Choosing Between Galvalume and Galvanized Steel for Your Next Project

Every contractor or fabricator knows how quickly corrosion can eat into margins. A roof that rusts within a decade, a purlin that pits before handover, or a panel that fails inspection, each one traces back to one choice made at procurement: the coating system on the steel.

Galvanized and galvalume steels dominate most roofing, cladding, and fabrication applications. Both are coated steels; both look similar at first glance. Yet, they behave very differently once exposed to heat, moisture, and airborne salts, the real-world conditions that define South India’s construction environment.

The goal isn’t to pick the “better” coating in theory, but to select the one that meets your exposure, lifecycle, and cost objectives. This blog distills field performance data and manufacturer guidance into practical insights you can act on before releasing your next steel order.

TL;DR (Key Takeaways)

• Environment dictates coating: choose galvanized for low-exposure interiors and galvalume for high-humidity or heat-prone zones.

• Lifecycle cost beats sticker price: Galvalume’s upfront premium offsets multiple repaint cycles over its lifespan.

• Specification discipline matters: verify coating weight, MTC, and compatible fasteners before installation.

• Digital sourcing reduces error: verified supplier data and region-wise pricing simplify procurement and compliance.

Understanding the Two Coating Systems

Both galvanized and galvalume steels exist for one reason: to protect the base metal from corrosion. Though visually similar, they exhibit distinct behaviours under conditions like heat, moisture, and chemical exposure.

Choosing the right one means understanding not only their composition but also how they behave during fabrication and on-site installation.

Galvanized Steel: Dependable but Limited

Galvanized steel is coated with a uniform layer of zinc through the hot-dip process. This zinc layer acts as a sacrificial shield; it corrodes first, protecting the underlying steel.
The mechanism is simple and predictable, which is why galvanized sheets have been the industry’s default for decades.

Typical coating weights such as G60 or G90 indicate the amount of zinc applied per square meter (180–275 g/m²). Higher weights deliver better protection but also add cost.

Where it works best:

• Low-humidity and inland zones

• Structural framing and ducting

• Temporary sheds and equipment enclosures

Watchpoints:

Once the zinc layer depletes at cut edges or joints, rust begins. That’s why galvanized sheets need regular repainting or sealing in open exposure.

It’s a dependable coating for general use, but not ideal for long-term or coastal applications.

Galvalume Steel: A Longer-Lasting Hybrid

Galvalume steel uses a mix of 55% aluminium, 43.5% zinc, and 1.5% silicon. Here, aluminium forms a dense oxide barrier that resists oxygen and moisture penetration, while zinc continues to offer sacrificial protection wherever the coating is breached.
The silicon ensures uniform adhesion even during roll forming.

This hybrid chemistry gives galvalume steel a service life roughly 2–4 times longer than standard galvanized steel in most atmospheric conditions.
It also offers a smoother surface, which improves paint uniformity and reduces roller wear during fabrication.

Best suited for:

• Roofing and cladding in high-humidity or coastal zones

• Industrial and logistics roofs, where repainting downtime is expensive

• Projects demanding cleaner aesthetics and consistent finish quality

Key limitation:

The aluminium content makes it slightly less reactive to cut-edge corrosion, so edges and holes should always be sealed or painted during installation.

Fabrication and Finishing Insights

Both coatings perform well in forming and fabrication, but they demand slightly different handling on-site and in workshops.

• Forming and welding

Both materials can be roll-formed and bent without damage, though galvalume’s harder surface requires slightly higher forming pressure. When welding is unavoidable, remove the coating in the weld zone, then touch up the area with zinc-rich paint once cooled to restore corrosion resistance.

• Painting and finishing

Galvanized steel accepts direct painting after degreasing and applying a light etch primer. 

Galvalume, however, must be primed with an epoxy or chromate conversion coating before painting. Skipping this step often causes paint peeling and patch corrosion, a common issue in low-bid installations.

