Do Prefabricated Houses Require Foundation Excavation?

Whether a prefabricated house requires foundation excavation depends on the specific circumstances and is not an absolute necessity or non-necessity. Here is a detailed analysis:

1. Light and Small Prefabricated Components: No Traditional Foundation Needed, but Basic Treatment Required
If the prefabricated components are small in size and light in weight (such as single-story prefabricated panel houses and temporary buildings), traditional foundation excavation is usually not necessary. However, a thick layer of sand, gravel, or concrete cushion needs to be laid on the foundation surface, with a thickness generally controlled at 10-20 centimeters. The function of the cushion is to disperse the load, adjust the ground flatness, and prevent deformation of the prefabricated components due to ground settlement. For example, some lightweight prefabricated villas use adjustable supports, which are directly installed on the cushion, and the height of the supports compensates for minor ground undulations.

2. Large and Heavy Prefabricated Components: Foundation Excavation and Reinforcement Are Essential
When the prefabricated components are large in volume and significant in weight (such as multi-story prefabricated buildings and prefabricated beams and columns in industrial plants), foundation excavation is necessary to ensure structural safety. The depth of the foundation needs to be determined according to the geological conditions:

• Soft Soil Foundation: It needs to be excavated to the hard soil layer or rock layer, with a depth that may reach 3-5 meters, or even the use of pile foundations (such as concrete cast-in-place piles) to penetrate the soft soil layer;
• Hard Foundation: The depth can be appropriately reduced, but it is necessary to ensure that the foundation bearing capacity meets the design requirements.
  The width of the foundation is usually 0.2-0.5 meters wider than the projected width of the prefabricated components. For example, the recommended foundation width for a three-story prefabricated panel building is 1-1.2 meters to provide sufficient lateral stability. In addition, the bottom of the foundation needs to be compacted and a reinforced concrete base plate laid, with a thickness generally not less than 20 centimeters to enhance overall rigidity.

3. Composite Treatment in Special Scenarios
In earthquake-prone areas or regions with complex geology, even if the prefabricated components are light, foundation reinforcement techniques may need to be combined. For example, rubber isolation bearings or friction pendulum bearings can be used to reduce the impact on the prefabricated structure by isolating seismic energy; or sand and gravel cushions and geogrids can be set in the foundation to improve its seismic performance.

Summary: The foundation treatment of prefabricated houses requires a comprehensive assessment of factors such as component weight, geological conditions, and usage scenarios. Light and small components can simplify basic treatment, but heavy or multi-story structures must strictly follow the specifications for foundation excavation to ensure long-term safety and stability.