Small Hole in Prefabricated House
The small holes in prefabricated houses typically serve multiple purposes, including weight reduction, installation positioning, drainage and ventilation, balancing mechanical properties, and reserving future interfaces.
1. Weight Reduction and Cost Savings
Small holes significantly reduce wall weight by decreasing concrete usage. For example, a 600mm×2400mm wall panel can have its weight reduced by 15%-20% after being perforated, directly saving on material costs. Additionally, lighter wall panels reduce transportation and lifting difficulties, further cutting construction expenses. This design is particularly crucial in high-rise buildings or large-scale prefabrication projects, effectively controlling overall costs.
2. Installation Positioning and Construction Convenience
Small holes are often used as lifting or positioning holes, typically with a diameter of 50-80mm. During construction, workers can insert steel bars or tools through the holes to precisely adjust the position of wall panels, ensuring accurate splicing. Some designs also incorporate horizontal steel bars through the holes to form an integrated structure with adjacent wall panels, enhancing seismic resistance. For instance, in prefabricated buildings, positioning holes can quickly align components, shortening construction cycles.
3. Drainage and Ventilation Functions
In humid environments, small holes can expel condensed water from within the wall, preventing long-term water accumulation that could lead to steel bar corrosion. Some designs incorporate breathable membranes within the holes to balance internal and external air pressure, preventing wall damage caused by negative pressure due to temperature differences. For example, such designs are commonly used in rainy southern regions to extend building lifespan.
4. Balancing Mechanical Properties
Hole locations must avoid stress concentration areas, typically being at least 100mm from the edge and spaced at least 300mm apart to prevent weakening the wall's compressive strength. Finite element analysis can optimize hole layouts to maximize the benefits of perforation while ensuring structural safety. For example, when perforating the center of a wall panel, additional steel bars around the hole may be needed to compensate for strength loss.
5. Hidden 'Future Interfaces'
Some small holes are reserved for later pipeline installation or equipment fixation. For example, some prefabricated houses in Japan have threaded sleeves embedded in the holes, allowing users to install brackets or hang heavy objects themselves. This design enhances building flexibility to accommodate different usage needs.
Hole Sealing Recommendations
Whether to seal a hole depends on its location, size, and design requirements. Generally, to enhance structural strength and waterproofing, it is recommended to appropriately seal the holes. For example, holes exposed to the outdoors should be filled with waterproof mortar, while internal pipeline holes can remain open and be fitted with protective sleeves.
