According to DIN 4102-4, the usual types of raw slabs are divided into three types of construction with regard to their fire protection properties:
Type I:
- Slabs with steel beams exposed in the false ceiling area with a U/A value ≤ 300 m-1 and an upper cover made of pumice concrete hollow planks or aerated concrete slabs,
- reinforced concrete ribbed ceilings or reinforced concrete beam slabs with intermediate parts made of lightweight concrete or bricks,
- Reinforced concrete slabs with steel beams embedded in the concrete.
Type II:
- Ceilings with steel beams exposed in the false ceiling area with a U/A value ≤ 300 m-1 and an upper cover made of in-situ concrete or prefabricated slabs with a statically cooperating in-situ concrete layer or prefabricated elements as hollow planks made of reinforced or prestressed concrete.
Type III:
- Reinforced concrete and prestressed concrete slabs or roofs made of normal concrete,
- reinforced concrete and prestressed concrete hollow slabs made of normal concrete,
- reinforced concrete beam slabs with beams and intermediate components made of normal concrete,
- reinforced concrete ribbed slabs without intermediate components or with intermediate components made of normal concrete,
- mushroom and coffered ceilings made of normal concrete.
The design is important, for example, if a ceiling cladding/suspended ceiling is to achieve a certain fire resistance class in combination with the raw ceiling. The construction of the raw ceiling is then co-determining for the exact execution of the ceiling cladding/sub-ceiling.
Source: bauwion
