How to Handle the Roof of Prefabricated Slab Buildings

The handling of the roof of prefabricated slab buildings mainly includes two aspects: waterproofing and crack repair, and appropriate methods should be selected and construction should be carried out in accordance with regulations based on the actual situation.

Waterproofing Treatment

1. Material Selection and Construction Process
Waterproofing is the core part of roof treatment. High-quality waterproof materials such as polyurethane waterproof coatings and SBS modified asphalt waterproof membranes should be selected to ensure that the materials meet the standards for weather resistance and anti-aging performance. The construction process should strictly follow the following steps:

• Base Layer Treatment: Thoroughly clean the roof surface, removing dust, sand, debris, and loose parts to ensure a flat and solid base layer; repair cracks, holes, and other defects with cement mortar, and fill and compact recessed areas in layers.
• Applying Waterproof Coatings: Use the 'cross-coating method' to evenly apply the waterproof coatings, ensuring that the coating thickness is ≥1.5 millimeters, with no missed applications or accumulations; the junction between the wall and the floor should be turned up by more than 30 centimeters to form a continuous waterproof barrier.
• Laying Waterproof Membranes: If membranes are selected, they should be laid from the low to the high areas, with an overlap width of ≥10 centimeters, and the seams should be sealed using the hot-melt or self-adhesive method; additional layers should be laid at details such as internal and external corners and pipe roots.
• Protective Layer Construction: After the waterproof layer passes the inspection, lay a protective layer of cement mortar (thickness ≥2 centimeters) or fine aggregate concrete (thickness ≥4 centimeters) to prevent damage to the waterproof layer from ultraviolet rays and mechanical impacts.

2. Construction Points and Maintenance

• Material Quality: Prioritize the selection of waterproof materials that have passed national inspections to avoid rework caused by the use of inferior products.
• Standardized Operation: The construction environment temperature should be above 5℃, and construction should be avoided on rainy days; the coatings should be applied in 2-3 coats, with an interval of 4-8 hours between each coat.
• Detail Handling: Seal the drainage outlets, exhaust ducts, and other parts tightly with sealant; make rounded corners at the base of the parapet wall to reduce stress concentration.
• Regular Inspection: Inspect the waterproof layer every six months, and repair any cracks or peeling in a timely manner; avoid stacking heavy objects or sharp items on the roof.

Crack Repair

1. Gypsum Board Ceiling Method
Directly suspend a 12-millimeter-thick gypsum board below the prefabricated slab, fix it with light steel keels, and apply putty on the surface of the gypsum board. This method can completely conceal the joints of the prefabricated slabs and avoid cracking problems, but it requires reducing the room height by 5-8 centimeters and has relatively high material and labor costs, making it suitable for scenarios with less strict height requirements.

2. Strengthened Painting Process Method
Stick joint tape at the joints of the prefabricated slabs, then cover with a 10-centimeter-wide layer of fiberglass mesh, and apply putty after covering the entire ceiling with mesh. This method has lower costs (about 30% reduction in costs) and does not occupy height, but it cannot completely eliminate joint cracks and requires regular inspection and reapplication of putty, making it suitable for buildings with limited budgets or height restrictions.