Why Is Steel Thickness Important for Steel Doors?
One of the most frequently asked questions when choosing a steel door is the steel thickness. This parameter, which directly affects the door's security level, thermal insulation, and longevity, is often overlooked. However, the correct steel thickness determines your door's resistance to forced entry while also preserving aesthetics and functionality.
What Is DKP Steel? Advantages and Disadvantages
DKP (Düz Karbonlu Piyasa) steel is a commonly used material in steel door manufacturing. More economical than cold-rolled steel, DKP steel has good formability. However, it shows lower performance in terms of durability and corrosion resistance. Therefore, the quality of surface coating (paint, powder coating, or foil) is crucial for doors using DKP steel.
What Should Be the Ideal Steel Thickness?
Steel thickness in steel doors typically ranges from 0.6 mm to 1.2 mm. So which one is right for you?
- 0.6-0.8 mm: Preferred in economy segment doors. Adequate for areas with low security risk, but does not provide high protection against forced entry.
- 0.9-1.0 mm: Commonly used thickness in the mid-range. Meets standard security needs, with a good balance of durability and price.
- 1.2 mm and above: Premium segment. Offers the highest security level. Especially recommended for exterior and high-risk areas. However, it increases door weight, requiring appropriate hinges and drive systems.
Note: According to the TS EN 1627 standard, steel thickness is not decisive in security classification; frame structure and locking system are equally important.
Considerations for Frame Structure
Another aspect as important as steel thickness is the internal structure of the frame. A door made of a single piece of steel may not provide sufficient resistance to bending. Therefore:
- Double-layer steel usage: Using separate steel panels for inner and outer surfaces significantly strengthens the frame.
- Rigid filling material: Polyurethane foam, rock wool, or honeycomb fillings provide insulation and increase bending resistance that is not visible.
- Welding points: Continuous welding (rather than spot welding) should be preferred at frame joints. Spot-welded doors may experience separation issues over time.
DKP Steel vs Cold-Rolled Steel: Which Is Better?
Cold-rolled steel (especially DC01 grade) offers higher strength and surface smoothness compared to DKP steel. Its corrosion resistance is also better. However, its cost is higher. If your budget allows, choosing cold-rolled steel will be more advantageous in the long run. DKP steel is a cost-effective and easy-to-process alternative. When making this choice, consider the door's location (interior/exterior), exposure to weather conditions, and security requirements.
Production Techniques and Quality Differences
Even with the same steel thickness, production techniques determine quality. Stresses during bending, welding defects, or weak points can shorten the door's lifespan. In a quality steel door:
- Corner joints should be smooth and weld-free (press bending),
- The steel surface should have no ripples or dents,
- Anti-corrosion coating (phosphating, electrocoating) should be applied.
As Işıldak Çelik Kapı, we use at least 1.0 mm steel thickness and cold-rolled material in all our models. Additionally, we maximize sound and thermal insulation with polyurethane filling inside the frame.
