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A Guide to Flat Roof Solutions and Systems

A cartoon of a building complex with multiple flat roof solutions and systems
Flat roof solutions and systems have become increasingly more important in recent years due to their sleek and modern design and to maximise space utilisation.

The numerous advantages of a flat roof, such as offering additional outdoor space, energy efficiency, and ease of installation have aided this increase in demand.

Whether you're considering a flat roof for your new construction project or thinking about replacing or refurbishing an existing roof, this guide will walk you through everything you need to know to make an informed decision.

Why Choose a Flat Roof?

A flat roof has several benefits compared to a standard roof that make them an attractive option for both residential and commercial buildings:


Installation costs for flat roofs are often lower than traditional sloped roofs because they require fewer materials and less labour.

Energy Efficiency

Flat roofs can be equipped with reflective materials that help regulate indoor temperatures, reducing the need for excessive heating or cooling.

Ease of Maintenance

A flat roof is easier to access and maintain compared to a typical sloped roof making regular inspections and repairs much more straightforward.

Space Utilisation

One of the most significant advantages of a flat roof is the extra space it provides. You can use this space for a rooftop garden, outdoor lounge, or even solar panels to generate green energy.

Types of Flat Roof

Before making a decision on your flat roof, it's crucial to understand the different types available:

A single ply membrane used on a flat roof

Single Ply Membrane

This type of flat roof uses a single layer of synthetic material, such as EPDM or TPO. It's lightweight, cost-effective, and resistant to UV rays.

Cold Applied Liquid Waterproofing

This flat roof solution is a single component liquid made from pure polyurethane making it airtight and waterproof. Explore this solution more on the Arboflex PU page.

A single ply membrane used on a flat roof
ARBOFLEX®PU Liquid Waterproofing - W
A single ply membrane used on a flat roof

Green Roof

A green flat roof includes vegetation, soil, and a waterproofing membrane. It offers insulation benefits, stormwater management, and aesthetic appeal.

Flat Roof Installation and Maintenance

Proper installation and regular maintenance are essential to ensure the longevity of your flat roof. It's advisable to consult with a professional roofing contractor for installation.

Key flat roof maintenance tasks include:

  • Regular inspections for cracks, leaks, and damage

  • Cleaning debris such as leaves and dirt will prevent blocked drainage. Local build-ups of soil should be swept off to prevent the growth of rooted vegetation

  • Keeping rooftop gardens well-maintained

A contractor adding a safety system walkway to a flat roof

Flat Roof Safety

Safety should always be a top priority when dealing with flat roofs. Ensure that access points are secure, and consider installing guardrails or safety nets if necessary.

Safety system walkways are a non-slip, EPDM based safety covering specifically designed for flat roofs.

These walkways not only protect your flat roof but contain traffic routes for inspections and maintenance services.

More Benefits of A Flat Roof

A flat roof can be more than just a part of your building's fabric and can be a valuable resource for the building and its location even offering additional space to a build environment.

Green Roofs

Flat roofs can also play an important role in enabling green credentials that may be included in the building design and specification with the addition of green roofs.

Carlisle® flat roof solutions, such as RESITRIX®, HERTALAN® and ARBOFLEX®PU, all have the potential to enhance biodiversity and embed green space into development projects, whilst also offering excellent root resistance to prevent damage to your flat roof.

Enhancing Ecological and Sustainable Benefits With Flat Roofs

Operators of large buildings, such as logistics hubs and factories, are increasingly aware of the need to invest in environmental best practice as part of their ESG commitment.

They are also more conscious than ever of the operational cost and benefits of using renewable energy, rather than relying on the grid.

As a result, companies such as Amazon are installing solar panels on both their new build flat roofs and their refurbishment projects to meet commitments.

Therefore, the consideration of solar panels on large flat roof specifications, at either the build stage or for future use, is more important now than ever.

Carlisle® Flat Roof Solutions

At Carlisle®, our EPDM and TPO flat roof systems are designed to support the installation of energy saving and sustainable materials such as solar panels.

Our latest TPO product, SURE-WELD® TPO is deliberately light in colour to provide reflective properties that help to maximise the amount of energy conversion from solar panels.

A contractor adding a safety system walkway to a flat roof

How Flat Roofs Are Helping With The Urban Heat Island Effect

One of the most instantly recognisable features of CARLISLE’s flat roof system such as ARBOFLEX® PU liquid waterproofing and SURE-WELD® TPO roofing membrane is its colour.

TPO is available in a variety of colours including pale grey or white. The significance of this is much more than aesthetic, as the light roof covering reflects heat, preventing solar gain that not only heats up the fabric of a building, but also increases the heat of cities and urban environments.

Heat absorption and retention by buildings is a phenomenon known as the urban heat island effect, but it is not confined to urban areas.

It can also affect industrial estates, logistics hubs, large hospital complexes, essentially any environment where large expanses of roof, especially flat roofs, have the potential to absorb or reflect heat.

It is a problem that is growing exponentially, as the level of urban density and the scale of industrial and logistics buildings increases.

