528 Water Protection Day | Overflowing with Knowledge! Building Waterproofing Importance, Leakage Risks, and Prevention Measures

Exterior walls in bathrooms are high-risk zones due to frequent household water usage, leading to moisture accumulation on floors and walls. Over time, this can result in mold growth and peeling paint.

For areas frequently exposed to water such as bathrooms and kitchens, even a single leak can cause water to seep through floor joists and drip down into lower units. This may affect neighbors' daily lives or, in severe cases, lead to major property damage or legal disputes.

Poorly executed waterproofing may lead to leaks later in life, requiring rework. Not only must the original area be excavated and repaired, but the site must also be restored afterward. This not only wastes substantial time and money but also disrupts daily routines.

1) Poor material joint design: No sealing at the joint opening; inadequate use of sealant or tight closure at the joint;

2) Roof tile expansion joints open up, allowing rainwater to penetrate along the wall surface;

3) Cracks in roof tiles or cracks in the foundation soil due to poor backfill compaction.

When the bathroom wall height is low, the roof joint can be directly extended downward to the top of the bathroom wall. Secure it with metal strips and tightly seal with full-coverage waterproof tape. Apply waterproof mortar to the upper part of the expansion joint to prevent water infiltration.

1) Poor drainage slope;

2) Improper installation: gaps not sealed properly, loose fit, no sealing treatment;

3) Incorrect application of waterproof layer and additional layer.

1) Installation location, elevation, and slope must be accurate. Elevation should neither be too high nor too low. Consider factors like drainage slope, leveling layer, insulation layer, and waterproof layer thickness;

2) Install around the perimeter using fine stone concrete (or fiber-reinforced mortar), ensure tight sealing and secure fixation;

3) Within a 500mm radius around the drainage outlet, the slope should be no less than 5%. At the junction between the drain and base layer, leave a 20mm gap and 20mm deep groove. Seal with full-coverage waterproof tape applied twice.

1) Construction does not follow design specifications; improper installation of deformation joints;

2) Sealing materials not properly applied at the interface between precast concrete and expansion joints, or expansion joints open due to improper installation;

3) Metal strip joints open due to poor welding or improper anchoring.

1) Deformation joints must be installed strictly according to design requirements, meeting both deformation and waterproofing needs;

2) Apply proper sealing at each joint of the precast concrete section. Ensure good drainage when installing expansion joints;

3) When using steel plates, ensure side connections are welded or tightly fastened. Where deformation joints meet bathroom walls, the steel plate must be lapped properly.

1) No 20×20mm grooves left between the pipe penetration and the leveling layer;

2) Inadequate application of additional layers; poor workmanship;

3) Roof waterproofing joints not fitted with metal sleeves, leading to aging and cracking.

1) The leveling layer around the pipe penetration should be formed into a circular ridge. Leave a 20×20mm groove between the pipe and the leveling layer, then seal tightly with full-coverage waterproof tape;

2) The additional layers around the pipe must be strictly installed per specifications: two layers total, with half cut into strips to adhere to the base layer, and the other half wrapped around the pipe (over 250mm high). The overlap should be no less than 100mm. The second layer should be placed above the ridge and laid over the pipe with the fabric stretched tight;

3) The roof waterproofing joint must include a metal sleeve, securely tightened and sealed with full-coverage waterproof tape.

1) Thermal stress concentrates at corners, causing greater deformation. The waterproof layer often breaks prematurely compared to flat surfaces, leading to roof leaks;

2) The additional layer does not meet code requirements.

1) The corner area of the waterproof layer should be shaped into a rounded arc or a right angle according to design specifications;

2) Apply an additional layer at the sunny corner, with a width of typically 500mm on either side. Use fully bonded waterproof tape as the main material. Alternatively, use waterproof tape with mesh cloth for reinforcement.

1) Poor waterproofing at the basement top edge leads to floor leakage;

2) Inadequate installation of waterproof materials, poor sealing at corners, improper additional layer shaping, easily causing damage and leakage;

3) Complex foundation structure makes it difficult to achieve precise waterproofing placement, resulting in floor leaks.

1) Use a watertight seal at the basement top edge. Extend the steel bar 50cm into the slab. Apply a 2cm thick waterproof paste around the top edge and 150cm outward. Apply a 2cm thick waterproof paste around the outer edge and 300cm outward. Seal the joint between the pipe and the wall with polyvinyl chloride adhesive tape tightly;

2) Strictly follow specifications during construction. Ensure perfect bonding. After applying the joint and sealing the seam, use a torch or a brush to evenly heat and press the seal tightly, or apply sealing material along the seam with a minimum width of 10mm;

3) Pay special attention to key areas: sump pits, electrical shafts, and corners where floor elevations differ. To ensure waterproofing is properly installed, these areas should be shaped into octagonal shapes. After installing the additional layer and confirming compliance, proceed with large-area waterproofing. The waterproof membrane extending from below the foundation slab can be laid directly onto the permanent wall. Any excess beyond the permanent wall’s protective layer should be covered with a protective film and pressed onto the foundation slab's surface. After completing the foundation work, remove the protective film and apply a polymer-modified cement-based coating directly to the exterior wall of the basement.