Steel for Sandwich Panels
PPGI, PPGL and Prepainted Steel Skins for PU, PIR, EPS and Rockwool Insulated Panels
Everesteel supplies PPGI, PPGL, and prepainted steel skins for PU, PIR, EPS, and rockwool sandwich panels used in industrial buildings, cold storage, cleanrooms, and insulated roof and wall systems. You buy direct from our coating lines in Jiangyin, China — with custom colors, bonding-compatible back coats, sample matching, in-house processing, and export packaging built into the supply.
- PPGI steel for standard insulated wall and roof panel skins
- PPGL steel for hot, humid, and corrosion-sensitive environments
- Bonding-compatible back coats matched to PU, PIR, EPS, and rockwool cores
- PE, SMP, HDP, and PVDF topcoat systems with custom color matching
- Coil, slit coil, and cut-to-length sheet supply for continuous and discontinuous panel lines
Own Factory. Own Coating Lines. Direct Manufacturing Supply.
Everesteel is a vertically integrated prepainted steel manufacturer based in Jiangyin, Jiangsu — one of China’s major steel processing hubs. Every coil of sandwich panel steel that leaves our facility is produced, coated, processed, and packaged in-house, on our own lines, under our own quality system, with 26,000+ tons of annual production capacity supplying buyers in 65+ countries.
You buy direct from the manufacturer, not through a trading intermediary. That means tighter specification control, more consistent batch quality, shorter communication paths, and pricing aligned more closely with actual production conditions.
When you place an order with Everesteel, you deal directly with the team responsible for production and delivery.
26,000+
tons annual production capacity
6,800+
global buyers served
65+
countries supplied worldwide
98.7%
on-time delivery rate
Why Material Selection Matters for Sandwich Panels
Not every panel skin has the same job. The outer face carries different weathering and appearance demands than the inner face, and a PU wall panel behaves differently from a rockwool fire panel or a cold room enclosure. Choosing one specification for both faces usually means overpaying on the hidden side or underspecifying on the exposed one.
That is why most panel manufacturers use different coating structures for the two steel faces of the same panel. Before you select, it helps to weigh five factors:
- Panel position and core type — outer skin, inner skin, and PU, PIR, EPS, or rockwool core
- Coating system — PE, SMP, HDP, or PVDF, chosen by UV, weathering, and lifespan
- Substrate — galvanized (GI) or galvalume (GL), by corrosion environment and forming
- Bonding / back-coat compatibility — reverse-side coating matched to foam or adhesive
- Cost target — premium long-life exterior skin vs. economical concealed inner skin
Get these right, and you match the steel to how each face is actually formed, bonded, and exposed — no delamination on the line, no wasted spend on hidden surfaces.
Recommended Steel Materials by Sandwich Panel Type
Use this table to match PPGI and PPGL to the right panel and face before you request a quote.
| Sandwich Panel Type | Recommended Material | Why It Is Used |
|---|---|---|
| PU / PIR Panels | PPGI / PPGL with bonding-compatible back coat | Strong adhesion to foam cores for continuous or discontinuous lines, with durable exterior coatings |
| EPS Panels | PPGI with PE or SMP | Cost-effective skins for bonded EPS wall, roof, and enclosure panels |
| Rockwool Panels | PPGI / PPGL with verified back coat | Fire-resistant wall and roof systems using adhesive bonding to mineral wool cores |
| Cold Room Panels | PPGL / PPGI, hygienic back coat | Outer and inner skins selected by temperature, humidity, and cleaning requirements |
| Exterior Roof / Wall Panels | PPGL (AZ) with SMP, HDP, or PVDF | Weathering, color retention, and corrosion resistance for exposed building envelopes |
| Interior / Cleanroom Panels | PPGI / anti-corrosion laminated steel | Cleanable, hygienic inner faces for controlled and food-processing environments |
Not sure which fits your line? Send your core type and panel application and our team will recommend a structure before quoting.
