Leakage in Top-Floor Prefabricated Slab Houses

Leakage in top-floor prefabricated slab houses can be resolved through systematic renovation, covering with color-coated steel roofing, repairing with waterproof membranes, or covering with plastic film, depending on the house's condition, budget, and usage requirements.

Core Causes of Leakage

1. Structural Defects: Prefabricated slabs are assembled structures, with slab joints being the primary channels for water infiltration. Affected by temperature differences, settlement, and loads, slab joints continuously open and close, causing ordinary waterproof layers to crack and delaminate. For example, the Sanxiaokou Qiguitang community in Hefei once experienced water flowing internally through the prefabricated slabs, making complete repair difficult.
2. Substrate Issues: Problems such as uneven surfaces, sanding, peeling, and fine cracks, when soaked by standing water over time, lead to substrate loosening and aging. Water then flows beneath the waterproof layer, creating hidden leakage points that cannot be cured by local repairs.
3. Dynamic Deformation: Prefabricated slabs frequently expand and contract due to temperature changes. Ordinary waterproof materials lack sufficient tensile and deformation resistance, leading to short-term cracking and failure, with a much higher recurrence rate of leakage compared to cast-in-place roofs. Additionally, prefabricated slab materials age rapidly, with a lifespan of about 10 years, after which cracks worsen leakage.
4. Weak Gutters: Accumulation of water, dust, and fallen leaves in roof gutters, combined with long-term exposure to rain and ultraviolet rays, causes conventional waterproofing to age and powder, becoming a high-risk area for leakage.
5. Thin Waterproof Layers: In rural self-built houses, the construction quality of waterproof layers on prefabricated slab roofs is often poor, with 8 out of 10 houses experiencing rain leakage issues that remain unresolved despite multiple repairs.

Solutions

1. Systematic Renovation: Addressing the leakage weaknesses of prefabricated slab structures, this approach employs comprehensive obstacle removal, substrate repair, slab joint reinforcement, national-standard thickened membrane waterproofing, and specialized gutter waterproofing enhancement to resolve issues of dynamic deformation and hidden leakage.
2. Color-Coated Steel Roofing Cover: Covering the entire roof with anti-rust coated metal sheets, available in both pitched and flat installation styles, offers consistent rain protection with a lifespan of up to 20 years and a cost of approximately 60-80 yuan per square meter.
3. Waterproof Membrane Repair: Selecting reliable-quality waterproof membranes, this method relies on the technical skill of installers, with a lifespan of about 15 years. The material cost alone is around a dozen yuan per square meter, but the overall cost is relatively high.
4. Plastic Film Cover: The lowest-cost option (about 2 yuan per square meter), but its effectiveness lasts only 2-3 years. The film needs to be secured with coverings, making it suitable for temporary or low-budget scenarios.