Cracking of the Roof of Cement Prefabricated Houses

The cracking of the roof of cement prefabricated houses is mainly caused by issues with materials, construction, loads, natural factors, and connection points, which may lead to safety hazards, affect aesthetics, and reduce the value of the house, requiring targeted prevention.

Causes of Cracking

1. Material Issues: If low-quality prefabricated panels are selected, their strength, durability, and other properties may not meet requirements, leading to deformation and cracking during use, which in turn causes roof cracking.
2. Construction Process Issues: Non-standard or unprofessional construction operations are common causes. For example, if radiating reinforcement bars are not installed as required at the external corners of cantilevered slabs (each external corner should have 7 bars to handle stress concentration, which must be installed when the slab has a single layer of reinforcement), cracks are likely to appear in the slab.
3. Load Issues: If the load borne by the slab during use is excessive, such as when heavy objects are concentrated on the upper floor, it can cause uneven local stress on the slab, exceeding its load-bearing capacity and leading to cracks.
4. Natural Factor Issues: Powerful external forces generated by geological disasters such as earthquakes can damage the slab structure, causing cracking; temperature changes can also cause the slab to expand and contract, and long-term repeated action may trigger cracks.
5. Connection Point Issues: The seismic performance of modular assembled houses is relatively poor compared to cast-in-place houses. In some projects, to meet assembly rate targets, a "patchwork" approach is used, and improper handling of connection points can easily lead to problems and roof cracking.

Dangers of Cracking

1. Safety Hazards: Cracks can reduce the load-bearing capacity of the slab. If the load-bearing capacity is insufficient, it may lead to slab collapse, threatening the lives of occupants.
2. Aesthetic Impact: Cracks on the slab not only affect hygiene but also reduce the overall aesthetic appeal of the building, creating an unpleasant visual impression.
3. Reduced House Value: Quality issues with the slab directly affect the overall quality of the house, thereby reducing its rental and sales value and causing economic losses to the owner.

Preventive Measures

1. Ensure Material Quality: Select high-quality materials and prioritize using branded materials with guarantees for construction to ensure slab quality from the source.
2. Strengthen Technical Management: Strictly supervise and manage the construction process, requiring skilled workers to carry out construction to ensure compliance with specifications.
3. Reduce Load Issues: Heavy objects on the upper floor should be laid out evenly and stably, avoiding concentrated stacking to reduce the load on the slab and prevent cracking due to excessive stress.
4. Strengthen Maintenance and Repair: When cracks appear, timely maintenance and repair should be carried out to prevent further expansion of the cracks and minimize risk factors.