When installing WPC decking, choosing the correct joist system is just as important as choosing the decking boards. The wrong joist can lead to water damage, deformation, structural failure, or even complete reinstallation.
This guide explains the differences between wood joists and galvanized steel joists, helping homeowners, contractors, and architects make the right choice based on environment, budget, and long-term durability.
1, Wood Joists — When They Work and When They Don’t
Wood joists are often chosen for small residential projects. They can work well in dry climates and areas with low moisture.
✔ Benefits
- Cost-effective for small indoor or dry outdoor spaces
- Easy to handle and install
- Suitable for low-budget decking installations
❌ Limitations
However, for outdoor applications—especially in humid or coastal regions—wood joists come with serious risks:
- Poor moisture resistance
- Prone to mold, rot, and termites
- Require regular maintenance such as repainting with anti-corrosion coatings
- Shorter lifespan compared to WPC decking itself
- Easily deforms under long-term moisture exposure
Conclusion:
Wood joists are only recommended for dry regions or low-budget residential use, and must be treated with strong anti-corrosion coatings.
2, Why Galvanized Steel Joists Are the Preferred Choice for WPC Decking
For most outdoor applications, especially in humid climates, commercial areas, or large projects, galvanized steel joists (particularly hot-dip galvanized steel) are the superior and more durable solution.
Key Advantages of Galvanized Joists
1) Excellent Moisture & Corrosion Resistance
Hot-dip galvanized steel performs exceptionally well in high humidity and challenging environments:
- Ground floors
- Basements
- Coastal areas
- Rooftop decks
- Outdoor commercial walkways
Steel joists won’t rot, mold, or warp — even after years of exposure to rain and moisture.
2) Higher Load-Bearing Strength
Galvanized steel joists provide:
- Strong structural support
- Excellent stability over long spans
- Reliable performance in high-traffic locations
- Better safety for heavy commercial decks
They are ideal for restaurants, hotels, public spaces, and large terraces.
3) Almost Zero Maintenance
Once installed:
- No repainting
- No anti-corrosion coating needed
- No regular repairs
- No deformation issues
The long-term cost is significantly lower than wood joists.
- 1st generation 3D embossed decking
3, Hot-Dip Galvanized vs. Cold-Galvanized Joists — Why It Matters
Not all galvanized joists are the same.
For WPC decking, the recommendation is clear:
⭐ Choose Hot-Dip Galvanized Joists
- Thicker zinc layer
- Strong adhesion
- Superior rust and corrosion resistance
- Long lifespan (ideal for permanent outdoor structures)
⚠ Avoid Cold-Galvanized Joists
- Thin zinc layer
- Peels off easily
- Only suitable for temporary structures
- Not recommended for decking
4. How to Choose the Right Joist for Your Project
✔ For dry climates or low-budget home installations
Use wood joists (must be fully anti-corrosion treated).
✔ For humid environments, commercial spaces, rooftops, public areas, or long-term use
Choose hot-dip galvanized steel joists for the best durability and safety.
This selection method ensures your decking system stays strong, stable, and maintenance-free for many years.
5, WPC Decking Installation Solutions From Linicewood
At Linicewood — a 15-year WPC manufacturing factory, we provide professional outdoor decking installation systems designed for long service life.
Our recommended structure:
- Concrete piers / cement blocks
- Hot-dip galvanized steel joists (double-layer welding structure)
- Second-generation co-extrusion WPC decking
This system ensures:
- Outstanding load-bearing capacity
- Excellent moisture resistance
- Long-term stability
- Beautiful and durable outdoor flooring
6, Why Choose Linicewood?
- 15+ years specialized in WPC manufacturing
- Full installation system support
- Export experience across Europe, North America, Southeast Asia
- High-strength WPC decking suitable for residential & commercial use
- Factory pricing & customization available
Explore more at: www.Linicewpc.com
