Construction Methods for Prefabricated House Foundations

The construction methods for prefabricated house foundations mainly include site leveling, layout marking, excavation of foundation pits, foundation cushion construction, steel bar binding, formwork erection, and concrete pouring. Additionally, attention should be paid to soil investigation, foundation pit depth and width, soil drainage, and treatment during foundation construction.

1. Site Leveling: Clear stones, weeds, and other debris from the residential site. Fill in any depressions on the ground with soil to provide a level surface for subsequent construction.
2. Layout Marking: Use a measuring tape and white lime powder to measure and mark lines on the ground, accurately determining the position and size of the house foundation to ensure the accuracy of foundation construction.
3. Excavation of Foundation Pits: Excavate along the marked lines using tools such as hoes and shovels. Pay attention to the depth and width during excavation, as requirements vary for different prefabricated houses. Generally, excavate to the hard soil layer or according to the dimensions specified by the construction supervisor. If large stones or other obstacles are encountered, remove them promptly.
4. Foundation Cushion Construction:
   • The formwork for the cushion must be stable and secure to ensure the accuracy of the cushion's shape and dimensions.
   • Pour the mixed concrete into the foundation pit and smooth it with a trowel. Generally, C10 or C15 plain concrete with a thickness of 10 centimeters is used. Its functions include evenly distributing the upper load to the foundation, providing a level working surface for steel bar binding, and isolating soil moisture to prevent steel bar corrosion.
5. Steel Bar Binding: Arrange the steel bars according to the designed layout and bind them with iron wire. The number, diameter, and stirrup spacing of the main steel bars in the ground beam must be calculated and not arbitrarily increased or decreased. The lap length of the steel bars must be sufficient, and spot welding cannot be used instead of binding. Use national standard products to ensure the strength and stability of the steel bars.
6. Formwork Erection and Concrete Pouring: After erecting the formwork, pour concrete into it. Once the concrete sets, the foundation is complete.

In addition, there are some general considerations for foundation construction:

• Soil Investigation: The soil quality of rural residential sites varies greatly and cannot be judged solely by experience. If possible, choose a professional soil investigation agency. To save money, use a Luoyang shovel to dig several points on the residential site to check the soil quality and select an appropriate foundation type based on the results.
• Foundation Pit Depth and Width: Taking a strip foundation as an example, the depth of the foundation pit should be excavated to the hard soil layer. If it is difficult to determine or soil replacement is required, excavate to a depth of at least 1.2 - 1.5 meters. The width of the foundation pit should be at least 0.8 meters; otherwise, the foundation bearing capacity will be insufficient in the later stages, leading to cracks or even tilting of the walls.
• Soil Drainage and Treatment: During construction, it is necessary to drain groundwater from the foundation and prevent water from flowing back. Common methods include open drainage and artificial groundwater level lowering.