• Fasteners and connections

The coating’s life can be drastically shortened by poor fastener choice. Use zinc- or aluminium-capped fasteners for standard conditions and stainless fasteners with EPDM washers for coastal sites. 

Avoid plain carbon-steel screws; they corrode quickly and cause rust streaks on panels. Never allow galvalume to contact copper or lead flashings, the galvanic reaction will pit the aluminium surface.

• Edge and joint protection

Always seal cut edges, drilled holes, and overlaps with compatible sealants or zinc-rich primers. These small steps prevent oxidation spread and are essential to achieving the full design lifespan of either coating

(Also read: Different Types of Roofing Sheets Explained)

Corrosion Resistance and Expected Service Life

Across field tests and manufacturer warranties:

• Galvanized steel typically lasts 15–20 years in inland or dry zones if maintained.

• Galvalume commonly exceeds 35–40 years, even without repainting, under similar exposure.

In coastal Andhra Pradesh or Kerala, where salt spray and high humidity dominate, galvalume maintains its structural integrity significantly longer. However, it’s not immune to damage. Close proximity to the ocean (within 1 km) can still cause edge oxidation unless coated with marine-grade paint systems.

Conversely, in animal housing or high-ammonia environments, galvanized coatings sometimes perform better because aluminium reacts unfavorably with alkaline vapors.

In short:

• Choose galvanised for indoor or mildly exposed work.

• Choose galvalume for high-humidity, high-heat, or coastal exposure zones.

Thermal and Energy Performance

Galvalume-coated panels reflect more sunlight than standard zinc coatings. Their solar reflectance averages around 70–80%, compared to 55–60% for galvanized surfaces.

That translates to noticeably cooler interiors in metal-roofed warehouses and sheds across Telangana and interior Karnataka, an important performance factor in energy-intensive industrial facilities.

(Also read: How to Prevent Corrosion in Steel)

Choosing by Environment and Exposure

Every coated-steel specification looks good on paper. The real test begins once the sheet or section is exposed to a season of rain, dust, and heat. The right coating depends on where the steel will live, not where it’s purchased.

1. Coastal and High-Humidity Regions

For cities such as Visakhapatnam, Kochi, and Chennai, or any project within 10 – 15 km of the coast:

• Galvalume generally outperforms galvanized because its aluminium barrier slows corrosion caused by salt spray and constant moisture.

• However, within the first kilometre from the sea or lagoon edges, even galvalume begins to show oxidation at cut edges. In these extreme zones, buyers should specify marine-grade paint systems or even switch to aluminium or stainless substrates for critical roofing and cladding.

• Galvanized steel, if used, should be limited to non-exposed framing or temporary site structures.

2. Hot Inland or Urban Industrial Areas

In cities such as Hyderabad, Bengaluru, and Anantapur, heat and airborne industrial pollutants are the primary concerns.

• Galvalume remains the preferred option for large sheds and fabrication units due to its higher solar reflectance and slower paint degradation.

• The energy-saving effect is measurable: uninsulated galvalume roofs can reduce indoor temperatures by 2–3 °C compared with similar galvanized roofs.

• Galvanized still fits ducting, interior partitions, and mezzanine flooring, where exposure is limited.

3. Low-Exposure Interiors and Temporary Applications

For interior workshops, equipment enclosures, and temporary site fencing:

• Galvanized steel offers enough protection at a lower upfront cost.

• Contractors often pair G90 galvanized sheets with a single epoxy topcoat, extending life by another 5–7 years without upgrading to galvalume.

4. Ammonia or Alkaline Environments

Dairies, poultry farms, and fertilizer plants generate ammonia and alkaline condensates that can attack aluminium in galvalume coatings.

• In such facilities, galvanized steel or painted hot-dip zinc coatings perform more predictably.

• Always confirm chemical exposure before specifying aluminium-bearing coatings.

