Galvanized Steel vs Aluminum-Zinc Coated Steel – Understanding the Difference
Many Pacific Northwest homeowners and contractors ask: “What’s the difference between galvanized and aluminum-zinc coated steel, and which lasts longer?” This guide explains the coatings, how they resist rust, and which option is best for PNW rain, snow, and coastal climates.
📌 Tap each section below for in-depth details
✅ What is Galvanization? – Tap to Expand
Galvanization is the process of coating steel with a layer of protective zinc. Zinc acts as a sacrificial barrier, corroding first to protect the steel underneath. Even if scratched, zinc continues to protect exposed edges through a process called galvanic action.
✔ **Hot-Dip Galvanizing (ASTM A653):** Steel is submerged in molten zinc, creating a tightly bonded, weather-resistant coating.
✔ **Why It Matters in the PNW:** Rain, snow, and constant moisture accelerate steel corrosion. Zinc coatings delay rust far longer than bare steel or painted surfaces.
✔ **What G115 Means:** The “G” rating refers to zinc weight per square foot. – **G115 = ~1.15 oz of zinc per ft² (350 g/m²)** – thicker than standard G60 or G90 coatings.
✅ G115 Galvanized Steel (24-Gauge) – Tap to Expand
Our 24-gauge panels use one of the heaviest galvanized coatings available: G115 hot-dip galvanizing. This makes them ideal for high-exposure areas and heavy-duty applications:
✔ **Rugged corrosion resistance** – designed for PNW wet, coastal, and snowy climates
✔ **Extra-thick zinc coating** – far thicker than common G60 or G90 panels
✔ **Best for:** Roofing, barns, livestock fencing, and rural properties
✔ **Available Lengths:** 8 ft, 10 ft, 12 ft, 14 ft, 16 ft
✅ Aluminum-Zinc Coated Steel (29-Gauge) – Tap to Expand
Aluminum-zinc coatings combine 55% aluminum, 43.5% zinc, and 1.5% silicon. Often referred to as “Galvalume-type,” this alloy provides:
✔ **Outstanding rust resistance** – aluminum slows corrosion, zinc protects scratches
✔ **Heat reflectivity** – reduces solar absorption, great for sheds and carports
✔ **Lightweight & affordable** – a good balance of cost and durability
✔ **Best for:** Garden beds, DIY siding, carports, and general residential projects
✔ **Available Lengths:** 8 ft, 10 ft, 12 ft, 14 ft
📊 Galvanized vs Aluminum-Zinc – Which Should You Choose? – Tap to Expand
| Feature |
G115 Galvanized (24ga) |
Aluminum-Zinc (29ga) |
| Corrosion Resistance |
High – best for wet/rural exposure |
Very High – excellent for rain & coastal air |
| Heat Reflectivity |
Average |
High – cooler surface in direct sun |
| Expected Lifespan |
20–30+ years |
20–40+ years |
| Typical Use |
Roofing, barns, fencing |
Garden beds, siding, sheds |
| Initial Cost |
Moderate |
Lower |
PNW Recommendation: ✔ Choose G115 galvanized for farm, barn, or high-exposure rural builds ✔ Choose aluminum-zinc for DIY residential projects or heat-reflective siding
🛠 Installation & Maintenance Tips – Tap to Expand
✔ Use zinc-compatible screws or fasteners to prevent galvanic corrosion
✔ Separate from pressure-treated lumber with a barrier
✔ Touch up exposed cuts with a metal-approved sealant
✔ Keep gutters and drainage clear to reduce standing water
⚖ Legal & Safety Notes – Tap to Expand
✔ Panels are commonly used in agricultural and garden projects but are not certified as food-grade
✔ Buyer is responsible for ensuring compliance with local building codes
✔ No implied warranties for specific lifespan or use
✔ “Galvalume” is a registered trademark of BIEC International Inc.; Valley Outdoor Supply is not affiliated with or endorsed by BIEC
📞 Call 360-916-8312 to discuss which panel is right for your Pacific Northwest project!
