Prefabricated Slabs for Eaves Overhanging of Self-built Houses
There are many problems with using prefabricated slabs as eaves overhanging slabs or roofing materials for self-built houses. It is not recommended to prioritize their use. If they must be used, risks should be strictly evaluated and remedial measures should be taken.
Poor Seismic Resistance and Structural Safety
Prefabricated slabs are prefabricated components that are usually connected to walls through simple overlapping or local fixation, not a monolithic cast-in-place structure. This connection method is prone to separation under earthquakes or external impacts, leading to the collapse of eaves or roofs. Especially in earthquake-prone areas, if prefabricated slabs are used in parts such as gatehouses and overhanging staircases without column support or proper fixation, the safety hazards are even more prominent.
Prominent Problems of Cracking and Leakage
There are gaps at the joints of prefabricated slabs. Affected by foundation settlement, temperature changes (thermal expansion and contraction), or construction errors, these gaps are likely to expand and form cracks. Rainwater can seep into the interior through the cracks, causing wall mold and decoration damage. Even if waterproof coatings or sealants are used for treatment, they may still fail due to material aging after long-term use, requiring frequent maintenance.
Insufficient Thermal Insulation Performance
Most prefabricated slabs have a hollow structure, with poor heat insulation in summer and heat preservation in winter. In summer, the indoor temperature is easily affected by high external temperatures, and additional air conditioners or fans are required for cooling. In winter, heat is quickly lost through the hollow parts, increasing heating energy consumption. To improve this problem, it is necessary to cover the surface of the prefabricated slabs with thermal insulation layers (such as extruded polystyrene boards) or secondary roofing materials (such as tiles), but this will increase costs and construction complexity.
Applicable Scenarios and Alternative Suggestions
If prefabricated slabs must be used due to economic constraints, the following conditions should be met:
- In non-earthquake-prone areas and with simple building structures (such as single-story bungalows);
- Strictly follow construction specifications to ensure a firm connection between the prefabricated slabs and the walls and proper waterproofing at the joints;
- Accept regular maintenance, regularly check for cracks and repair them, and replace aging waterproof materials.
It is more recommended to use cast-in-place concrete or wooden-framed tile roofs: Cast-in-place concrete has strong integrity, good seismic resistance, and can be designed with thermal insulation layers according to needs. Wooden-framed tile roofs have good air permeability and better thermal insulation performance than prefabricated slabs, suitable for traditional-style buildings. If construction speed is pursued, light steel keel structures can be selected, but attention should be paid to anti-corrosion treatment.