Cost, specification, and supply awareness for contractors

Choosing between galvanized and galvalume steel is not just a technical decision; it’s a financial one. What seems cheaper upfront can cost far more over a project’s lifecycle once repainting, labor, and downtime are factored in.

Upfront vs lifecycle cost

In South Indian markets, galvanized steel generally sells for ₹65–₹70 per kg, while galvalume costs around ₹70–₹75 per kg, depending on coating weight and supplier. 

On paper, galvanized looks more affordable. But its shorter repaint cycle, every 7–10 years, makes it costlier to maintain over two decades. Galvalume’s higher corrosion resistance and longer repaint interval (20+ years) deliver better long-term economics, especially for permanent facilities.

Lifecycle comparison

Factor	Galvanized	Galvalume
Base price (approx.)	₹65–₹70 /kg	₹70–₹75 /kg
Typical repaint cycle	7–10 years	20+ years
Average lifespan	15–20 years	35–40 years
Cost efficiency	Lower initial outlay	Lower total ownership cost

Contractors handling long-term assets, factories, logistics parks, or public infrastructure usually recover Galvalume’s premium within one repaint cycle. For temporary structures, however, galvanized remains a practical, budget-conscious choice.

Specification and verification essentials

Price should never outweigh specification accuracy. Before finalizing an order, always confirm coating weight and supplier certification.

• Verify coating weight which is G90 (275 g/m²) for galvanized or AZ150 (150 g/m²) for galvalume.

• Request the Mill Test Certificate (MTC) for every batch and cross-check the coil tag against it.

• Confirm coating uniformity and zinc/aluminium ratio per IS 277 (galvanized) and IS 15961 (galvalume).

• Inspect packaging and ensure coils are stored off the ground and ventilated. Moisture trapped between sheets can cause white rust before installation.

• Avoid informal supplier abbreviations like “GI” or “GL” without coating data; they often conceal downgraded material.

Regional supply clarity

In South India, both coatings are readily available from major mills such as JSW, Tata Steel, and Vizag Steel.
However, prices vary slightly across Andhra Pradesh, Telangana, and Karnataka, depending on logistics and demand cycles.

At SteelonCall, buyers can view daily, region-specific price differences between coatings (G90 vs AZ150), a feature designed to help contractors plan lifecycle costs before tendering or bulk orders.

Check Live Prices →

Related Read:

1 Ton Steel Price Today in India: Updated Rates and Buyer Guide

Tata Steel vs JSW Steel: A Comparative Analysis

Matching coatings to project types

Every project type demands a balance of cost, performance, and environment-specific durability. The right coated steel should fit not just the budget but also the operational life of the structure.
This quick reference helps contractors and fabricators choose the right material for their most common project categories.

Project type	Recommended coating	Reasoning
Coastal residential roof	Galvalume (AZ150+)	Handles salt spray and humidity with minimal repainting.
Inland warehouse or factory roof	Galvalume	Reflects heat, resists pollutants, and reduces energy load.
Agricultural shed or poultry structure	Galvanized (G90)	Zinc performs better against ammonia and chemical vapors.
Interior ducting and framing	Galvanized	Low exposure areas; economical and easy to paint.
Industrial plant cladding	Galvalume	Withstands high heat and corrosive industrial air.
Temporary site structures and fencing	Galvanized	Low-cost and practical for short service life.

Tip for contractors:
When a project requires both roofing and structural components, using galvalume for outer panels and galvanized for internal framing often delivers the best cost-performance balance. This hybrid approach also simplifies sourcing and logistics.

Procurement Checklist Before You Release the Order

Even the right specification can fail if the buying steps are rushed. A quick verification before placing an order prevents most coating-related issues seen on large construction and fabrication projects. This checklist covers the essentials every contractor or site engineer should confirm before material dispatch.

1. Verify coating type and weight

Always check the coating weight mentioned on supplier documents. Use G90 (275 g/m²) for galvanized and AZ150 (150 g/m²) for galvalume in exposed applications. Lower weights, such as G60 or AZ100, may reduce cost but can cut service life by up to 30%.