PPGI vs PPGL for Sandwich Panels
Choosing between PPGI and PPGL is one of the most common sourcing decisions for sandwich panel buyers. Both are prepainted coated steel products, so the difference comes down to the metallic coating under the paint.
| Factor | PPGI (Prepainted Galvanized) | PPGL (Prepainted Galvalume) |
|---|---|---|
| Metallic coating | Pure zinc (Z40–Z275) | 55% aluminum, 43.4% zinc, 1.6% silicon (AZ40–AZ150) |
| Corrosion resistance | Good, with sacrificial edge protection | 3–6x higher, better heat reflection |
| Best use | Standard EPS, interior, and inland panels | Cold rooms, hot climates, humid and coastal exteriors |
| Forming | Handles most panel-line profiles well | Slightly less suited to very tight forming |
| Paint options | PE, SMP, HDP, PVDF | PE, SMP, HDP, PVDF |
| Cost level | More economical | Higher, longer service life |
Quick selection guide:
- Choose PPGI for standard EPS panels, interior skins, and cost-sensitive inland projects.
- Choose PPGL when the panel faces heat, humidity, cold room condensation, or coastal exposure.
- Choose PVDF-coated PPGL for appearance-critical or seaside exterior panels needing 20+ years of color retention.
- Choose anti-corrosion laminated steel when the inner face needs a hygienic, cleanable surface for cold rooms or cleanrooms.
Coating and Surface Options for Sandwich Panels
Sandwich panel steel can be specified in different coating systems depending on which face it serves and how the panel is exposed. Each option can be matched to your sample or reference before production begins.
PE (Polyester)
An economical, general-purpose coating with a wide color range. PE suits standard panel skins and interior faces where UV exposure is moderate. Typical service life is 10–15 years before repainting.
SMP (Silicone-Modified Polyester)
Polyester modified with silicone resin for better hardness, gloss retention, and weathering than standard PE. SMP is a strong value choice for exterior wall and roof panels that need durability without premium cost.
HDP (High-Durability Polyester)
A step up in exterior color retention and weathering resistance. HDP is selected where an exposed panel needs stronger fade resistance than SMP but does not require full PVDF performance.
PVDF (Kynar 500®)
The premium architectural standard, with exceptional chemical resistance and near-zero chalking for 20+ years. PVDF is recommended for high-UV, coastal, and appearance-critical exterior panels.
Solid Color Exterior
A clean, uniform painted finish in standard RAL colors for large exterior panel surfaces. Solid color is the practical default for industrial buildings where consistent appearance and cost control matter most.
Custom Colors
White, silver, grey, blue, and custom-matched colors can be supplied according to your physical sample, RAL reference, or target panel design. We provide a sample for approval before mass production to help maintain batch consistency.
Typical Sandwich Panel Applications
Processing Capabilities for Sandwich Panel Production
All coating is carried out in-house at our Jiangyin facility, so your material can arrive in the format your panel line actually needs — not just as a master coil.
Slitting
Master coils are slit to the feed width your continuous or discontinuous panel line requires, with clean edges and tight tolerance control.
Cut-to-Length
Material can be supplied as cut-to-length sheet for direct panel fabrication or profiling — stacked, protected, and secured for export.
Back-Coat and Bonding Support
Reverse-side coating can be matched to your PU, PIR, EPS, or rockwool core, with a bonding trial available before bulk supply to confirm adhesion.
Sample Matching
We match color and surface finish to your sample, target finish, or reference standard, and provide an approval sample before bulk production.
OEM Support
We support panel manufacturers with custom colors, bonding-compatible back coats, coil and sheet supply, protective film, export packaging, and repeat-order production.
Get Sandwich Panel Specifications for Your Project
Tell us your core type, panel line, coating system, thickness, width, and supply format. Our technical team will confirm feasibility and prepare a recommended material specification for your review.
Typical Specifications for Sandwich Panel Steel
| Parameter | Typical Range |
|---|---|
| Base material | GI (galvanized), GL (galvalume / aluzinc) |
| Product types | PPGI, PPGL, anti-corrosion laminated steel |
| Thickness | 0.25 mm – 0.80 mm |
| Width | 600 mm – 1,250 mm (slit widths available) |
| Topcoat options | PE, SMP, HDP, PVDF |
| Metallic coating | Zinc Z40–Z275 / Al-Zn AZ40–AZ150 |
| Reverse side | General or bonding-compatible back coat by core type |
| Supply form | Master coil, slit coil, cut-to-length sheet |
| Color | RAL colors or approved physical sample |
| MOQ | Depends on specification and finish |
| OEM support | Yes |
- Specifications are indicative and will be confirmed during the technical review at the time of order.
