How long does a sandwich panel last? The short answer

There is no single figure that applies to every sandwich panel. Manufacturers do not give a universal service life: they link durability to the specific coating system, the environment in which the building stands, the colour and how it is maintained. Two industrial buildings made of similar panels can age at different rates if one stands in a clean environment and the other next to a chemical plant or by the sea.

It is also worth distinguishing the warranty from the service life. A warranty is a manufacturer’s commitment under specified conditions and does not mark the end of the panel’s working life. According to SSAB’s instructions, products with a GreenCoat coating retain their properties for a very long period when properly maintained. Below we summarise what manufacturers’ documents say about durability.

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The panel warranty and the coating warranty are different documents

An example from Poland: the Kingspan warranty certificate (edition 11.12.2025) covers 5 years for panels with a foam core and 3 years for panels with a wool core, counted from the date of manufacture. Among other things, the warranty does not cover mechanical damage, the effects of improper cleaning or changes in shade resulting from natural ageing of the coating. It becomes invalid if the user does not carry out annual inspections reported to the manufacturer.

Coated steel manufacturers sometimes give a separate, longer warranty for the coating alone. In its Confidex guarantee datasheet, Tata Steel gives up to 40 years for Colorcoat HPS200 Ultra and Colorcoat Prisma coatings on roofs and walls, including in sandwich panels, and up to 20 years’ colour guarantee for standard Colorcoat Prisma colours. The period is shorter for buildings within 1 km of the coast and in the Southern Europe zone, depends on the colour group, and the guarantee must be registered within 3 months of completion of construction. These figures relate to the products specified and are not a forecast for every panel.

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Coating system: thickness and resistance classes

The durability of the facing depends most on the coating applied to it. In its coating data sheets, Kingspan describes SP25 polyester, 25 µm thick, as a coating for normal external environments: corrosivity category C3, corrosion resistance RC3 and UV resistance RUV2. According to the same brochure, the PUR-PA50 polyurethane coating, 50 µm thick, has category C4, RC4 and RUV4.

In its panel catalogue, Ruukki shows a similar relationship: 25 µm polyester has classes RC3 and Ruv 2, and GreenCoat Pural BT Satin, 50 µm thick, RC5+ and Ruv 4-5. The manufacturer notes that additional consultation is needed for environments more aggressive than C3/RC3. The practical conclusion: before assessing durability or a repair, it is worth knowing the name of the coating from the delivery documents.

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Environment and colour accelerate ageing

Balex points out that the facing material is selected at the design stage according to the corrosivity of the environment as defined in PN-EN ISO 12944-2. Constant moisture, standing water and chemical vapours promote corrosion, and accumulated dirt holds moisture on the surface. The Kingspan warranty certificate does not cover damage in an environment with a corrosivity category other than that agreed with the manufacturer, including after a change in how the building is used.

Colour matters for two reasons. SSAB identifies UV radiation and air pollution as the factors with the greatest impact on organic coatings and recommends renewing dark colours earlier than light ones. In its panel calculations, Ruukki assumes summer temperatures of the external facing of +55°C for very light colours, +65°C for light colours and +80°C for dark colours, which include RAL 7016 among others. A dark panel therefore works under a greater thermal load.

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Damage that exposes the steel is where corrosion starts

The steel facing is protected by two layers. Kingspan describes this as a DUPLEX system: a 275 g/m² zinc coating and a paint coating. When a scratch or impact breaks through the paint, contaminants come into direct contact with the zinc. According to Balex’s instructions, readily soluble salts then form, the zinc layer deteriorates quickly and the damaged area stays damp for longer, which accelerates corrosion.

That is why manufacturers recommend repairing minor coating damage without delay, including damage that occurs during installation. SSAB adds that a surface repainted at the right time can achieve a service life of more than 50 years. This is a maintenance condition described for GreenCoat steel, not a promise for every panel. Panel Cure+ repairs localised damage; painting entire facades is not part of our offer.

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Inspections and cleaning: how often?

Kingspan and Balex recommend inspecting panels at least once a year, and Balex adds that the more aggressive the environment, the more frequent and thorough the inspection should be. Kingspan recommends the first inspection immediately after construction is completed. For GreenCoat steel, SSAB specifies a minimum of one inspection every two years. During an inspection, it is worth looking at panel edges, connections with flashings, fasteners and areas not washed by rain.

We describe a plan for inspections, cleaning and a simple log of reports in the article Sandwich panel maintenance. The cleaning agent and washing method are selected for the specific coating in line with the manufacturer’s instructions.

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When should damage be reported for assessment?

Report any area where a scratch or chip exposes metal, where blistering, flaking, rust-coloured or white deposits appear, and any dent after an impact. The sooner the damage is assessed, the less likely it is that the change will spread. Send a close-up photo with a scale, a wider shot and the location; if you know the panel manufacturer and the coating name, add them. We will assess whether a localised repair is enough or whether a different scope of work is needed.

Sources and scope of information

Checked on 24 October 2026. Based on the sources listed below. This educational content was prepared by Panel Montage. The procedure depends on the specific panel, coating, damage and manufacturer’s recommendations. This article is not an individual repair assessment or an instruction for working at height.

  1. Kingspan: sandwich panel warranty certificate with annex on panel assessment, edition 11.12.2025 (v5)
  2. Kingspan: sandwich panel coating data sheets, edition 01.08.2025 (v3), pp. 2 and 8
  3. Ruukki: sandwich panel catalogue, valid from 25.09.2026, p. 12 (colour groups) and p. 14 (coatings)
  4. Ruukki / SSAB: maintenance of GreenCoat coated steel, April 2024, pp. 2-4
  5. Tata Steel: Confidex Guarantee, datasheet in English, 06.2020
  6. Kingspan: installation guide, chapter 5, inspections and maintenance, edition 08.12.2025 (v4)
  7. Balex Metal: sandwich panel maintenance and washing instructions, 31.01.2024

Let’s start with photos

Show us the damage.
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Prepare a view of the whole panel, a close-up of the damage and the site location. If you know the manufacturer, coating type or RAL reference, add this information.

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