2. Match brand and mill certificates

Insist on the Mill Test Certificate (MTC) for every batch. It confirms coating composition, base metal grade, and yield strength. Cross-check the coil number printed on the label with the one on the certificate. Most mismatches happen because of swapped or reused tags.

3. Confirm compatibility with fasteners and sealants

Ask suppliers about the fastener material used with each coating. Zinc- or aluminium-capped fasteners are ideal. Avoid plain carbon-steel screws or incompatible sealants that can trigger galvanic corrosion within months.

4. Plan handling and storage

Coated sheets must be stored off the ground on dry, ventilated supports. Condensation trapped between stacked sheets is the most common cause of white rust. For large deliveries, ensure packaging remains sealed until installation to maintain coating integrity.

5. Evaluate lifecycle cost, not just base price

Coating choice should factor in maintenance cycles, repainting, and downtime, not only initial price. A small premium for galvalume can offset years of repainting and labor in high-exposure projects.

Pro tip for buyers
For projects with tight delivery windows, sourcing through a digital platform like SteelonCall simplifies verification. Contractors can access coating data, MTCs, and live prices in one dashboard, removing manual follow-ups and supplier uncertainty.

SteelonCall Makes Steel Sourcing Simple and Transparent

For contractors and fabricators in Andhra Pradesh, Telangana, and Karnataka, the coated-steel supply chain has evolved rapidly in recent years, driven by digital transparency and verified sourcing.

SteelonCall is at the forefront of this shift. Through its platform, buyers can:

• Compare live regional prices for galvanized and galvalume coils across multiple verified brands.

• Access mill-certified material with coating weights such as G90 and AZ150, reducing the risk of mislabeled stock.

• Place bulk or custom orders for roofing sheets, purlins, and cladding materials directly from manufacturers.

• Track delivery and logistics end-to-end through a unified dashboard.

This digital visibility replaces verbal dealer quotes with traceable, mill-linked data, helping project teams make faster, compliant procurement decisions.
It’s the practical bridge between technical specification and on-site reality, the kind of control today’s construction professionals expect.

(Also read: Understanding Mild Steel Grades in Indian Standards)

Conclusion

Choosing between galvanized and galvalume steel is not just a specification detail. It determines how long a structure stays reliable, how much maintenance it needs, and whether the investment truly delivers value over time.

For builders and fabricators, the right choice depends on where the project stands, the environment it faces, and the service life expected.

By combining that technical understanding with verified sourcing through SteelonCall, every order becomes a confident, data-backed decision that protects both performance and margins.

Plan Your Next Coated Steel Purchase with Confidence
Explore live regional prices for galvanized and galvalume steel, verify coating grades, and order directly from trusted manufacturers.
Check Live Prices →

Frequently Asked Questions

1. Does Galvalume always last longer than galvanized steel?

Yes, in most open-air and humid environments, galvalume offers roughly twice the lifespan of galvanized steel. However, performance depends on coating weight, detailing, and maintenance. In enclosed or ammonia-rich environments, galvanized may still perform better.

2. Can galvalume be used right near the sea?

It performs well in coastal zones but is not ideal within one kilometre of the surf line. In that zone, consider marine-grade painted galvalume or aluminum.

3. Which coating is easier to paint or coat?

Galvanized steel requires minimal surface prep before painting.
Galvalume needs an epoxy or conversion primer to bond properly.

4. How do coating weights like G90 and AZ150 affect durability?

Higher weights mean thicker protection. G90 and AZ150 are standard for exposed construction; lighter coatings like G60 or AZ100 are suitable only for interior or short-life uses.

5. Do fasteners really make a difference?

Absolutely. Using stainless or zinc-aluminium capped fasteners prevents dissimilar-metal corrosion, extending roof life by several years.