Cracks on Prefabricated House Roof

Cracks on the roof of a prefabricated house can be caused by various factors, and it is necessary to assess the degree of danger and take corresponding measures based on the specific situation.

Causes of Cracks

1. Concrete Shrinkage Issues: In rural self-built houses, if the prefabricated cast-in-place roof is not watered and maintained in a timely manner after being poured in hot weather, the internal moisture of the concrete will quickly dissipate, trapping air bubbles inside. Over time, these can expand and form cracks. This is due to the rapid shrinkage of the concrete.
2. Reinforcement Placement Issues: If the reinforcement is not placed properly, such as adding reinforcement haphazardly and altering the overall tensile force, it can cause uneven stress on the roof of the prefabricated house, leading to cracks.
3. Construction Process Issues: Prefabricated houses using specific construction processes may also develop cracks. For example, when using the 3D steel truss floor panel prefabricated construction process, cracks may appear at the joints of the prefabricated bottom formwork panels. This is because stress changes occur at the joints of the bottom formwork panels, and the bonding strength between the panels does not meet expectations. However, in such cases, the safety of the main structure of the house is usually not affected.

Assessment of the Degree of Danger of Cracks

According to the "Technical Guidelines for the Safety Inspection of Self-built House Structures," cracks in prefabricated panels exceeding 1 millimeter require vigilance. If the crack is located in a load-bearing area, such as a horizontal crack that appears when the roof sags, even if it is only 0.8 millimeters, attention should be paid as it may affect the structural safety of the house. If the crack extends from the roof to two-thirds of the height of the wall or is exactly on a load-bearing beam, the danger factor will double, and in such cases, it must be taken very seriously. If the crack continues to lengthen and widen, even if it has not reached 1 millimeter, a professional organization should be consulted to identify problems in a timely manner and take measures.

Recommended Measures

For cracks on the roof of a prefabricated house, corresponding measures should be taken based on their causes and the degree of danger. If the cracks are caused by concrete shrinkage or reinforcement placement issues and the degree of danger is low, repair and reinforcement can be considered. If the cracks are caused by construction process issues and do not affect the safety of the main structure of the house, their changes can be closely observed. If the degree of danger of the cracks is high, a professional organization should be contacted in a timely manner for testing and assessment, and corresponding treatment measures should be taken based on the assessment results.