Comparing Pre Galvanized Steel G90 Hot-Dip Galvanized and Galvalume for Protected Agriculture

By: Corella Agro Greenhouses

Published On: February 11, 2026

Protected agriculture structures like greenhouses, shade houses, and tunnels require materials that resist corrosion, maintain strength, and offer long service life. Choosing the right steel type can impact durability, maintenance costs, and overall performance. We will compare three popular steel options for protected agriculture: Pre Galvanized Steel (G90), Hot-Dip Galvanized Steel, and Galvalume Steel. Understanding their differences will help you as a growers make informed decisions for their projects.

What Is Pre Galvanized Steel (G90)?

Pre Galvanized Steel, often referred to as G90, is steel coated with zinc before fabrication. The "G90" rating means the steel has a zinc coating weighing 0.90 ounces per square foot, providing a moderate level of corrosion resistance.

Key Features of Pre Galvanized Steel G90

• Manufactured with zinc coating applied in a controlled factory environment

• Coating thickness is uniform but thinner compared to hot-dip galvanizing

• Suitable for indoor or mildly corrosive environments

• Easier to weld and fabricate before coating wears off

• Cost-effective option for structures with limited exposure to harsh weather

  
  

How is it Use in Protected Agriculture?

Pre Galvanized Steel G90 is often used for framing lightweight tunnels or shade structures where exposure to moisture and chemicals is limited. It offers decent protection but may require additional maintenance or painting in humid or coastal areas.

Understanding Hot-Dip Galvanized Steel

Hot-Dip Galvanized Steel undergoes a process where steel is dipped into molten zinc, creating a thick, durable coating that bonds metallurgically with the steel surface.

Characteristics of Hot-Dip Galvanized Steel

• Zinc coating is thicker and more robust than pre galvanized steel

• Provides excellent corrosion resistance, especially in outdoor and harsh environments

• Coating can withstand scratches and minor damage without rusting

• Requires post-fabrication galvanizing or welding repairs to maintain protection

• Typically more expensive due to the intensive coating process

  
  

How is it Applicable in Protected Agriculture?

Hot-Dip Galvanized Steel is ideal for tunnel, greenhouse frames, and shade structures that support exposed to rain, humidity, and fertilizers. Its durability reduces maintenance and extends the lifespan of agricultural growers, especially in coastal or high-rainfall regions.

What Makes Galvalume Steel Different?

Galvalume Steel combines aluminum, zinc, and silicon in its coating, offering a unique blend of corrosion resistance and heat reflectivity.

Features of Galvalume Steel

• Coating typically consists of 55% aluminum, 43.5% zinc, and 1.5% silicon

• Aluminum provides excellent resistance to oxidation and heat

• Zinc offers sacrificial protection against corrosion

• Reflects sunlight, reducing heat buildup in structures

• Coating is smooth and less prone to chalking or rusting over time

  
  

How it Benefits for Protected Agriculture?

Galvalume Steel is often used for roofing and cladding in greenhouses and shade houses. Its reflective surface helps control internal temperatures, improving plant growth conditions. The coating’s durability suits environments with high UV exposure and moderate corrosion risk.

Comparing Corrosion Resistance

Corrosion resistance is a critical factor for steel used in agriculture, where moisture, fertilizers, and chemicals accelerate rust.

Hot-Dip Galvanized Steel generally outperforms Pre Galvanized Steel in corrosion resistance due to its thicker coating. Galvalume Steel offers superior protection against rust and heat, making it a strong choice for roofing and cladding.

Cost Considerations

Budget plays a significant role in material selection. Pre Galvanized Steel G90 is usually the most affordable option, followed by Galvalume Steel, with Hot-Dip Galvanized Steel being the most expensive.

• Pre Galvanized Steel G90: Lower upfront cost, but may require more frequent maintenance or replacement in harsh environments. Varies from G90 creation.

• Hot-Dip Galvanized Steel: Higher initial cost but lower maintenance and longer lifespan.

• Galvalume Steel: Mid-range cost with benefits in heat reflection and corrosion resistance, especially for roofing.

  
  

Practical Examples in Protected Agriculture

• A small-scale vegetable grower in a dry inland region might choose Pre Galvanized Steel G90 for tunnel frames due to cost savings and moderate corrosion risk.

• A commercial tunnel grower near the coast with high humidity and salt exposure would benefit from Hot-Dip Galvanized Steel to ensure structural longevity.

• A large nursery using metal roofing to control temperature and reduce heat stress on plants might select Galvalume Steel for its reflective properties and corrosion resistance.

  
  

Choosing the right steel depends on your specific environment, budget, and structural needs. Take into consideration the exposure to moisture, chemicals, and sunlight when selecting materials. Investing in the appropriate steel type can reduce maintenance, improve plant protection, and extend the life of your agricultural structures.