PPGI vs PPGL Coil: Key Differences, Cost, and How to Choose (2026 Guide)

Wuxi, Jiangsu Dec 28, 2025 (Issuewire.com) - When comparing PPGI vs PPGL, the main difference lies in the substrate. PPGI uses Galvanized Iron (Zinc coating), while PPGL uses Galvalume (55% Aluminum-Zinc coating).
While they look identical from the outside, the substrate determines their service life and corrosion mechanism.

Quick Answer: Difference between PPGI and PPGLChoose PPGI (Prepainted Galvanized) when: You need a cost-effective solution for general roofing, wall cladding in non-corrosive environments, or interior applications. It offers cathodic protection for cut edges.Choose PPGL (Prepainted Galvalume) when: You are building in coastal, industrial, or high-heat environments. The Aluminum-Zinc alloy offers 2-4x better corrosion resistance than GI.
Structure Difference: Zinc vs Al-ZnBefore comparing performance, clarify the base metal. The lifespan difference comes from what's underneath the paint.
PPGI: Pre-Painted Galvanized Iron. The steel substrate is coated with 100% Zinc.PPGL: Pre-Painted Galvalume (or Aluzinc). The substrate is coated with an alloy of 55% Aluminum, 43.4% Zinc, and 1.6% Silicon.
PPGI vs PPGL Coil: Comparison TableBelow is a detailed breakdown of how the substrate affects performance and buyer choice.
Item PPGI (GI Substrate) PPGL (GL Substrate) Impact on BuyerSubstrate Coating Pure Zinc (Z) 55% Al-Zn Alloy (AZ) Determines corrosion mechanism.Corrosion Resistance Good (Baseline) Excellent (2-4x better) PPGL lasts longer in harsh weather.Weight (Density) Zinc is heavier Al-Zn is lighter PPGL yields 2-3% more meters per ton.Cut-Edge Protection High (Sacrificial) Moderate PPGI is better for intricate cutting.Price Trend Typically Lower Typically Higher Trade-off between budget vs lifespan.For a deeper breakdown, use the PPGI coil price guide.

Service Life ExpectancyHow long will your roof last? It depends on the coating thickness and the environment, but here is the general rule of thumb for standard specifications (Z100 / AZ50):
PPGI Lifespan10 - 15 Years
In normal inland environments. If the Zinc coating is increased to Z275, lifespan can reach 20+ years.
PPGL Lifespan20 - 25+ Years
Offers superior longevity due to the aluminum barrier. In some cases, PPGL can last 2-4 times longer than standard PPGI.
It's Not Just About the Substrate: Paint MattersWhether you choose PPGI or PPGL, the top paint coating plays a crucial role in preventing fading and chalking. Common paint types include:
PE (Polyester):The most common and cost-effective option. Suitable for ordinary residential roofing and indoor use. Warranty: 7-10 years.SMP (Silicone Modified Polyester):Better resistance to UV rays and chalking. Good for areas with strong sunlight. Warranty: 10-15 years.PVDF (Polyvinylidene Fluoride) :The "Gold Standard" for high-end construction. Excellent anti-corrosion and color retention. Highly recommended for PPGL in coastal areas. Warranty: 20+ years.
Why is PPGL price usually higher?The specific Al-Zn alloy technology usually makes PPGL slightly more expensive per ton than PPGI. However, because the Al-Zn coating is less dense than Zinc, one ton of PPGL is slightly longer (more square meters) than one ton of PPGI at the same thickness.
Compare Quotes Like a Pro:Whether you buy PPGI or PPGL, ensure your quote includes: Substrate Type (GI/GL), Coating Mass (Z/AZ), and Paint Thickness. Without these, you cannot compare prices fairly.
Which One to Choose for Your Project?
RoofingCoastal / IndustrialRecommended: PPGL
Salt spray and humidity attack steel fast. The aluminum barrier in PPGL provides superior service life here.
Sandwich PanelsCold Rooms / WallsRecommended: PPGI or PPGL
Both work well. For panels, adhesion and paint flexibility are more critical than the substrate difference.
CladdingGeneral CommercialRecommended: PPGI
For inland commercial buildings, PPGI offers the best balance of cost and performance.
Processing & FormabilityAre you running a roll-forming machine? Here is how they behave during production:

PPGI: Generally has a harder surface but excellent adhesion. It is very forgiving during deep drawing or complex forming.PPGL: The Al-Zn coating is slightly harder and more brittle than pure Zinc. While modern PPGL forms well, micro-cracks can occur on very tight bends if the paint quality is low. Ensure your supplier performs a 0T or 1T Bend Test.
How to Filter a PPGI/PPGL ManufacturerThere are hundreds of pre-painted coil manufacturers. To avoid low-quality material, ask these 3 questions:
1. "Can you provide a coating mass report?" (Ask for Z60-Z275, or AZ30-AZ150).2. "What is your standard T-Bend test result?" (Crucial for preventing paint cracking).3. "Do you allow third-party inspection?" (Reliable suppliers always say yes).
FAQ: PPGI vs PPGL CoilIs PPGL always better than PPGI?Not always. PPGL has better corrosion resistance (2-4x longer life), but PPGI provides better cathodic protection on cut edges and is more cost-effective for dry, inland environments.
What is the lifespan difference between PPGI and PPGL?Under similar conditions, standard PPGI usually lasts 10-15 years, while PPGL can last 20-25 years due to the aluminum content in the coating. High-end PVDF paint can extend this further.
Which paint system should I choose: PE or PVDF?Choose PE for general industrial or residential use (lower cost). Choose PVDF for coastal areas, high-rise buildings, or locations with intense UV radiation, as it offers the best color retention and corrosion resistance.
Can I use PPGI and PPGL together on the same roof?No. Mixing galvanized (Zinc) and Galvalume (Al-Zn) materials can lead to galvanic corrosion where they touch. Stick to one substrate for the entire project.

Is PPGL harder to form than PPGI?The Al-Zn coating is slightly harder than Zinc. For extremely tight bends or deep drawing, PPGI is sometimes preferred. However, high-quality PPGL with a good "T-Bend" rating handles standard roll forming perfectly.