Steel Structure Floor Deck: Types, Load Capacity & Cost Guide 2026
Complete guide to steel structure floor deck types. Learn about open deck, closed deck, composite floor deck load capacity, span tables, and cost per square meter for 2026.
Floor deck is one of the most critical — yet most overlooked — components of a steel structure building. Whether you're building a multi-story factory, a warehouse with a mezzanine, or a commercial complex, the right floor deck system determines load capacity, construction speed, and long-term durability.
At OldTie Steel Structure, we manufacture and export three types of floor deck for clients across 30+ countries. This guide breaks down each type, their load capacities, span tables, and what you should expect to pay in 2026.
What Is a Steel Structure Floor Deck?
A steel floor deck (also called steel decking, metal decking, or composite deck) is a cold-formed steel sheet used as a permanent formwork and structural component in concrete slab systems. It serves two purposes:
- Permanent formwork: Eliminates the need for traditional timber or plywood formwork, saving labor and material costs.
- Composite reinforcement: Once concrete hardens, the embossed steel deck bonds with the concrete to act as a composite slab, increasing strength and reducing deflection.
Three Main Types of Steel Floor Deck
1. Open Floor Deck (Open Decking)
Open floor deck features ribs with open sides, allowing concrete to flow through and bond directly with the steel. It's the most common type for general construction.
| Specification | Typical Value |
|---|---|
| Steel thickness | 0.8–1.2 mm |
| Rib height | 38–76 mm |
| Rib spacing | 150–300 mm |
| Sheet width | 600–1,000 mm |
| Effective width | 500–915 mm |
Advantages:
- Lower material cost
- Fast installation (no additional reinforcement needed in many cases)
- Good composite action with concrete
- Lower fire resistance compared to closed deck
- May require additional reinforcement for heavy loads
2. Closed Floor Deck (Closed Decking / Flat Bottom Deck)
Closed floor deck has a flat bottom with enclosed ribs, creating a smooth ceiling surface. This eliminates the need for a separate ceiling finish.
| Specification | Typical Value |
|---|---|
| Steel thickness | 0.9–1.5 mm |
| Rib height | 50–100 mm |
| Effective width | 600–900 mm |
| Bottom surface | Smooth (no exposed ribs) |
Advantages:
- Smooth ceiling finish — no additional plasterboard needed
- Better fire resistance (enclosed ribs act as fire barriers)
- Higher load capacity for the same steel thickness
- Excellent for acoustic treatment
- 15–25% higher material cost than open deck
- Slightly heavier per square meter
3. Composite Floor Deck (Deep Profile Deck)
Composite floor deck is a deep-ribbed profile designed specifically for maximum composite action with concrete. The embossments and interlocking ribs create a mechanical bond that makes the steel and concrete act as a single unit.
| Specification | Typical Value |
|---|---|
| Steel thickness | 0.9–1.5 mm |
| Rib height | 50–200 mm |
| Effective width | 600–900 mm |
| Concrete thickness | 120–250 mm |
Advantages:
- Highest load capacity per unit weight
- Longest spans without temporary propping
- Reduces overall steel weight of the building frame
- Can support point loads up to 10+ tons per square meter
- Requires thicker concrete topping (higher concrete cost)
- Longer curing time before loading
Floor Deck Load Capacity & Span Tables
Understanding load capacity is critical for selecting the right floor deck. Below are typical span tables for uniformly distributed loads.
Open Floor Deck Span Table (1.0 mm thickness, Q235 steel)
| Concrete Slab Thickness | Load Capacity (kN/m²) | Max Span (m) | Deflection Limit |
|---|---|---|---|
| 120 mm | 3.0 | 2.8 | L/250 |
| 120 mm | 5.0 | 2.2 | L/250 |
| 150 mm | 3.0 | 3.2 | L/250 |
| 150 mm | 5.0 | 2.6 | L/250 |
| 200 mm | 3.0 | 3.8 | L/250 |
| 200 mm | 5.0 | 3.0 | L/250 |
Closed Floor Deck Span Table (1.0 mm thickness, Q235 steel)
| Concrete Slab Thickness | Load Capacity (kN/m²) | Max Span (m) | Deflection Limit |
|---|---|---|---|
| 120 mm | 3.0 | 3.0 | L/250 |
| 120 mm | 5.0 | 2.4 | L/250 |
| 150 mm | 3.0 | 3.4 | L/250 |
| 150 mm | 5.0 | 2.8 | L/250 |
| 200 mm | 3.0 | 4.0 | L/250 |
| 200 mm | 5.0 | 3.2 | L/250 |
Composite Floor Deck Span Table (1.2 mm thickness, Q355 steel)
| Concrete Slab Thickness | Load Capacity (kN/m²) | Max Span (m) | Deflection Limit |
|---|---|---|---|
| 150 mm | 5.0 | 3.5 | L/250 |
| 150 mm | 7.5 | 2.8 | L/250 |
| 200 mm | 5.0 | 4.2 | L/250 |
| 200 mm | 10.0 | 3.2 | L/250 |
| 250 mm | 10.0 | 4.0 | L/250 |
| 250 mm | 15.0 | 3.2 | L/250 |
Floor Deck Cost Per Square Meter (2026)
Floor deck costs vary by type, steel grade, thickness, and order volume. Below are FOB China prices for reference.
