What Is Galvalume Roofing? Full Guide to Coating, Lifespan & Benefits

A Galvalume roofing sheet is a steel sheet coated with an alloy of 55% aluminum, 43.4% zinc, and 1.6% silicon. It is the most commonly specified roofing material for industrial and commercial buildings in India due to its superior corrosion resistance and heat reflectivity compared to traditional galvanized iron (GI).

What Makes Galvalume Different from GI?

Galvalume combines two protection mechanisms:

Barrier protection: The aluminum in the coating forms a stable oxide layer that physically blocks moisture and oxygen from reaching the steel core.
Sacrificial protection: The zinc content protects exposed cut edges and scratches through galvanic action — the same mechanism that protects GI sheets.

In contrast, GI sheets use only pure zinc coating. The aluminum content in Galvalume makes it significantly more durable in harsh environments.

Key Benefits of Galvalume Roofing

Benefit	Galvalume	GI (Galvanized)
Typical lifespan	20-40 years	10-15 years
Heat reflectivity	Excellent (aluminum content)	Average
Corrosion resistance	Superior	Moderate
Cost per sq ft	₹40-85 (wholesale)	₹35-70 (wholesale)
Cost per year of life	₹1-4/sq ft/year	₹2-7/sq ft/year

Understanding Galvalume Coating Grades

Galvalume coating is specified by its mass in grams per square meter. The most common grades in India:

AZ70: Entry-level coating. Suitable for temporary structures or dry inland areas with low corrosion risk.
AZ100: Standard grade for most industrial applications. Good balance of cost and durability.
AZ150: Recommended minimum for permanent industrial roofs in North India. Provides 20+ year lifespan.
AZ200: Premium grade for coastal areas, chemical plants, and extreme environments.

A study by the International Lead Zinc Research Organization found that AZ150 Galvalume lasts approximately 2.5x longer than AZ100 in industrial environments, making it the most cost-effective grade for permanent structures.

Where Galvalume Performs Best

Galvalume is ideal for:

Industrial factories and warehouses — long spans, high heat reflection reduces cooling costs
Cold storage facilities — when combined with PUF insulation as sandwich panels
Coastal regions — AZ150+ grades resist salt corrosion effectively
Solar-ready roofs — 25-year lifespan matches solar panel payback periods

Galvalume Pricing (2026 Wholesale)

Thickness	AZ70	AZ100	AZ150
0.35mm	₹40-50/sq ft	₹45-55/sq ft	₹50-60/sq ft
0.47mm	₹50-65/sq ft	₹55-70/sq ft	₹60-75/sq ft
0.55mm	₹60-75/sq ft	₹65-80/sq ft	₹70-85/sq ft

Prices fluctuate weekly with steel mill rates. Contact Apex Metals for current pricing.

What This Means for Your Project

For most industrial projects in North India, Galvalume sheets with AZ150 coating and 0.47mm BMT (base metal thickness) offer the best balance of cost and lifespan. The slightly higher upfront cost over GI is recovered within 5-8 years through reduced maintenance and longer service life.

Technical Frequently Asked Questions

What is Galvalume roofing sheet?

Galvalume is a carbon steel sheet coated with an alloy of 55% aluminum, 43.4% zinc, and 1.6% silicon. The aluminum provides barrier protection against corrosion while the zinc provides sacrificial protection at cut edges. It lasts 20-40 years — three to four times longer than traditional galvanized iron (GI) sheets.

Is Galvalume better than GI?

Yes, for most applications. Galvalume lasts 3-4x longer than GI, reflects more heat (reducing cooling costs by up to 15-25%), and performs better in coastal and industrial environments. It costs 5-10% more upfront but delivers significantly lower cost per year of service life.

How long does Galvalume roofing last?

Galvalume roofing sheets typically last 20-40 years depending on coating grade (AZ70, AZ100, AZ150, AZ200), environmental conditions, and installation quality. Higher coating mass (AZ150+) in dry inland areas can exceed 40 years. Coastal environments may see 15-25 years with proper grades.

What does AZ150 mean in Galvalume?

AZ150 refers to the coating mass — 150 grams per square meter (total both sides) of aluminum-zinc alloy. A higher AZ number means more coating, which means longer corrosion protection. For industrial roofs in North India, AZ150 is the recommended minimum for 20+ year lifespan.