Installation of Prefabricated Slabs for Self-Built House Roofs

The installation of prefabricated slabs for self-built house roofs must strictly adhere to adaptability, operational specifications, and safety requirements. The key points are as follows:

I. Preliminary Adaptation and Material Selection

1. Slope Adaptation: Prefabricated hollow slabs are only suitable for sloped roofs with a gradient of 15°-30°. If the gradient exceeds 30°, components are prone to sliding due to gravity, necessitating the use of alternative structural forms.
2. Material Specifications: Prioritize qualified prefabricated hollow slabs with a thickness of 12-15 cm, ensuring no cracks or deformations on the slab surface. Reinforcing steel must be prestressed, with a concrete strength not lower than C30, and the specifications and quantity of reinforcing steel must comply with national standards.
3. Manufacturer Qualifications: Purchase prefabricated slabs from reputable, large-scale manufacturers to avoid structural safety hazards caused by inferior materials.

II. Installation Operation Key Points

1. Base Layer Treatment: A cement mortar layer over 2 cm thick must be laid on the supporting wall or beam surface to ensure uniform force distribution on the slab bottom and avoid local stress concentration.
2. Fixing Measures:
   • The support length of the prefabricated slab on the wall/beam should be no less than 10 cm at each end (≥120 mm for load-bearing walls, ≥100 mm for non-load-bearing walls).
   • Fix with U-shaped steel clips or tie bars along the slope at intervals not exceeding 80 cm to prevent sliding.
3. Gap Treatment:
   • For gaps between slabs ≤20 mm, fill with fine aggregate concrete; for gaps between 20-50 mm, install a steel mesh before filling to prevent grout leakage or cracking and water seepage.
4. Mortar Seating and Sealing: Mortar should be seated at both ends of the slab, and the holes in the prefabricated slabs at both ends of the wall should be sealed with concrete to prevent rainwater infiltration.

III. Risk Avoidance and Safety Requirements

1. Load Control: Heavy objects are prohibited from being stacked on sloped roofs to prevent deformation of the prefabricated slabs due to overloading.
2. Waterproofing Enhancement:
   • First, lay SBS-type waterproofing membranes on the slab top, then apply a 3-5 cm thick expanded clay concrete protective layer.
   • Alternatively, arrange a steel mesh and pour 6-8 mm thick crushed stone concrete to enhance waterproofing performance.
3. Safety Protection:
   • Implement high-altitude protection measures during installation and prohibit stepping on unfixed prefabricated slabs.
   • Construction personnel must hold relevant certificates or be familiar with high-altitude operation specifications to ensure safe operations.
4. Scenario Limitations: Prefabricated slab sloped roofs are not suitable for large-span (single span > 4 meters) or multi-story self-built houses due to potential structural safety hazards.

IV. Other Precautions

1. Prefabricated floor slabs are prohibited from being arbitrarily cut or slotted and should not be used in damp areas such as kitchens and bathrooms.
2. The lifting sequence should follow the principle of 'inside first, outside later; far first, near later' to avoid additional loads on installed slabs.
3. Before lifting, verify the architectural plan, structural layout plan, and node drawings to ensure that the elevation error of the top surface of load-bearing walls/beams is ≤±5 mm.