What is the Best Treatment for Cut Edge Corrosion in Profiled Steel Roof Sheeting?

What is Cut Edge Corrosion?

Roof sheet manufacturers’ performance statements refer to the lifetime of the pre-finished steel sheet in terms of the period when the building owner must consider whether to re-paint the sheet, either to upgrade the aesthetics or to preserve protection of the steel substrate. Within that lifetime, edge peel may arise from normal weathering. It is most often seen at sheet overlaps and at eaves and gutter overhangs, and if neglected, this edge corrosion can eventually compromise the structural integrity of the sheet.

The development of cut edge corrosion is difficult to predict. It is progressive by nature and accelerates in proportion to the accumulation of conductive elements especially capillary held water, eventually overcoming the protective sacrificial barrier which is usually zinc or a zinc alloy. Ideally, long sheets from ridge to eaves should be specified, reducing the need for overlaps. In practice, this is not always possible where long runs or translucent sheets are required.

Cut Edge Corrosion

How can we treat Cut Edge Corrosion?

If the problem of cut edge corrosion has subsequently arisen, its treatment must necessarily follow a specification that excludes water from the lap, without the ability to lift and reset the roof sheets. In addition, the joint must remain flexible enough to accommodate stresses from building movement, sheet expansion and foot traffic and withstand extremes of weathering, temperature, and UV.

This is a difficult specification to achieve and one that was best serviced for many years by the use of the traditional silicone system. Successful treatment however, depended on two key factors which inevitably could be viewed as system limitations.

What are the limitations of traditional silicone based treatments?

1. Firstly, corrosion control depended entirely on the adhesion properties of silicone in being able to smother and starve the substrate of the two main agents of rust – air and moisture.

Using a silicone-based system, adhesion can only be achieved on a completely dry surface.

2. Secondly, to fully accommodate sheet movement and keep the lap sealed, the system must remain flexible.

A silicone-based system remains relatively soft, especially during its curing cycle which makes it potentially vulnerable to impact and abrasion damage, especially from the curiosity of birds.

So what options are available that avoid the limitations of silicone based systems?

With these restrictions in mind Giromax have introduced a more technologically advanced solution.

Giromax® uses the latest hybrid technology that takes full advantage of properties introduced and developed to overcome the application and wear limitations of silicone alone.

Fully moisture tolerant, the Giromax® system can adhere to all surfaces in the treatment of corrosion, by penetrating and binding at the molecular level to barrier air and moisture from the substrate using laminar flake technology.

By removing application restrictions and performance limitations, the Giromax® system achieves complete adhesive encapsulation of the overlap, hardening to a tough elastic coating with high impact and abrasion resistance.

What impact will this decision have on your commercial roofing project?

Using the latest technology and avoiding the limitations of traditional silicone systems will lead to better results in less time, saving on labour costs and allowing you to complete more work faster.

If you are still using traditional silicone based systems, here are the reasons why you need to shift to Giromax technology:

– One Coat System

– Use straight from the tin

– Comprehensive Colour Range – at no extra cost

– Same Day Wash and Apply

– Reduced Labour & Access costs

– Cures harder – resilient to ‘Bird Attack’

– Less time spent on site and working at height

– 20 Year Guarantee

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9 Reasons Why Recoating your Commercial Roof Will Save You Money

1- Your roof may fail under the added weight…

The first consideration must be whether or not the building structure will bear the weight of another layer of recommended gauge steel sheets and supporting framework. Calculations must factor in snow loading.

2- More holes = more problems down the line

‘Through fix’ installations that utilise the existing purlins must necessarily involve drilling further holes in the existing sheet, risking moisture penetration and air leakage leading to condensation.

3- You will create the issue of CONDENSATION…

Where the old roof is retained as a liner, a new vapour protection layer must be added if it cannot be sealed. The VCL should be located above what will become the internal sheet but is difficult to seal when punctured with fixings for the support brackets for the new skin, risking ‘cold bridging’.

4- Matching performance properties for all other materials

A vast array of support and ancillary fixings, sealants and thermal performance materials must match the design life guarantee of the chosen over-sheet system.

5- Over-sheeting causes heavy disruption to your site

A strictly controlled programme involving large and heavy deliveries, storage, movement of men and materials and handling must be carefully planned and safely managed.

6- Recoating is inevitable!

Like the original sheet, the over-sheet will itself need recoating as it reaches its normal expected repaint schedule. The same factors affecting performance will prevail on the factory coating of an over-sheet option. Cut edge corrosion will almost inevitably occur during its lifetime.

7- Recoating is the sustainable choice…

Steel sheet production requires large resources of finite raw materials and energy. Having a steel roof already in place requires only recoating to protect it indefinitely.

8- Life-cycle costs far greater with over-sheeting

Over-sheeting means double roof sheet disposal at building end of life.

9 – Giromax® Roofcoat is revolutionising the coating industry…

Giromax® Roofcoat is the NEW cut edge corrosion treatment from Giromax Technology, achieving better results for longer. It can be sprayed directly from the tin. No mixing required. And like previous versions is fully moisture tolerant which means it can be applied to wet surfaces, hardening to a tough elastic coating with high impact and dirt resistance. This single coat system also comes with a 20 year guarantee.

Planned repainting will extend profiled metal sheet life indefinitely, maintaining the strength and value of the building without disturbance. Over-sheeting by comparison is heavy, increases the risk of leaks & condensation and leaves the same coating failure dilemma further down the line. In essence, the roof protection is now provided by a sheet with characteristics and weaknesses possibly worse than that being over clad, with an unnecessary layer of steel effectively doubling sustainable planned maintenance and life cycle costs.