Water Leakage in the Interlayer of Prefabricated Slab Houses

The core causes of water leakage in the interlayer of prefabricated slab houses are joint cracking, base layer defects, structural deformation, and material aging, which require comprehensive solutions through crack repair, waterproof layer construction, base layer treatment, and long-term maintenance.

Analysis of Leakage Causes

1. Joint Problems
   Prefabricated slabs are composed of multiple concrete slabs joined together, with the joints filled with rigid materials. Over time, affected by temperature-induced expansion and contraction, building settlement, and roof loads, the joints are prone to cracking and delamination, forming continuous water seepage channels. For example, in northern regions, low winter temperatures cause concrete to contract, while high summer temperatures lead to expansion, gradually rendering the joints ineffective through repeated cycles.

2. Base Layer Defects
   The surface of prefabricated slabs often exhibits unevenness, sanding, peeling, or fine cracks. When the base layer becomes loose and aged, rainwater can flow along the joints or base layer cracks beneath the waterproof layer, causing a mismatch between the leakage point and the actual water seepage location. For instance, accumulated water on the roof may penetrate into the interlayer through base layer cracks rather than directly dripping from the joints.

3. Structural Dynamic Deformation
   Seasonal temperature variations cause thermal expansion and contraction of prefabricated slabs, resulting in frequent dynamic displacement of slab joints. Ordinary waterproof materials (such as thin coatings) lack sufficient tensile strength and are prone to cracking and failure during deformation. For example, in southern regions with large diurnal temperature variations, the waterproof layer may peel off due to repeated stretching.

4. Material Aging
   Subjected to long-term scouring by typhoons and heavy rain, as well as high humidity during the rainy season, the original waterproof layer (such as asphalt felt) is prone to aging and embrittlement, losing its waterproofing function. For example, salt spray corrosion in coastal areas accelerates the performance degradation of waterproof materials.

Treatment Solutions

1. Crack Repair and Reinforcement
   Chisel out a 4-6 cm deep groove along the joint, remove dust and loose concrete, apply a base layer of epoxy resin, fill with epoxy-impregnated hemp fibers, and then fill the joint in layers with a mortar mixture of cement to epoxy resin at a ratio of 3:1, with the surface slightly 1-2 mm higher than the original slab surface to enhance crack resistance.

2. Waterproof Layer Construction
   Select a highly flexible, national standard thick waterproof membrane to cover the entire floor surface, and ensure firm adhesion through hot-melt construction. Reinforce areas such as membrane overlaps and internal/external corners with acrylic ester coatings or fiber cloth to form a continuous waterproof barrier.

3. Base Layer and Gutter Treatment
   Perform精细化 (fine) repair of uneven base layers to ensure flatness and firmness. For gutters, adopt a dedicated waterproofing process suitable for exposure (such as an exposed waterproofing system) to enhance protection against adverse conditions such as standing water and ultraviolet radiation.

4. Long-term Maintenance
   Provide a 5-year formal written warranty, regularly inspect the condition of joints and the waterproof layer, and promptly repair minor damages to extend the lifespan of the waterproofing.

Precautions

Before construction, accurately locate leakage points through water injection tests or infrared thermal imaging to avoid blind operations. Ensure the base layer is clean and dry before construction, and select flexible materials suitable for structural deformation to ensure long-lasting waterproofing effects.