standards under these conditions.
Recommended solution: Fastening below the thermal insulation with spacer sleeves
As an alternative to the conventional method of fastening the suspension rod directly to the raw ceiling, installation can also be carried out below the thermal insulation. In this case, the suspension rod is screwed to the raw ceiling using spacer sleeves of the appropriate length. This design enables a defined transfer of force into the load-bearing structure without excessively compressing the insulation. At the same time, the required torque can be applied during screwing, which ensures a permanently secure connection.
An additional advantage: the mineral fiber insulation protects the spacer sleeve and screws from direct temperature stress in the event of a fire. This means that the connection is unlikely to fail. The dowels anchored in the raw ceiling also remain thermally shielded by the insulation layer, preventing the fastenings from being torn out in the event of fire stress.
Structural background and practical recommendations
In many modern buildings—especially underground garages, technical rooms, and industrial halls—ceilings and walls are equipped with composite thermal insulation systems (ETICS). These serve the purposes of fire protection, energy efficiency, and condensation prevention, but at the same time place special demands on the installation of function-preserving systems.
As a general rule, ETICS systems in which cable systems for safety power supplies and their components are installed must be made of non-combustible materials. Materials of European fire protection class A1 or A2 in accordance with EN 13501-1 or fire protection class A in accordance with DIN 4102-1 are permitted. In addition, it must be ensured that the insulation material has no negative influence on the functional integrity of the installed systems.
The installation described above with spacer sleeves underneath the insulation offers an efficient and safe solution: It ensures a statically load-bearing and fire-resistant connection to the raw ceiling, prevents impermissible heat effects on the fastening system, and preserves the integrity of the insulation material. This makes it a tried-and-tested method for reliably meeting the functional integrity requirements of DIN 4102-12, even under difficult installation conditions.
