Leakage in the Gaps of House Prefabricated Slabs

Leakage in the gaps of house prefabricated slabs requires professional repair targeting the gaps, as surface treatment alone cannot solve the problem permanently. Here are specific analyses and handling suggestions:

Causes of Leakage and Core Challenges
The joints in prefabricated assembled houses are high-risk areas for leakage, primarily due to structural characteristics and construction defects. Prefabricated slabs are usually manufactured in factories and then assembled on-site. If the joints are not properly waterproofed, or if the gaps widen due to material aging or settlement deformation, water can penetrate into the structure through capillary action or pressure. Especially when the prefabricated slabs have a hollow interior, water may flow along the gaps into the interior, causing concealed leakage. The core challenge lies in the dynamic nature of the gaps: Traditional rigid waterproof materials (such as cement mortar) are prone to cracking due to minor structural displacements, leading to waterproofing failure; while flexible waterproof materials may detach from the substrate if not firmly bonded, resulting in脱落 (peeling off) due to long-term immersion or UV aging.

Key Steps for Professional Repair

1. Substrate Preparation: Thoroughly clean the gaps of debris, loose concrete, and old waterproof layers. Use high-pressure air or water jets to flush until a solid substrate is exposed. If the gap width exceeds 5mm, repair it with epoxy resin mortar or polymer cement mortar to ensure a dense and void-free gap.
2. Waterproof Layer Application: Select flexible waterproof materials with strong adhesion to the substrate and good weather resistance (such as polyurethane waterproof coatings or acrylic waterproof coatings). Apply multiple coats, allowing the first coat to dry and form a film before applying the second coat. Ensure the coating thickness is ≥1.5mm, and extend the edges at least 200mm on both sides to cover potential leakage points.
3. Reinforcement Layer Installation: Lay non-woven fabric or fiberglass mesh as a reinforcement layer on the waterproof layer. Improve tensile strength by cross-laying to prevent coating cracking due to structural deformation.
4. Protective Layer Construction: After the waterproof layer is fully cured, cover it with a cement mortar or fine aggregate concrete protective layer to prevent UV exposure from accelerating material aging and protect the waterproof layer from mechanical damage.

Long-Term Maintenance Suggestions
Regularly inspect the roof drainage system (such as gutters and downspouts) for blockages to avoid long-term pressure on the joints caused by standing water. Perform local repairs or reapply the waterproof layer every 3-5 years, paying special attention to stress-concentrated areas such as eaves and corners. If structural cracks (such as through cracks) exist in the prefabricated slabs, contact a structural engineer to assess the need for reinforcement to eliminate leakage hazards fundamentally.