Treatment Solutions for Gaps in Prefabricated Houses

The treatment of gaps in prefabricated houses should be based on the type and severity of the gaps, with targeted solutions selected as follows:

I. Treatment of Gaps Between Prefabricated Panels

1. Prevention during Assembly: Use non-shrink epoxy structural assembly adhesive to fill the panel gaps, which can reduce shrinkage cracks caused by temperature changes.
2. Crack Repair Process:
   • Use a wall planer to plane off the surface plaster to a depth of at least 10 centimeters, chisel out an inverted V-shaped notch, and clean the dust.
   • Apply repair adhesive for leveling, and use an angle grinder to polish uneven areas.
   • Apply carbon fiber impregnating adhesive, then paste carbon fiber cloth, use a scraper to remove air bubbles, and apply modified epoxy impregnating adhesive on the surface.
3. Concrete Filling Solution:
   • When the gap difference is 20-40mm, use fine aggregate concrete with a strength grade of C20 or above for gap filling. If necessary, add reinforcing bars or steel wire mesh.
   • When the gap difference is ≥50mm, add a cast-in-place concrete panel strip with a width of not less than 200mm, and configure longitudinal reinforcing bars inside.
4. Reinforcement with Additional Reinforcing Bars: For through cracks or areas with a large gap difference, add Φ6-Φ8 reinforcing bars at the bottom or top of the panel gaps to improve crack resistance.

II. Treatment of Ceiling Cracks in Prefabricated Panel Buildings

1. Treatment of Structural Cracks:
   • When the crack width is >2mm or it is a through crack, immediately contact a professional organization for structural inspection.
   • After confirming the existence of hidden dangers, have a professional team formulate a reinforcement plan, such as carbon fiber cloth reinforcement, steel plate bonding reinforcement, or adding support structures.
2. Treatment of Non-structural Cracks:
   • Fine cracks within 1mm: Cut a micro-groove with a depth of 1-2mm, remove the floating dust, and apply elastic repair agent twice (with an interval of 2 hours), or fill with polymer repair agent/silicone sealant. After curing, polish and apply the same color latex paint.
   • Medium cracks of 1-5mm: Remove the loose base layer around the crack within a range of 20cm, paste fiber mesh to enhance crack resistance, and repair in two layers (the first layer of strong repair paste ≤3mm, the second layer of elastic putty for leveling). After drying, polish and apply latex paint.
   • Severe cracks >5mm: Remove the damaged part around the crack within a range of 30cm to the structural layer, fill with epoxy resin or high-strength cement-based material, apply a bonding agent, then hang steel wire mesh, and scrape waterproof putty in layers and roll on anti-crack latex paint. If there is water seepage, add a waterproofing agent and apply waterproof coating.

III. Treatment of Horizontal Cracks in Prefabricated Panels of Built Houses

1. Observation Stage: If there are few cracks, the gaps are small, and there is no liquid leakage, repair can be temporarily postponed as it has little impact on structural safety.
2. Repair Process:
   • Chisel open the crack panel gaps, chisel off 5cm of the surface layer on both sides, make the joint surface slope-shaped and chisel the surface and sides of the prefabricated panels, and clean them thoroughly.
   • Brush pure cement mortar (water-cement ratio of 0.4-0.5) in the panel gaps, and pour fine aggregate concrete in two batches (the first batch to half of the panel gap depth, the second batch to 1cm from the panel surface and compact and level it).
   • After repair, cure for 2-3 days, and strictly prohibit treading during this period.

IV. Precautions

1. When dealing with cracks, avoid drilling holes in the prefabricated panels to prevent damaging the load-bearing structure of the floor slab.
2. If ceiling or other construction needs to be carried out on the prefabricated panels, the hanging rods should be installed in the gaps between two prefabricated panels to ensure construction safety.