Waterproofing and Damp-Proofing for Prefabricated Houses

Waterproofing and damp-proofing for prefabricated houses can be achieved through targeted measures, combining waterproofing and damp-proofing techniques, and addressing materials, structure, and construction comprehensively.

Waterproofing Measures

1. Roof Waterproofing

   • Coating Waterproofing: Small prefabricated houses can apply waterproof coatings such as polyurethane or acrylic on the roof to form a continuous waterproof layer, preventing rainwater penetration.
   • Membrane Waterproofing: For large prefabricated houses, it is recommended to lay waterproof membranes (such as SBS modified bitumen membranes), using specialized adhesives to bond the seams, ensuring durability and stable waterproofing performance.
   • Combination of Thermal Insulation and Waterproofing: Laying thermal insulation materials (such as extruded polystyrene boards) on the roof can not only reduce indoor temperature but also minimize condensation formation by isolating air movement, indirectly aiding waterproofing.

2. Joint Sealing
   During the assembly of prefabricated components, joints should be filled with specialized materials such as silicone sealant or polyurethane foam to ensure tight sealing and prevent rainwater or moisture from infiltrating through the connections.

Damp-Proofing Measures

1. Damp-Proof Membrane Installation

   • Foundation Damp-Proofing: After backfilling and compacting the foundation, lay a layer of fine sand and gravel for leveling, then cover with a high-density polyethylene film (thickness ≥ 0.15 mm). The film should overlap by at least 15 cm and be sealed with waterproof tape. The film should extend up the wall by at least 10 cm before pouring the concrete垫层 (sub-base).
   • Wall Damp-Proofing: Install damp-proof membranes inside or on the surface of walls to block the upward path of ground moisture, taking care to avoid puncturing the film with sharp objects.

2. Elevated Floor Design
   Reserve a 30-50 cm cavity between the foundation and the first-floor ground. Ground moisture rises into the cavity and dissipates naturally, unable to reach the floor, suitable for humid areas or locations with high groundwater levels.

3. Material Modification

   • Add damp-proofing agents (such as calcium stearate) to cement to increase material density and reduce porosity.
   • Use waterproof cement, polymer-modified mortar, and other moisture-resistant materials to enhance the structure's inherent damp-proofing capabilities.

4. Ventilation Optimization

   • Emphasize natural ventilation in the overall layout to prevent moisture accumulation.
   • Install vents in underground spaces and equip them with mechanical ventilation devices (such as exhaust fans) to accelerate moisture removal.

5. Surface Coating Protection
   Apply waterproof paints, epoxy resins, or water-repellent agents to the surfaces of walls and roofs to form a dense protective layer, blocking moisture penetration and extending material lifespan.

Implementation Points: Before construction, assess local climate and geological conditions to select appropriate solutions; ensure material quality meets standards (such as damp-proof membrane thickness, membrane weather resistance); strictly supervise sealing treatments and joint details during construction to ensure the long-term effectiveness of the waterproofing and damp-proofing system.