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Cut Edge Corrosion Treatment

BBA Approved cut edge corrosion treatment from Liquasil

BBA Approved cut edge corrosion treatment from Liquasil is designed by building surveyors and is widely specified throughout the UK by leading building surveying practices.

Utilising our SWT Corrosion Primer, a marine grade epoxy that stops and prevents rust, Flexlap provides many years protection against cut edge corrosion and is cheaper than all other commonly specified cut edge corrosion treatments.

How Cut Edge Corrosion Treatments Fail

If you' have historically specified the type of cut edge corrosion treatment that seals the space between overlapping metal roof sheets, be sure to watch this video.

You could be creating a latent defect that could result in the roof sheets rotting away beneath the treatment.

How To Treat Cut Edge Corrosion For Less

Step 1: Prepare surfaces by removing all loose and flaking materials. and feathering-in any lifting edges

Step 2 : Apply SWT Primer to prepared areas at wet film weight of 100 microns

Step 3: Apply Flexlap to primed areas at a wet film weight of 300 microns

If you want to know how to treat cut edge corrosion effectively and economically, Liquasil’s BBA Approved Flexlap system is all you’re going to need.

About Flexlap Cut Edge Corrosion Treatment

Designed by building surveyors, independently tested by The British Board of Agrément (BBA) and recommended by Kingspan, Liquasil's cut edge corrosion treatment is vastly different from any other system on the market.

Instead of masking the problem with paint primers and expensive sealants, Liquasil’s cut edge corrosion treatment includes a rust treatment that is already proven in the harshest marine environments.

More than 1million sq metres of the primer has been installed during the past 15 years in the petrochemical and offshore sectors, with zero failures.

We call it SWT Primer.

SWT stands for Surface & Wet Tolerant, meaning that it can be applied to red rusted surfaces, even if they are soaking wet or under water.

Once cured after around 24 hours, the  SWT primer is overlaid with the unique, hardened silicone top-coat, Flexlap.

Flexlap is a self-levelling silicone coating designed to extend the life of the system even further by providing a 100% UV stable finish that’s available in any RAL colour, subject to certain minimum ordering quantities.

All silicone coatings attract environmental dirt pick-up, but Flexlap can cleaned with plain water and a little household detergent and sponge if necessary, with no need to use a fungicidal wash.

Should You Seal The Gap Between Overlapping Roof Sheets?

Some cut edge corrosion treatments involve sealing the gaps between over-lapping roof sheets.

If you’re selling tubes of silicone at around £12-14 each, this is a great idea, but most of the time, it’s expensive, unnecessary and probably ill advised.

Click on the video at the top of this page and you’ll see that sealing overlapping roof sheets can cause a serious latent defect in your metal roof.

Sealing overlapping roof sheets is not required in most cases and therefore, our cut edge corrosion treatment is designed to treat only the sheets that are suffering from the problem – the top sheets.

Our discussions with metallurgists, roofers, building surveyors and sheet manufacturers back up our assumptions and our inspections of many roofs also provides further supporting evidence.

This results in a far easier application method, significant material and labour savings and an altogether more robust solution to cut edge corrosion problems.

Installers love it for the sheer simplicity and clients love it because it saves them money.

BBA certification adds another layer of assurance to this proven product.

Liquasil Ltd is owned by building surveyors and our liquid roofing solutions are designed to actually solve the problems associated with commercial roofs.

The Liquasil Cut Edge Corrosion System is so good  that we can provide a number of warranty options when installed by a Liquasil Approved Installer, in addition to our standard 15 year product warranty.

Sometimes, it might be necessary to seal the gaps on the overlapping roof sheets, for example when the corrosion is particularly severe, or the pitch of the roof is causing water ingress during wet, windy weather.

In cases like this, we do have a product called “Lapsil” that will seal the overlapping sheets. This MUST be specified in advance.

Sometimes, the cut edge corrosion will be severe enough to have rotted the ends of the roof sheets, particularly in cases where another cut edge corrosion treatment that seals overlapping joints has been employed previously.

Once this has happened, it is difficult to repair and in these cases, it is often preferable to consider replacement sheets, or to over-clad the roof in question. We are always available to advise professional specifiers if they are in any doubt as to the best solution.

However, for those cases where replacement or over-cladding is not desirable, we can supply a 100mm wide fleece to bed into the Flexlap to create a permanent, flexible seal that will withstand foot traffic without breaking, as long as the flex in the roof is not too great.

We can also provide an alternative polyurethane based top coat for situations where the roof sheets are really too far gone for a coating solution.

If you need any help in understanding the real issues surrounding cut edge corrosion, we offer a free, comprehensive, roofing CPD session on the subject.

For a more reasoned approach, contact Liquasil Ltd on 0121 709 5352 and speak to one of our surveyors without obligation.

BBA Certificate number: 18/5536 (sheet2)


Building surveyors often specify cut edge corrosion treatments that include a sealant to seal the gaps between overlapping roof sheets. The silicone used is no more effective than any external grade silicone you can buy at a builders merchant, yet the price is often around £12 per tube, which provides around 6 linear metres of coverage.

When the gaps are sealed and the roof is trafficked (even during application), the roof sheets will flex and often, the silicone seal breaks. This creates a capillary action that draws water into the gap, where it becomes trapped, causing underside corrosion of the roof sheets. Over time, the roof sheet rots away and damages the bottom sheet as well as the top sheet.

Therefore, it is our belief that the cut edge corrosion treatments that have been specified historically, can create a significant latent defect in a metal roof that cannot be easily repaired. If you are inspecting a roof for dilapidations purposes, with a previously installed cut edge corrosion treatment, we will be happy to show you how you could increase your dilapidations claim.

Call us on 0121 709 5352.