Is a 7-Story Building Made of Precast Slabs?

Whether a 7-story building uses precast slabs depends on specific circumstances and cannot be generalized.

From a historical construction perspective, most 7-story residential buildings constructed 20 years ago used prestressed hollow slabs (i.e., precast slabs) with a brick-concrete structural form. These buildings adhered to the design codes of that time, and precast slabs were widely used in early multi-story residential buildings due to their convenient construction and lower cost.

For currently constructed 7-story buildings, the choice of floor slab types is more flexible. Cast-in-place floor slabs have gradually become the mainstream choice due to their good integrity and strong seismic performance, especially suitable for frame structures or shear wall structural systems. Precast floor slabs (such as prestressed hollow slabs and composite slabs) may still be used, but they must meet current code requirements, for example, by strengthening connection joints and adding structural columns to enhance structural safety.

Regional policies have a significant impact on the use of precast slabs. Some regions, out of safety considerations, have explicitly restricted or prohibited the use of traditional precast slabs in buildings of 7 stories or more. For example, in high-intensity earthquake zones or areas with high requirements for building durability, there is a greater tendency to use cast-in-place floor slabs or new prefabricated floor slab systems (such as steel bar truss floor decking) to reduce structural weak points.

In addition, the intended use of the building also affects the choice of floor slab type. Residential buildings have higher requirements for the integrity of floor slabs to meet living safety needs, while industrial plants or warehouses with lower stories and lighter loads may still use precast slabs to reduce costs.

Summary: Determining whether a 7-story building uses precast slabs requires considering factors such as the construction era, structural form, regional codes, and building use. In modern construction, the proportion of cast-in-place floor slabs is gradually increasing, but precast slabs still have application space under specific conditions, with the key being whether they comply with current safety standards.