Sandwich panel repair or replacement? How to decide

Sandwich panel repair or replacement: what does the decision depend on?

A typical sandwich panel consists of two steel facings and an insulating core bonded into a single element. Damage may affect only the coating, the facing sheet or the whole cross-section of the panel. Which layer has been damaged determines whether a localised repair is enough or whether the element needs replacing.

In its installation guide, Kingspan distinguishes three levels: minor scratches are touched up with touch-up paint, surface damage requires repainting a section, and serious damage to the facing sheets means replacing the facing sheets or entire panels. Ruukki and Balex take a similar view: where the facing sheet is damaged, replacing the panel should be considered. This is a starting point, not a ready answer for every case.

When does a localised repair make sense?

We consider a localised repair when the damage covers a small area, the panel retains its shape, and the panel joint and fixings are intact. Typical examples are scratches and dark marks from tools or equipment, coating chips, localised dents and creases with a damaged surface. Several such areas on one panel do not rule out a repair, but their size and distribution need to be assessed.

Depth matters. According to Kingspan, a scratch that does not reach the steel sheet does not require touch-up painting unless aesthetic considerations are decisive. A scratch reaching the steel must be protected with paint of a suitable colour and composition. Balex and Ruukki recommend repairing minor coating damage without delay, because an exposed zinc layer deteriorates quickly.

Signs that replacing the element should be considered

A surface repair will not restore the panel’s function when the problem goes deeper. In particular, we refer the following for assessment with a view to replacement:

• a punctured or torn facing;
• a deformed or open panel joint that prevents the panel from sitting tight against the adjacent one;
• a damaged or damp core, or one that has delaminated from the sheet;
• a deep dent over a large area or in the fixing zone;
• a deformed flashing, which is usually replaced in its entirety.

A photo does not always show the condition of the core and the panel joint. Where there are doubts about the panel’s load-bearing capacity, insulation performance or fire properties, input from the manufacturer or designer is needed. We do not decide this on the basis of the surface appearance alone.

Replacement also means work on adjacent elements

Replacing a panel in a finished envelope usually means removing flashings and fasteners, sometimes adjacent elements as well, and ordering a panel with the same profile, thickness, core and colour. Access, protection of the interior and building operations during the replacement also need to be planned.

A new panel does not always look the same as the adjacent ones. Ruukki recommends checking for shade differences when combining panels from different production batches, and the coating on the building also changes with age. That is why, with both options, repair and replacement, it is worth discussing the expected result before deciding.

Construction damage: decide before handover

Some scratches and dents occur during construction: during unloading, installation or the work of other trades. Ruukki states in its installation instructions that damaged panels should not be installed and that the manufacturer does not cover the cost of replacing installed damaged panels. Balex and Ruukki recommend repairing minor coating damage that occurs during installation without delay.

For a main contractor, the best time to decide is before handover. Kingspan recommends inspecting the envelope immediately after construction is completed. A schedule of damage with photos and locations makes it possible to separate areas for localised repair from elements to be replaced before the building passes to the occupier.

What do we assess from photos, and when is a site survey needed?

From photos, we assess the type and size of the damage, its position relative to the panel joint, fixings and flashings, the number of areas and the condition of the surrounding coating. A close-up with a scale shows the depth of a scratch or dent, and a wider shot makes it possible to check whether the panel is deformed over a greater length.

We suggest a site survey when the photos do not show the joint between panels, when there is a lot of damage, when we suspect the core is damp, or when the damage is on the roof or high up on a wall. We repair wall and roof panels; we take on roof work after assessing access and the conditions for carrying it out safely. During the repair, we also check the joint sealing and make it good in line with the panel manufacturer’s system.

Manufacturer’s instructions and warranty: check before work starts

Before we start, we check the documentation for the specific panel and its warranty terms. The Kingspan warranty certificate excludes mechanical damage from the warranty and requires defects to be reported in writing within 7 days of discovery at the latest. The same certificate makes the validity of the warranty conditional on annual inspections, of which the manufacturer must be notified in advance. Other manufacturers have their own terms, so we do not automatically apply them to every panel.

Kingspan also notes that repainting a section of a panel requires the original coating to be abraded to a matt surface and entails loss of the warranty on that coating, and that a visible difference in shade may remain after a touch-up. That is why we agree the effect of the repair on the warranty with the building owner before work starts. We do not promise that the manufacturer’s warranty will be preserved or that the repair will be invisible. Citing manufacturers’ documents does not mean that Panel Cure+ is authorised by these companies.

How do you prepare an enquiry for assessment?

A good enquiry shortens the path to deciding whether to repair or replace. Prepare:

• the site location and the reference of the wall, gridline or roof slope;
• a close-up photo with a scale, for example a ruler, and a wider shot of the whole panel;
• the number of damaged areas and their approximate dimensions;
• the manufacturer, panel type, thickness, core and RAL colour, if you know them;
• information on access, height and building operations at the repair location.

Do not go onto a roof or platform just to take a photo. We will establish any missing data when we talk. We give the method, scope, price and timing after assessing your enquiry.

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: installation guide, chapter 5, inspections and maintenance, edition 08.12.2025 (v4)
2. Ruukki: sandwich panel installation instructions, CPL 025 PL, 12.2025, pp. 4 and 12 and part IV, maintenance (p. 22)
3. Balex Metal: sandwich panel maintenance and washing instructions, 31.01.2024
4. Kingspan: sandwich panel warranty certificate with annex on panel assessment, edition 11.12.2025 (v5)