What to Do If the Gap in a Prefabricated House Is Too Large

The treatment for large gaps in a prefabricated house should be selected based on the gap size and specific circumstances. Common treatment methods are as follows:

1. Adjust the width of the panel joints
If the gap is caused by installation deviations, the gap difference can be controlled through reasonable panel arrangement during the construction phase. Design specifications typically require the panel joint width to be ≤30mm. By optimizing the arrangement order of the prefabricated panels and adjusting the splicing positions, gaps caused by dimensional deviations can be avoided. This method is suitable for gaps that have not yet formed or are in the early stages of installation, and it is necessary to strictly follow the panel arrangement rules in the design drawings.

2. Fill with fine aggregate concrete
For gaps with a relatively small difference (20-40mm), fine aggregate concrete with a strength grade of C20 or above can be used for filling. Before filling, debris in the gap should be cleaned out, and the base layer should be moistened. During filling, it should be vibrated and compacted in layers to avoid voids. If the gap is in a critical load-bearing area (such as the mid-span or support), Φ4-Φ6 steel bars or steel wire mesh can be added to enhance crack resistance, and the spacing between the steel bars should be controlled at 150-200mm.

3. Reinforce with cast-in-place panel strips
When the gap difference is ≥50mm, a cast-in-place concrete panel strip should be added at the panel joint. The width of the panel strip should not be less than 200mm, and its thickness should be the same as that of the original prefabricated panel. Two Φ10-Φ12 longitudinal steel bars should be arranged inside, and stirrups should be placed at a spacing of Φ6@200. During construction, the protective layer on both sides of the gap, each 50mm wide, should be chiseled out to ensure that the roughness of the bonding surface between the new and old concrete meets the requirements. After pouring, it should be cured for more than 14 days.

4. Reinforce with additional steel bars
For through cracks or areas with a large gap difference, reinforcing steel bars can be added at the bottom or top of the panel joint. Typically, Φ6-Φ8 steel bars are used, with a spacing of 150-200mm, and the length should span more than 300mm on both sides of the crack. The steel bars should be reliably connected to the original structure through bar planting or welding, and the depth of bar planting should meet the requirements of the adhesive product (generally ≥15d, where d is the diameter of the steel bar).

5. Handle special cases
If the gap is accompanied by serious structural problems such as subsidence, wall tilting, or fracture of the prefabricated panel, use must be immediately stopped, and a professional structural engineer should be contacted. Such cases may involve underlying problems such as foundation settlement or insufficient component load-bearing capacity. Professional testing (such as static load tests or radar scanning) is required to determine the extent of the damage, and remedial measures such as carbon fiber reinforcement, external prestressing tensioning, or component replacement may be taken.

Precautions: During the treatment process, drilling or slotting on the prefabricated panel is strictly prohibited to avoid damaging the internal prestressed tendons or reinforcement. If a ceiling, lighting fixtures, etc., need to be installed, the hanging rods should be fixed at the joint between two prefabricated panels, avoiding the load-bearing areas inside the panels. All repair materials should be compatible with the material of the original component, and the construction environment temperature should be between 5-35℃.