To Seal or Not to Seal: Metal Roof Repairs

Before applying a roof coating, or treating cut edge corrosion, it is often advised to seal the gap at the end lap of every roof sheet. But should they be left unsealed? According to a technical paper (TP16) originally published in 2004 but updated in 2015, the advice is very much to seal. This paper was produced following testing by MCRMA, which has long recommended butyl strip seals up to 5mm thick for sealing gaps where the sheets overlap.

British Steel also became involved in the debate, having come up with a solution designed to fix problems arising from roof overlap. The British Steel specification was created to prevent rainwater from affecting the overlap through the application of an external seal, which must be flexible, UV stable and with strong adherent properties.

Specific problems surrounding metal roof overlap

When roofing sheets are manufactured, the reverse side is coated with Plastisol, which is applied in a very thin layer. This backing coat is water permeable, and once in contact with water, the zinc layer on the reverse side will start to erode. This is a particular issue at any roof overlap, where the cut edges of the metal sheets are continually exposed to the elements.

Surface tension ensures that water is held on the cut edges of the metal. And once water is drawn into the lap between the sheets, capillary action draws it up further, holding it in place where it can quickly start causing damage. Because the water is held in place within the gap, those exposed parts of the metal sheet never dry out completely, which has the potential to create serious damage over time. Eventually, the zinc layer on the reverse side of the sheet becomes eroded, potentially allowing the ingress of water into the building, compromising the roof’s integrity.

The British Steel specification addresses the problem by the application of an external seal, but this option isn’t without its flaws. Although the seal prevents the ingress of rainwater into the lap, it can also act as a dam. This means water entering the lap due to another issue, such as a failed seal or fixing, is unable to escape. After all, the purpose of an overlap has never been to allow water to drain away from the roof. Capillary action will always ensure water is retained in the lap, and that can lead to expensive problems further down the line, once water damage has occurred.

Is it better not to seal?

When a metal roof has been well constructed, water is unable to enter the lap other than by external means. However, a poorly constructed roof, or failed components, can cause water to dam behind the seal, where it will eventually start to leak into the interior of the building. So perhaps it’s better not to seal. After all, if residual moisture within the lap can’t escape, surely there are bound to be problems at a later stage?

But if the lap isn’t sealed, leaks are almost certain to occur. Without any seal, the capillary action that draws water between the sheets isn’t prevented. Over time, it’s inevitable that the reverse side of the metal sheet will be subject to corrosion, eventually allowing water to leak into the building. The only way to deal with this scenario is to investigate the source of water ingress and stop it from occurring. Once the cause of the leak has been identified and dealt with, it’s essential to dry out the metal sheet as fully as possible before sealing the gap.

Although rust will inevitably develop from the iron content of the steel reacting with oxygen in the presence of water or moisture, this is only temporary when a coating is applied to the lap. As long as there’s no ongoing presence of oxygen, any water within the lap will evaporate as the metal roof is warmed by the sun, resolving the issue permanently.

When it comes to Giromax® products, we not only started this market, but we lead the market. Our coating technology expertise enables us to continually develop products and provide guidance to you and your clients. If you need advice on any of our product range, please speak to the Giromax team or call 01455 558969 today.

The Importance of CPD Training

Regular CPD training ensures up-to-date and effective health and safety policies are led from the top, adhering closely to legal requirements. This usually underpins a company’s health and safety policy statement, setting out the company’s procedures in a clear way. The policy statement should include clear descriptions of who is responsible for specific roles, so that everyone in the organisation has a clear understanding of their own accountability.

Whether you’re a RICS-regulated organisation or you’re a non-affiliated company, every surveyor must comply with its clients’ health and safety requirements. This can involve specific CPD training for contractors and subcontractors and company policies may need to cover:

  • Health and safety training.
  • Identification of potential risks.
  • Clear accountability for health and safety management.
  • Appropriate procedures and policies for managing health and safety issues.
  • Appropriate insurance, including public liability insurance and employer’s liability insurance.

The concept of a ‘safe person’

One of the aims of RICS is to promote the idea of a ‘safe person’. This concept encourages individuals to take responsibility for their own behaviour, while ensuring the safety of their colleagues and any other personnel they encounter during the course of their work.

CPD training enables surveyors to be aware of the latest guidance, so you can implement specific processes on areas including:

  • A safe and secure working environment.
  • Appropriate equipment and safe working systems.
  • Well-trained employees who understand what’s required of them.

The above points are easier to achieve in a low-risk environment, such as an office, but it is much more complex when working on potentially hazardous sites. Therefore, it’s primarily down to managers to ensure health and safety compliance.

The following benefits can be achieved through regular CPD training:

  • Workers have the knowledge and skills to complete the tasks required of them.
  • Ongoing training helps employees recognise and deal with potential hazards.
  • Keeps employees informed about specific risks associated with their work and control measures can be issued.
  • Provides appropriate equipment for employees.
  • Defines safe working practices and ensuring these are adhered to.

Employees have responsibilities too

Using the example of an organisation’s health and safety policy, it’s also down to individual employees to make sure they take responsibility for their own safety. This means ensuring they have the necessary skills and competence to undertake their work safely. They may need to improve their skillset or undertake additional CPD training, if necessary, so they have the ability to recognise their shortcomings and limitations. They can then seek to redress any imbalances.

Adapting to change

It’s down to every organisation to create effective workplace policies, but it’s not always possible to define every type of working environment. The very nature of surveying work means that exposure to a wide variety of working conditions and environments that all offer different challenges is inevitable.

Furthermore, every individual’s perception of risk varies according to the circumstances in which they find themselves. Someone’s age, or previous experience, could influence their decision making. This is something that needs to be factored in when defining potential risks in the workplace and may result in the need for training.

Using the example of health and safety again, regular CPD training helps to ensure a proactive approach to compliance. Every employee should therefore aim to accept the following responsibilities:

  • Cooperate with their employer and other employees to ensure the health and safety of everyone who could be affected by their activities.
  • Accept their own responsibility for keeping themselves safe, by adhering to all requirements, whether defined by law or by management.
  • Share health and safety information with others and strive to promote safe methods of working.
  • Report health and safety risks to management, along with any breaches of the rules.
  • Ensure their own competence is maintained at acceptable levels, when it comes to health and safety concerns.

Specific dangers of working at height

One of the primary risks when working on site comes from working at height, such as when carrying out roof inspections or repairs. For example, scaffolding must be checked by a competent person before it can be safely used, whilst cherry pickers must be certified as safe before being used by a trained operative. For more insights, read our blog Health and Safety – Working at Height on Roofs.

Gable walls, parapets and chimney stacks are always areas of concern, as are bulging, leaning or unrestrained walls. Corroded fire escapes represent an additional hazard, while rotten or corroded beams could cause a roof to collapse, with potentially catastrophic results. By undertaking ongoing CPD training, you and your colleagues will always be aware of the latest guidance on such hazards to ensure health and safety protocols are in place.

When it comes to commercial roofing systems, Giromax® products offer innovative, market-leading solutions for cut edge corrosion and weather damage.

If you need advice on any of our product range, please speak to the Giromax team or call 01455 558969 today.

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Giromax® Data sheets + Specifications, Girocote Data sheets.