Quality Control and Certifications
Everesteel operates under a documented quality management system that covers incoming substrate inspection, coating line parameters, surface appearance control, and final product inspection prior to shipment.
Standard quality controls applied to sandwich panel steel include:
- Incoming substrate inspection for thickness, width, surface condition, and base metal conformity
- Zinc and Al-Zn coating weight verification against the specified Z or AZ class
- Paint film thickness (DFT) measured and recorded per batch for top coat and back coat
- Reverse-side coating identification and bonding-compatibility confirmation for the core type
- Color and gloss checked against the approved RAL reference or physical sample
- Coating adhesion testing verified through cross-cut and T-bend checks
- Bonding trial with the actual foam or adhesive system when required before mass production
- Salt spray and weathering exposure checks for exterior and PVDF systems
- Dimensional, flatness, and slit-width verification prior to packaging and shipment
FAQs
Q1. What steel is used for sandwich panels?
Sandwich panels commonly use PPGI and PPGL coated steel skins over PU, PIR, EPS, or rockwool cores. The right choice depends on the core type, whether the face is an exposed outer skin or a concealed inner skin, and the panel’s service environment.
Q2. Can the same steel be used for the outer and inner skins?
Yes, but the two faces often use different coating structures because they do different jobs. The outer skin handles weathering, UV, and appearance, while the inner skin handles bonding, cleaning, and interior exposure. We recommend specifying each face separately.
Q3. How is the reverse-side (back-coat) coating selected?
The back coat is matched to your core, foam chemistry, adhesive, curing temperature, and line speed. Because PU, PIR, EPS, and rockwool systems bond differently, we verify the proposed back coat with a bonding trial before bulk production.
Q4. What is the difference between PPGI and PPGL for panels?
PPGI uses a pure-zinc galvanized base, while PPGL uses a galvalume (aluminum-zinc) base. PPGL offers 3–6 times the corrosion resistance and better heat reflection, so it suits cold rooms, humid, and coastal panels, while PPGI fits standard EPS and inland projects.
Q5. Which coating suits exterior sandwich panels?
It depends on climate and lifespan. PE suits standard budgets and moderate UV, SMP and HDP add weathering resistance, and PVDF is the premium choice for high-UV, coastal, or appearance-critical exterior panels needing 20+ years of color retention.
Q6. Do you supply steel for cold room and cleanroom panels?
Yes. For cold rooms and cleanrooms, we supply PPGL and anti-corrosion laminated steel with hygienic, cleanable inner faces selected for condensation, washdown, and controlled-environment requirements. Confirm your temperature and cleaning conditions so we can match the surface.
Q7. Can slit coils be supplied for continuous panel lines?
Yes. Slit width, coil ID, coil weight, and edge condition can be prepared to match your continuous or discontinuous panel line, according to the signed specification. Provide your line width and coil limits with your inquiry.
Q8. Do you provide OEM support for sandwich panel projects?
Yes. We support panel manufacturers with custom colors, bonding-compatible back coats, coating system selection, slitting, cut-to-length processing, sample matching, bonding trials, and export packaging for repeat-order production.
Related Products for Sandwich Panel Projects
Explore the individual materials behind our sandwich panel supply. Each links to full specifications and coating options.
PPGI Coil & Sheet
PPGL Coil & Sheet
Anti-Corrosion Insulation Laminated Steel
Custom Color Coated Steel
Ready to Source Steel for Sandwich Panels?
Send us your panel type, core material, coating system, thickness, width, and estimated quantity. Our team will recommend the right material — PPGI, PPGL, or anti-corrosion laminated steel — based on your core, bonding, environment, and cost requirements, and respond within one business day.
- Panel type — wall panel, roof panel, cold room, cleanroom, or agricultural / commercial
- Core material — PU, PIR, EPS, or rockwool
- Skin — outer skin, inner skin, or both, with any different requirements per face
- Coating system — PE, SMP, HDP, PVDF, or not sure yet
- Reverse-side / back coat — general or bonding-compatible, with foam or adhesive details
- Color reference — RAL code, sample, or target design
- Thickness and width — in millimeters (state base-metal or finished thickness)
- Panel line — continuous or discontinuous, with coil ID and maximum coil weight
- Quantity — in metric tons or coils, and whether one-time or recurring
- Destination country — for freight and lead time estimation