Application selection brief
Coated Steel Selection for Roofing and Cladding
Roof and wall sheet performance depends on a system of choices. The base steel, metallic coating, pretreatment, primer, topcoat, back coat, profile geometry, fasteners, sealants, cut edges, drainage, and storage conditions all affect the result. A useful RFQ keeps those layers visible instead of reducing the order to color and thickness.
Selection inputs
Service conditions to define
- External exposure category, including coastal salt, industrial pollutants, humidity, rainfall, ultraviolet exposure, temperature cycling, and roof pitch.
- Building use and internal condensation risk, including livestock, chemicals, insulation, ventilation, and the possibility of wet contact on the sheet underside.
- Profile span, support spacing, wind and snow actions, foot traffic, drainage, penetrations, and fastener layout as defined by the project designer.
- Transport, site storage, installation sequence, cut-edge handling, and the time coils or bundles may remain wrapped before use.
Failure review
Risks the specification must address
- Premature corrosion can begin at cut edges, scratches, fasteners, overlaps, trapped moisture, or incompatible accessories even when the broad sheet area remains intact.
- Paint chalking, fading, blistering, delamination, or back-side corrosion may result when the coating system is mismatched to ultraviolet, chemical, humidity, or condensation exposure.
- Profile distortion, oil canning, leakage, or fastener distress can follow from unsuitable thickness, profile geometry, support spacing, installation, or thermal movement.
- Wet storage stain and pressure marking can develop when bundles remain damp, poorly ventilated, or tightly wrapped after delivery.
Procurement matrix
Compare the service, material route, and evidence
| Exposure and use | System to review | RFQ evidence |
|---|---|---|
| General inland wall or roof exposure | GI or prepainted GI with project-selected coating mass and paint system | Exposure category, coating designation, paint chemistry, DFT, color, profile, and fasteners |
| Hot, humid, coastal, or persistent wet exposure | GL, prepainted GL, or another reviewed higher-durability system | Salt distance, humidity, cut-edge design, warranty terms if offered, and compatibility review |
| Appearance-critical facade | Prepainted system with controlled color, gloss, texture, and batch planning | RAL or approved sample, color tolerance, gloss, texture, paint supplier data, and elevation quantities |
| Condensation-prone building interior | System with reviewed back coat, ventilation, insulation, and underside exposure plan | Internal environment, condensation model, back coat, liner or membrane, and installation details |
Acceptance package
Standards, inspection, and fabrication
Standards and inspection
- State the substrate and coated-product standard, steel grade, metallic coating designation, dimensions, tolerances, and any profile standard or drawing.
- Specify paint chemistry, top and back colors, dry-film thickness targets, gloss or texture, adhesion or bend tests, and the certificate or inspection report required.
- Define sampling, coating-mass verification, paint-thickness measurement, color acceptance, profile dimensions, surface defects, and packaging inspection.
- Confirm that any warranty language comes from the responsible coating-system provider and matches the environment, installation, maintenance, and exclusions.
Fabrication controls
- Agree minimum bend radius, roll-forming direction, profile drawing, embossing or texture, cut method, protective film, and rules for touch-up or damaged areas.
- Review fastener, washer, flashing, sealant, gutter, and dissimilar-metal compatibility as part of the building envelope specification.
- Separate structural sheet design from material supply. Thickness, yield strength, profile, support spacing, and connection design must follow the project calculation.
Continue with the registered product owners
Corrugated galvanized color roof sheet
Review a profiled roof-sheet owner and its purchasing fields.
Open ownerPPGI and PPGL color coated steel coil
Review the prepainted coil owner used before roll forming.
Open ownerRAL color reference
Prepare a color discussion while keeping sample and paint-system controls visible.
Open ownerRoofing profile reference
Compare common profile geometry inputs before issuing a drawing-controlled RFQ.
Open ownerOrder-ready data
RFQ requirements
Send these fields together so technical review starts from one consistent specification.
Prepare an RFQ- 01
Building location, coastal distance, environment, roof or wall use, and internal condensation conditions
- 02
Substrate standard and grade, metallic coating, paint chemistry, top and back DFT, color, gloss, and texture
- 03
Thickness, width, profile drawing, cover width, length, tolerances, and quantity by elevation or batch
- 04
Fastener and accessory compatibility, protective film, cut-edge or touch-up requirements, and inspection plan
- 05
Package limits, unloading method, destination, site storage plan, and requested shipment window
Frequently asked questions
Should roofing use GI, GL, PPGI, or PPGL?
The shortlist depends on the exposure, expected wetness, cut-edge details, paint system, profile, accessories, appearance target, and maintenance plan. The project specification should compare the complete systems under the same conditions.
Is a RAL number enough to order color coated steel?
A RAL reference helps identify a color family. The RFQ should also state paint chemistry, gloss, texture, substrate, coating thickness, approved sample, color tolerance, and batch planning.
What causes wet storage stain on coated sheet?
Moisture trapped between closely packed sheets or wraps can create staining or corrosion. Bundles need dry transport, prompt inspection, ventilation, suitable slope, and a defined response when wrapping becomes wet.