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Corroded roof sheet panel

What is Cut Edge Corrosion?

In recent years, industrial cladding sheets are used on a variety of commercial grade buildings such as Hospitals, Medical Centres, Warehouses, Retail Units and any other type of commercial building that is exposed to a lot of harsh weather.

A lot of facilities managers and business owners find themselves asking what is cut edge corrosion?

How has cut edge corrosion developed over time?

In the early days of commercial cladding installations, they were predominantly used for barns and sheds. Over the years, this material has had to evolve with the changing architectural trends and become stronger as a result. We are now seeing cladding panels used as more of an aesthetical feature to improve the overall appearance of a building.

When the cladding panels are being manufactured, the sheeting is coated in plastic. It may seem a little strange, but this plastic protects any underlying metal from corrosion and helps add to its appearance.

The corrosion becomes visible when the cladding sheets are exposed to the elements without any protection. Over 60% of property owners are unaware that their cladding may, in fact, have cut edge corrosion.

Metal guttering can also be affected by cut edge corrosion; if guttering is clogged up and remains damp, it can experience erosion. If your guttering starts to erode, it can cause structural damage which can be a significant safety hazard.

What actually is cut edge corrosion?

When you have your cladding panels made for your property they are usually cut to size. Once they have been cut the plastic coating that was previously applied is not reapplied to the edges. Over time, the steel edge of the cladding panels become exposed to oxygen. A mixture of oxygen, pollutants and constant water exposure will make the edges of the cladding prone to corrosion. Unfortunately, this also means that the factory plastic coating will also start to peel away from the edges.

So what do you do when you discover a panel layered with corrosion?

How to Fix Corroded Panels

If you believe your property to have cut edge corrosion, we highly recommend carrying out an assessment of the cladding panels. A lot of clients we have here at CJ Paint Spraying believe only a small area of the property has been affected when in reality it can be a fair amount of cladding affected. Once you have completed your own assessment, we recommend calling in a specialist to also carry out an assessment of the cladding sheets in question. A qualified contractor will be able to identify any affected areas but can also inform of any of the causes of corrosion that may be easy to prevent.

Identify Severe Areas
Being realistic with your sheets is essential. Your chosen contractor will be able to help you out here. You need to be able to determine the parts of the sheeting that is not salvageable. It’s better to be realistic than optimistic at this point. If you do have any sheets that need replacing contractors will be completely honest with you. Here at CJ Paint Spraying we only repair what is essential, unlike cowboy builders we will not spray or coat areas that are perfectly fine.

Remove Moss and Grime
Once the severely damaged sheets have been identified and removed, you will need to remove any existing moss, dirt, grime and mould from the area.

Any cladding repair contractor worth their salt will be able to do this quickly and with little fuss. They will also look to remove any flaking paint that remains mechanically.

Start Fixing
Once the dirt has been withdrawn a team will begin doing what they can to repair the cladding and corroded metal sheets. Any uneven panels will be sanded back (some prefer to use the term feathered) to reduce the chances of any additional damages.

The cladding sheets will then need to be thoroughly cleaned again. This helps to remove any final pieces of grime that could still be present in the roofing structure. This section is extremely important if you go to recoat the cladding without the right cleaning process the paint is less likely to stick. It can also cause the paint to bubble and pucker which only means one thing. You will more than likely need your cladding panels resprayed quicker than you initially thought.

As the repairs are being completed, many significant gaps may start to appear in the sheets. The best way to resolve this issue is to use a sealant gun to close the spaces as quickly as possible. We ensure all areas are correctly filled we have been to a few sites whereby another contractor has incorrectly filled the corroded areas leaving the clients with leaking roofs.

Once the cladding has been reinstalled and the damaged sheets removed, the cladded area will need to be re-sprayed. This is to help match your buildings existing colour schemes and provide a protective coating. This will prevent future damages to your roofing panels and save you a considerable amount of money in future repairs. It also increases the lifespan of your cladding significantly, reducing the need for regular maintenance.

Another thing to think about is if you are looking to change the colour of your cladding now would be a good time. CJ Paint Spraying, for example, have an in-house colour matching service which allows us to formulate the paint perfectly to your specific colour.


Cladding panels are vulnerable to corrosion when they are fresh from the manufacturer’s warehouse. This is due to the protective coating being non-existent at this stage. Which is why it is so important for you to have a professional contractor spray the sheets as soon as possible to prevent future corrosion.

If you feel your cladding sheets are corroding we highly recommend having a spraying contractor attend site as early as possible so they can assess any damage. Try not to leave any corrosion over an extended period of time as you will only find cladding sheets may need complete removal costing you more in the long run.

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“We have used CJ Paint Spraying a couple of times for on site spraying services along with repairs to our external cladding. All of the work they have completed for us has been spot on! It always looks brand new, and the teams are friendly and professional, we couldn't recommend enough.”

David Netherway 14th March 2018