Foundation for Small Prefabricated Houses
The selection of foundation types for small prefabricated houses with a two-story brick-concrete structure should consider geological conditions, load requirements, and cost-effectiveness. Common types and their applicable scenarios are as follows:
1. Strip Foundation: The Preferred Choice for Favorable Geological Conditions
Strip foundations involve pouring continuous concrete beams along the direction of the house walls to evenly transfer wall loads to the underlying soil. Their key advantages are simple construction and low cost, making them particularly suitable for areas with stable geological conditions (such as hard plastic clay and sandy soil), low groundwater levels, and small house loads (e.g., two-story brick-concrete structures). In rural self-built houses, strip foundations are the most cost-effective choice due to their low technical threshold and easy access to materials. However, it should be noted that if the foundation has a weak underlying layer or uneven soil distribution, strip foundations may lead to wall cracking due to local settlement, necessitating prior geological exploration to confirm soil uniformity.
2. Pile Foundation: A Solution for Soft Foundations or High Settlement Control Requirements
When the foundation soil quality is poor (such as silt layers or loose fill) or the groundwater level is high, pile foundations transfer loads to deep stable soil layers through driven or bored piles, effectively avoiding settlement issues in the surface soft soil. Bored piles are commonly used in rural self-built houses due to their flexible construction, which allows for adjustments in pile length and diameter based on geological conditions. For example, in coastal areas with silt soil, pile foundations can penetrate the soft soil layer to reach the hard soil layer, ensuring house stability. However, pile foundations are more costly and require professional equipment for construction, making them suitable for buildings sensitive to settlement or with heavy loads.
3. Raft Foundation: The Last Resort for Complex Geological Conditions or Heavy Loads
Raft foundations involve pouring a reinforced concrete slab across the entire bottom of the house to evenly distribute loads over a large foundation area, making them suitable for areas with extremely poor geological conditions (such as miscellaneous fill or karst development zones) or heavy loads (e.g., multi-story residential buildings). For two-story brick-concrete houses, if the foundation bearing capacity is insufficient (e.g., high soil compressibility), raft foundations can reduce local stress concentration and avoid uneven settlement. However, their cost is significantly higher than that of strip foundations, and they require more complex steel bar tying and concrete pouring processes, typically serving as a backup option for harsh geological conditions.
Comprehensive Recommendations: For small prefabricated houses with a two-story brick-concrete structure, if the geological conditions are favorable (e.g., uniform soil layers and high bearing capacity), strip foundations are the optimal choice balancing cost-effectiveness and stability; if the foundation has weak layers or a high groundwater level, pile foundations should be prioritized; only when the foundation conditions are extremely poor and the load is heavy should raft foundations be considered. Before construction, detailed geological exploration must be conducted to determine the foundation type based on the soil report and house design load, avoiding structural safety hazards due to improper foundation selection.
