How to Prefabricate House Foundation

The construction of a prefabricated house foundation requires strict adherence to steps to ensure structural safety and durability. The specific process is as follows:

1. Excavation of the foundation pit
Determine the foundation position according to the design drawings and excavate the foundation pit using machinery or manual labor. The depth should be at least 2 meters, and the dimensional error should be controlled within ±5 centimeters to ensure uniform foundation bearing capacity. After excavation, clean up the debris at the bottom of the pit to prevent loose soil from affecting subsequent construction.

2. Pouring of the concrete cushion
Use a pump to transport concrete and completely fill the bottom of the pit to form a 10-centimeter-thick cushion. The cushion material usually adopts C10 or C15 plain concrete, which has moderate strength and low cost. During pouring, it should be 20 centimeters below the ground level to reserve space for subsequent steel bar erection and formwork installation. After the initial setting of the concrete, cover it for moisture-retaining curing to prevent cracking.

3. Erection and binding of steel bars
After the cushion solidifies, erect the foundation steel bars according to the design requirements. The longitudinal bars and stirrups should be cross-bound, with the stirrups closely fitting the longitudinal bars and fixed with wire ties. At the corners, vertical structural column steel bar frameworks should be added to enhance the overall structural integrity. The specifications, spacing, and quantity of steel bars should be determined through structural calculations. For example, the diameter of the main bars may range from 12 to 25 millimeters, and the spacing of the stirrups may range from 100 to 200 millimeters. Random addition or reduction is strictly prohibited.

4. Formwork erection and fixation
Use wooden boards to process the foundation formwork on site and arrange them closely on both sides of the steel bars to form the pouring space for the foundation beam. The formwork should be reinforced to prevent deformation, such as by setting cross braces or diagonal braces on the outside of the formwork, to ensure that it does not deform or leak slurry during concrete pouring. The height of the formwork is usually half of the height of the steel bar framework, and a secondary pouring interface should be reserved.

5. Secondary concrete pouring
After the first pouring to the height of the formwork, install the upper-layer formwork before the initial setting of the concrete and then carry out the secondary pouring. The two pourings should be carried out continuously to avoid the formation of cold joints that affect the structural strength. During pouring, use a vibrating rod to fully vibrate to expel air bubbles and ensure that the concrete compactness meets the design requirements.

6. Damp-proofing and thermal insulation treatment
After the foundation framework is completed, apply waterproof adhesive inside and paste high-strength extruded polystyrene foam boards (with a thickness of 5 to 10 centimeters) as the thermal insulation layer. Then, backfill the soil in layers and compact it. Cover the top with a gravel layer (with a thickness of 10 to 15 centimeters) to form a drainage layer and prevent groundwater infiltration. The damp-proofing treatment should extend 30 centimeters above the ground level to ensure long-term dryness.

7. Formation of the steel bar mesh and peripheral pouring
Lay a crisscross steel bar mesh on the top of the foundation with a spacing of 150 to 200 millimeters, bind and fix it to form an overall mesh framework. Erect a 20-centimeter-high formwork framework around it and pour concrete to form the top surface of the foundation. Reserve tie bars at the connection with the subsequent walls to enhance the structural stability.

Construction key points: All materials should comply with national standards, and the concrete strength should be tested through test blocks. The connection of steel bars should adopt welding or mechanical connection to ensure reliable force transmission. The formwork should not be removed until the concrete reaches at least 75% of the design strength to avoid structural damage.