Why Does Bondek Roofing Often Warp? Here Are the Causes and Solutions

Bondek is known as a modern material for concrete floor or slab casting systems that is practical, strong, and efficient. However, in the field, problems with bondek slabs sometimes occur after installation. This condition can certainly affect the structural strength and the final result of the building. So, what causes this and how can it be resolved?

1. Uneven Installation of Supports (Scaffolding)
One of the main causes of curved bondek slabs is supports that are not installed evenly or are spaced too far apart. As a result, the concrete load during pouring is not properly supported, causing certain sections to sag downward.

Solution:
Ensure the spacing between supports meets technical recommendations (usually 1–1.2 meters) and use strong support materials. Perform level checks before pouring.

2. Bondek Thickness Not Meeting Specifications
Bondek is available in several thicknesses (usually 0.75 mm to 1.0 mm). If the thickness used is too thin for the heavy concrete load, the risk of sagging increases.

Solution:
Use bondek with a thickness appropriate to the structure's needs. For large projects, it is recommended to use a minimum of 0.8 mm thick bondek to ensure greater load-bearing strength.

3. Uneven Casting Process
If the concrete is poured too quickly on one side without being evenly distributed, the temporary load will accumulate in certain areas and cause the bondek to sag.

Solution:
Pour the concrete gradually and evenly over the entire surface. Use a vibrator to ensure optimal concrete density without excessive load in any one area.

4. Poor Bondek Quality
Bondek material with a thin galvanized coating or low-grade steel can also cause the structure to be unable to support the cast load. In the long term, the protective coating will quickly deteriorate and rust easily.

Solution:
Ensure that you purchase bondek from a trusted supplier that provides SNI-standard products with high-quality steel and an even galvanized coating.

5. Lack of Technical Supervision
Small errors during installation, such as loose bondek joints or loose bolts, can cause warping after casting.

Solution:
Always have direct supervision by an expert or experienced foreman during the installation and casting process.

Conclusion
A curved Bondek roof is not only an aesthetic issue, but also has the potential to reduce the strength of the building structure. By paying attention to thickness, material quality, and proper installation techniques, you can avoid this risk.

💡 Use quality Bondek from PT Intisumber Bajasakti (ISBS) — a trusted supplier of steel products and building materials with SNI standards, ready to support your construction project needs.
📞 Phone: 021-66675999
🌐 Web: intisumberbajasakti.com
✉️ Email: info@intisumberbajasakti.com

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