Steel Roofing Sheet Coatings Explained
Choosing the right coating for your steel roofing sheets or wall cladding is one of the most important decisions you’ll make for your project. The coating determines the colour, durability, appearance and lifespan of your sheets. All of our roofing and cladding profiles are available in the coatings listed below.
Galvanised
The most economical option. Galvanised steel is coated on both sides with a layer of zinc, which protects the base steel from corrosion. The finish is initially shiny and metallic, dulling over time to a matte grey. Galvanised sheets are unpainted and available in one colour only — natural zinc silver.
Galvanised is ideal for agricultural buildings, barns, sheds, storage buildings and utility structures where appearance is less important than cost and corrosion resistance. It is also commonly used as a liner sheet in twin-skin insulated systems.
Typical lifespan: 20–30 years depending on environment and exposure.
Polyester (25 micron)
A cost-effective coated option. Polyester paint is applied at 25 microns over a galvanised base, giving a smooth, semi-gloss finish. It provides good colour retention and UV resistance, making it suitable for both roofing and wall cladding applications.
Polyester is available in a range of standard stock colours and is the most popular choice for domestic projects, garden buildings, garages and light commercial buildings. The smooth finish gives a clean, modern appearance.
Typical colour life: 10–15 years.
Finish: Smooth, semi-gloss.
Thickness: 25 microns over galvanised steel.
Plastisol (200 micron)
Our most durable coating. Plastisol is a PVC-based coating applied at 200 microns — eight times thicker than Polyester. It has a distinctive leather-grain textured finish that is highly resistant to scratches, weathering and fading. Plastisol is the premium choice for projects where longevity and durability are the priority.
Plastisol is the most popular coating for agricultural, industrial and commercial roofing in the UK. Its thickness makes it far more resistant to damage during handling and installation compared to Polyester, and the textured finish hides minor surface imperfections.
Typical colour life: 15–25 years.
Finish: Leather-grain texture, semi-gloss.
Thickness: 200 microns over galvanised steel.
Polyester Powder Coat (PPC)
Any RAL colour, made to order. Our powder coating service allows you to order any of our roofing or cladding profiles in any of 214 RAL colours. The sheets are powder coated on either aluzinc steel (0.7mm) or aluminium (0.9mm), giving you a durable, high-quality finish in your exact colour.
Powder coating is the right choice when your project requires a specific RAL colour — whether to match an architect’s specification, corporate branding, planning requirements, or simply because you want a colour that isn’t available in our standard Plastisol or Polyester range.
Typical lead time: 5–7 working days.
Finish: Smooth, available in multiple textures.
Thickness: 70 microns (polyester-based powder coat).
Browse our full range of 214 RAL colours here.
Coating Comparison
| Galvanised | Polyester | Plastisol | Powder Coat (PPC) | |
|---|---|---|---|---|
| Coating thickness | Zinc only | 25 microns | 200 microns | 70 microns |
| Finish | Metallic (dulls over time) | Smooth, semi-gloss | Leather-grain texture | Smooth (multiple textures available) |
| Colour life | N/A (unpainted) | 10–15 years | 15–25 years | 15–20 years |
| Scratch resistance | Low | Moderate | High | Moderate |
| Colour options | 1 (zinc silver) | ~15 stock colours | ~15 stock colours | 214 RAL colours |
| Best for | Budget builds, agricultural, utility | Domestic, light commercial | Agricultural, industrial, commercial | Architect specs, colour matching |
| Lead time | 5–7 working days | 5–7 working days | 5–7 working days | 5–7 working days |
| Price | Lowest | Mid-range | Premium | Premium |
Which Coating Should I Choose?
On a budget? Choose Galvanised for the lowest cost per metre. It provides excellent corrosion resistance without the cost of a painted finish.
Want colour at a good price? Choose Polyester. The smooth finish looks great on domestic buildings, garages, garden rooms and extensions. Available in stock colours for fast delivery.
Need maximum durability? Choose Plastisol. The 200 micron thickness makes it the toughest coating available — ideal for exposed sites, agricultural buildings and anywhere the sheets might take a knock during installation or use.
Need a specific RAL colour? Choose Powder Coat. Our powder coating service can produce any of 214 RAL colours on aluzinc steel or aluminium, with a typical lead time of 5–7 working days.
All coatings are available across our full range of roofing and cladding profiles. If you’re not sure which coating is right for your project, call us on 0161 343 2060 and we’ll help you choose.