Is Waterproofing Required for the Walls of Prefabricated Houses?

The walls of prefabricated houses generally require waterproofing treatment, but due to their structural characteristics, there are certain difficulties and hidden risks in waterproofing. A detailed analysis is as follows:

Inherent Weaknesses in Waterproofing of Prefabricated Houses

Prefabricated houses are assembled on-site from factory-prefabricated components, leaving numerous joints during the assembly process. These joints serve as the main channels for water infiltration, becoming inherent weaknesses in waterproofing. If the joints are not properly treated, water can easily seep into the interior through the gaps, leading to issues such as wall water seepage and mold growth. For example, in old residential areas in Chengdu, due to the high humidity in the basin area and the fact that the joints between the prefabricated floor slabs are natural "water channels", if waterproofing is inadequate, water will spread horizontally through the slab joints to adjacent rooms or even downstairs, causing more severe damage.

Waterproofing Treatment Forms for Joints in Prefabricated Exterior Wall Panels

To address the joint issue, different waterproofing treatment forms are adopted for the exterior wall panels of prefabricated houses:

• Internally-cast and externally-hung prefabricated exterior wall panels (PCF panels): A drainage cavity is set on the outer side and sealed with adhesive, while the inner side relies on the self-waterproofing performance of the cast-in-place concrete. This form is simple and fast in construction, but the waterproofing quality is difficult to control. Blockage of the cavity or cracking of the inner concrete can lead to waterproofing failure.
• Externally-hung prefabricated exterior wall panels: A closed-line waterproofing form is adopted, consisting of three waterproofing measures: high-elasticity weather-resistant waterproof silicone is used on the outermost side, a decompression space formed by a physical cavity is in the middle, and waterproofing is achieved on the inner side by pre-embedded waterproof rubber strips in the concrete that are pressed tightly up and down. In addition, a polyurethane waterproof layer is added outside the rubber waterstop at the cross joints of the wall panels, and drainage pipes are set on the exterior wall waterproof silicone every 3 floors or so to guide the rainwater that has infiltrated the decompression space to the outside.

Importance and Challenges of Waterproofing Treatment

The waterproofing treatment of prefabricated houses needs to balance construction efficiency and long-term effectiveness. For example, the externally-hung prefabricated exterior wall panels effectively reduce the risk of leakage through multiple waterproofing measures and a drainage system, but the construction complexity is high; the internally-cast and externally-hung form is simple in construction but has strict requirements for materials and workmanship. In actual projects, an appropriate waterproofing solution should be selected according to climatic conditions (such as humidity and rainfall) and building purposes, and the joint conditions should be regularly maintained and inspected to ensure long-lasting waterproofing performance.