Leveling Layer of the Roof of a Prefabricated Slab Factory Building

The leveling layer of the roof of a prefabricated slab factory building must be strictly controlled in five aspects: slot cutting control, structural reinforcement, error handling, construction specifications, and concealed works. The specific precautions are as follows:

1. Slot Cutting Depth Limitation

If slot cutting is required, the depth must be strictly controlled to avoid damaging the floor slab structure. The slot cutting depth shall not exceed 20mm or one-fourth of the slab thickness, with an actual operational limit of 3-4cm to prevent cutting through the internal steel reinforcement mesh of the floor slab. The slot cutting direction should avoid horizontal cutting along load-bearing walls, and intersecting slots should be connected at a 45-degree angle to reduce stress concentration. Immediate waterproofing treatment is required after slot cutting, such as using waterstop tapes and expansive waterstop strips to seal the gaps, and retaining concealed work evidence such as 3D scanning reports to ensure traceability for subsequent maintenance.

2. Structural Reinforcement and Leveling Scheme Selection

If the prefabricated slabs have issues such as steel reinforcement aging or increased elasticity due to excessive span, direct leveling may cause shaking, cracks, or even collapse risks. Before construction, a professional team must assess the structural safety to confirm the presence of cracks, settlement, or steel reinforcement corrosion. If reinforcement is needed, steel-reinforced concrete small beams or steel beams can be used for support reinforcement to enhance the floor slab's load-bearing capacity.

The leveling scheme should be selected based on the actual situation:

• Cement Mortar Leveling: Lay in layers, with each layer not exceeding 5cm in thickness. The total thickness should be completed in two layers, and steel wire mesh should be added within the leveling layer to enhance bonding strength and prevent cracking.
• Ceramsite + Steel Wire Mesh + Cement Mortar Combination: Use lightweight ceramsite to replace part of the cement mortar to reduce the floor slab's load-bearing capacity, but professional team construction is required to avoid hollowing.
• Self-Leveling Leveling: Suitable for local elevation adjustments, but elevations exceeding ten centimeters require layered construction, and the prefabricated slab's load-bearing capacity must be confirmed in advance to avoid overloading.

3. Error Handling and Cost Optimization

Roof flatness errors should be handled by category:

• Errors less than 5 millimeters: Can be leveled with gypsum, with a thickness not exceeding 3 millimeters, costing approximately 30 yuan per square meter, suitable for small-scale repairs.
• Errors between 5-20 millimeters or exceeding 20 millimeters: Require resolution through suspended ceilings to avoid cracking and peeling caused by direct leveling. Suspended ceilings can hide errors while reducing the floor slab's load.

4. Construction Specifications and Detail Control

Structural reinforcement must be completed before implementing the leveling layer construction. Expansion joints must be reserved when laying wooden floors to prevent floor arching caused by floor slab deformation. The leveling layer requires curing for more than 7 days after construction to ensure strength compliance. If self-leveling is used, the ambient humidity must be controlled below 50% to prevent bubble formation.

5. Concealed Works and Long-Term Maintenance

Image data and 3D scanning reports for concealed works such as slot cutting and reinforcement must be retained for later inspection and maintenance. After construction completion, regularly inspect the roof status, focusing on reinforced areas and the edges of the leveling layer. Immediate treatment is required if cracks or settlement are detected.