Worse still, the factors affecting the heat absorbed and retained by a building exacerbate each other: the warmer the climate, the more heat a building will absorb; the warmer buildings become, the more they rely on cooling systems, which generate heat and require energy that may contribute to global warming.

How Can a Carlisle® Flat Roof System Help?

While a heat-reflecting flat roof covering such as ARBOFLEX® PU and SURE-WELD® TPO is not a complete solution to the urban heat island effect on its own, it is a key element of the role that the specification of the building fabric can play in reducing this issue.

When specified in combination with energy efficient building services and an insulated building envelope that reduces heating and cooling requirements, a heat-reflecting flat roof can form part of a robust environmental strategy.

The Importance of Flat Roof Waterproofing Membranes 

The flip side to the higher temperatures the world is experiencing due to a changing climate, is the level of rainfall we’re getting, which is only predicted to increase in the coming years.

A flat roof system is essential to ensure the building structure is fully waterproof and to reduce the risk of leaks at seams or fixings as well as providing consistently high levels of waterproofing performance throughout its lifespan.

Fitting Large Flexible Membranes

When installing larger flat roofs, having a large and flexible membrane enables the construction team to fit the membrane quickly and efficiently ensuring it is watertight as quickly as possible.

Carlisle’s SURE-WELD® TPO system is the ideal solution for large flat roofs with its enhanced durability, flexibility and simple installation process. The membrane can also be removed cleanly and easily from the roof at the end of its service life.

Long Lasting Flat Roofs

Our EPDM, TPO and liquid waterproofing flat roof systems contain no environmentally hazardous toxins or plasticisers

This means they won’t crack or blister over time, retaining their elasticity and consistent performance throughout their entire service life. 

Even our single layer membranes don’t need softeners, release zero toxins into the atmosphere, and have a high level of temperature stability ensuring a maximum life expectancy.

Octaguard XT

Octaguard XT weather protection technology, an active ingredient combining U/V and temperature stabilisers, provides improved durability and flexibility to the Carlisle’s SURE-WELD TPO® flat roof system, 

OctaGuard XT combines eight performance-enhancing ingredients, including three heat-stabilising antioxidants and three UV light stabilisers as well as organic and inorganic UV absorbers.

In addition to providing industry-leading levels of weathering protection, OctaGuard XT also enables the SURE-WELD TPO system to be resistant to dirt, mould, bacteria and other contaminants.

This ensures the flat roof system stays whiter for longer, maintaining its efficiency and lifespan of the roof covering, improving sustainability and reducing operational and cost factors.

Safe & Flame Free Installation

Our RESITRIX® waterproofing membranes can also be easily and safely welded together with a hot-air gun without any open flames, avoiding any risk of fire.

The underside of the waterproofing membrane can be welded with hot air, allowing you to freely choose the width of the connecting and finishing strips reducing material losses.

A visual inspection is sufficient to check the hot-air welding and a clearly visible bead of bitumen will indicate a proper weld.

EPDM Flat Roofing Systems

HERTALAN® Easy Cover can provide every flat roof with a durable EPDM waterproofing. Our special hot bonding technique (vulcanisation) can weld EPDM sheets together at our factory.

This way, HERTALAN® can produce an EPDM flat roofing system that can virtually seal an entire roof at once. We can produce membranes up to 30m in length and in various widths up to 20m, reducing the number of laps required on site and the number of seams and related risks are therefore kept to an absolute minimum.

HERTALAN® Easy Cover EPDM membranes are suitable for exposure to UV and ozone radiation without ageing and can therefore be used as adhered and mechanically fixed systems without the requirement for additional surface protection.

Flat Roof Solutions for The Future

Both the construction industry and the wider world are looking for solutions that reduce waste and avoid materials that are hard to recycle. In Berlin, for example, the authorities have banned PVC products, including PVC roof coverings, indicating a need to consider alternatives.

EPDM membranes such as HERTALAN and SURE-WELD®TPO can be recycled at the end of their service life making them the perfect solution to replace PVC roof coverings.

SURE-WELD® TPO is made using recycled materials and can be removed cleanly from the roof for re-use or recycling at the end of its service life, lowering maintenance and reducing whole life costs.

TPO roofing systems may be a less conventional choice for UK specifiers at the moment, but specifiers should work with trusted supply chain partners to understand the benefits of the various roofing systems available.

You can speak to our team today and explore the potential of TPO as a potential new option that might meet your project requirements, particularly for larger roofs.

Your Flat Roof Guide Summary

A flat roof offers numerous advantages, including space utilisation, energy efficiency, and cost-effectiveness and when installed properly, with regular maintenance, they can last over 50 years.

Understanding the different types of flat roofs and common issues they may face, will allow you to make an informed decision and enjoy the benefits of a flat roof for many years to come.

Need More Information?

We hope our guide to flat roof solutions and systems has given you plenty of information to get started on your project, but if you have any further questions or need assistance with your flat roof project, don't hesitate to reach out to contact our team for expert advice and services.

Alternatively, you can view our service portal for helpful downloads, videos and installation instructions for our products.