| Floor Deck Type | Steel Thickness | Cost (USD/m²) | Notes |
|---|---|---|---|
| Open deck | 0.8 mm | $4.50–6.00 | Standard warehouse floors |
| Open deck | 1.0 mm | $5.50–7.50 | Medium-duty mezzanine |
| Open deck | 1.2 mm | $7.00–9.00 | Heavy industrial floors |
| Closed deck | 0.9 mm | $6.50–8.50 | Office/showroom ceilings |
| Closed deck | 1.2 mm | $8.50–11.00 | High-load applications |
| Composite deck | 0.9 mm | $7.00–9.50 | Long-span applications |
| Composite deck | 1.2 mm | $9.00–12.00 | Heavy industrial floors |
Complete Slab Cost (Deck + Concrete + Reinforcement)
For a complete composite floor slab system, you need to add:
| Component | Cost (USD/m²) |
|---|---|
| Steel floor deck | $5.00–12.00 |
| Concrete (C30, 150mm) | $15.00–22.00 |
| Reinforcement mesh | $3.00–5.00 |
| Installation labor | $4.00–8.00 |
| Total slab cost | $27.00–47.00 |
How to Choose the Right Floor Deck
Use this decision matrix to select the best floor deck for your project:
| Application | Recommended Deck | Concrete Thickness | Span |
|---|---|---|---|
| Warehouse mezzanine (light storage) | Open deck, 0.8 mm | 120 mm | 2.0–2.5 m |
| Factory floor (machinery) | Open deck, 1.0 mm | 150 mm | 2.5–3.0 m |
| Multi-story office | Closed deck, 0.9 mm | 150 mm | 3.0–3.5 m |
| Heavy industrial (cranes, racks) | Composite deck, 1.2 mm | 200 mm | 3.5–4.5 m |
| Parking structure | Composite deck, 1.2 mm | 200 mm | 3.5–4.0 m |
| Clean room / lab | Closed deck, 1.0 mm | 150 mm | 3.0–3.5 m |
Floor Deck Installation Best Practices
- Propping: For spans over 3.0 m, use temporary props at mid-span until concrete reaches 75% strength.
- Shear studs: Composite decks require welded shear studs at 150–300 mm spacing for full composite action.
- Edge closures: Install edge closure angles to prevent concrete spillage and ensure clean edges.
- Vapor barrier: For ground-floor slabs, always install a polyethylene vapor barrier before the concrete pour.
- Curing: Keep concrete moist for 7 days minimum. Do not apply heavy loads until 28-day strength is achieved.
Quality Control Checklist for Floor Deck
When ordering floor deck from a Chinese steel structure supplier, verify:
- [ ] Steel grade and thickness match specification (Q235 or Q355, verified by MTR)
- [ ] Galvanizing or paint coating meets corrosion protection requirements
- [ ] Embossment pattern provides adequate composite bond strength
- [ ] Sheet dimensions (length, width, rib height) within ±2 mm tolerance
- [ ] Load test certificates available for the specified span and load
- [ ] Delivery schedule aligns with slab construction timeline
Frequently Asked Questions
Q: Can floor deck be used without concrete? A: Yes, but only as a permanent formwork for lightweight applications. For structural load-bearing, concrete topping is required.
Q: What is the fire rating of steel floor deck? A: Bare steel deck has minimal fire resistance. With concrete topping, ratings of 1–2 hours can be achieved. Closed deck with fire protection can reach 3+ hours.
Q: How much does floor deck weigh per square meter? A: 0.8 mm deck ≈ 8–10 kg/m²; 1.2 mm deck ≈ 12–15 kg/m². Total slab weight (deck + concrete) ranges from 250–400 kg/m².
Q: Can floor deck be customized for my span? A: Yes. OldTie manufactures custom-length floor deck up to 12 meters per sheet, with custom rib heights and profiles available on request.
Conclusion
Steel floor deck is a cost-effective, high-performance solution for steel structure buildings. The right choice depends on your load requirements, span, and budget. For most industrial applications, open or composite deck offers the best balance of cost and performance. For commercial or multi-story buildings, closed deck provides superior aesthetics and fire resistance.
Contact OldTie for a free quote → WhatsApp: +86 166-5073-5555
Our engineering team can help you select the optimal floor deck type, provide span calculations, and deliver a complete slab system tailored to your project.
*OldTie Steel Structure — Floor deck manufacturer and steel building supplier. Shangqiu, Henan, China. 5,000 tons/month production capacity. CE & ISO 9001 certified.*
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