How to Do Waterproofing for Prefabricated House Roof
Waterproofing for the roof of a prefabricated house can be carried out by referring to the general standard construction methods for roof waterproofing, combined with the characteristics of the materials and regulatory requirements. The core steps include base layer treatment, strengthening of detailed nodes, laying of the waterproof layer, and construction of the protective layer.
1. Base Layer Treatment
The base layer is the foundation of the waterproof layer and must be flat, solid, dry, and free of impurities. First, remove the old waterproof layer, oil stains, dust, and debris from the roof of the prefabricated panels to avoid residues affecting the bonding effect of the new waterproof layer. Next, check the base layer for cracks, holes, or unevenness, and use grinding tools to trim the surface to ensure there are no sharp protrusions or depressions. If there is standing water on the base layer, it must be thoroughly dried before construction; otherwise, it will cause the waterproof layer to bulge or peel off.
2. Strengthening of Detailed Nodes
Cracks, holes, internal and external corners, and pipe roots on the roof of prefabricated panels are high-risk areas for leakage and require special attention. Use leak-stopping compounds or cement-based permeable crystalline waterproofing materials to fill cracks and holes, ensuring dense filling without voids. For internal and external corners, pipe roots, and other turning points, cut waterproof membranes or apply waterproof coatings for additional layer treatment, with a width generally not less than 250mm, to enhance local anti-seepage capabilities.
3. Waterproof Layer Construction
Select appropriate materials based on the building's waterproofing grade and requirements. For buildings with high waterproofing requirements or important structures, it is recommended to use synthetic polymer waterproof membranes (such as polyethylene polypropylene fiber membranes) or polymer-modified bitumen waterproof membranes, which have excellent weather resistance and aging resistance, with a reasonable service life of up to 25 years. During construction, pay attention to the following:
- Membrane laying direction: Lay parallel to the ridge direction, with the long-side lap joints following the direction of water flow and the short-side lap joints staggered by at least 500mm.
- Lap width: The lap width for synthetic polymer membranes should be not less than 80mm, and for polymer-modified bitumen membranes, not less than 100mm. The lap joints should be sealed with special adhesives or hot-melt methods.
- Multi-layer waterproofing: Important buildings should adopt three or more layers of waterproofing, such as first applying a waterproof coating, then laying two layers of waterproof membranes to form a composite waterproof layer.
4. Protective Layer Construction
After the waterproof layer is completed, a protective layer should be promptly laid to prevent UV aging, mechanical damage, or human-induced damage. Protective layer materials can include fine aggregate concrete, cement mortar, or light-colored reflective coatings, with a thickness generally not less than 40mm. During construction, avoid sharp tools from scratching the waterproof layer, and an isolation layer (such as geotextile) should be placed between the protective layer and the waterproof layer to prevent bonding from damaging the waterproof layer.
Tip: Currently, there is no complete construction specification specifically for the roof of prefabricated houses. Actual operations should be combined with the "Technical Code for Roof Engineering" (GB50345) and material instructions, and carried out by professionals to ensure quality.
