How to Design Prefabricated House Slabs

The design of prefabricated house slabs requires consideration of multiple factors. Here are the key design points:

1. Placement Direction Design

The placement direction of prefabricated slabs should be determined based on the span of the house. It is preferable to build horizontally in the direction with the smaller span, as floor slabs primarily bear pressure intensity rather than just pressure. Horizontal placement can disperse the load and enhance compressive strength. In the event of uneven settlement of the foundation, horizontal floor slabs, due to their smaller span, pose a lower risk of structural deformation and offer higher safety. Choosing the wrong span direction may lead to localized stress concentration in the floor slab, causing cracking or fracture.

2. Material Selection and Quality Control

1. Reinforcement and Concrete Standards: Reinforcement must use prestressed steel bars to enhance tensile strength; the concrete strength grade should not be lower than C30 to ensure structural durability.
2. Specification and Quantity Standards: The diameter, spacing, and quantity of reinforcement must strictly comply with national standards to avoid structural failure due to insufficient reinforcement.
3. Appearance Quality Inspection: The surface of prefabricated slabs should be free from cracks, honeycombs, holes, and other defects, which would otherwise reduce structural strength and waterproofing performance. When purchasing, choose products from reputable manufacturers and verify quality certificates.

3. Placement and Installation Requirements

1. Support Length: When placing prefabricated slabs on concrete members (such as ring beams), the support length must not be less than 80mm; when placing on walls, the support length must not be less than 100mm to ensure effective load transfer.
2. Slab Joint Treatment: When installing, leave a gap of 20-40mm between two slabs. After installation, clean debris from the slab joints and vibrate them densely with cement mortar; if the gap is larger, cast concrete in situ and cure it. It is strictly prohibited to fill with bricks, as this can easily lead to leakage or structural loosening.
3. End Treatment: The lower ends of the slabs should be mortared, and the holes at the ends of the slabs in the walls should be filled with concrete to prevent water infiltration and steel bar corrosion.

4. Leakage Prevention and Overall Design

1. Roof Leakage Prevention: If using prefabricated slabs for the roof, it is recommended to first lay a steel mesh and then pour 6-8mm thick crushed stone concrete to enhance impermeability; cast-in-place roofs are preferred for better waterproofing.
2. Space and Decoration Limitations: Prefabricated slab structures impose requirements on spatial layout and decoration style. Interior decoration should be simple, avoiding complex shapes that increase structural load; prefabricated slabs are not suitable for use in damp areas such as kitchens and bathrooms to prevent leakage risks.

5. Usage Prohibitions

After installation, it is prohibited to arbitrarily cut holes or slots in the prefabricated floor slabs, as this can damage the structural integrity and pose safety hazards. If modifications are needed, they must be evaluated and reinforced by professionals.