Single ply roofing systems – a sustainable alternative to metal

Hard-wearing and aesthetically pleasing, metal roof surfaces have long been a popular choice for refurbishments and new builds alike. However, these systems also include a number of potential drawbacks. Paul Martin, architectural sales manager at Langley Waterproofing Systems Ltd, looks at the use of single ply roofing systems, particularly with simulated standing seam detailing, as an alternative to metal roofing and the advantages these can offer to a wide range of projects

Specified for its durability and desirable appearance, metal roofing has been in use for hundreds of years and continues to be used for modern and heritage projects around the world.

Unfortunately, metal roofing appeals to more than just architects and building owners, with metal theft becoming an increasing issue. The costs of these thefts extend far beyond the replacement of materials, often resulting in the failure of the roof system and the potential closure of a building while the issue is dealt with.

With their comparable aesthetics, reduced risk of theft and a host of performance benefits, single ply roofing systems are increasingly being selected as alternatives to traditional metal.

Available in most RAL colours, single ply membranes can mimic the appearance of a building’s previous roof surface, making them ideal as a replacement for damaged, failing or stolen metal roofing. The systems are also available with a simulated standing seam detail, allowing architects to replicate a traditional standing seam metal appearance without any of the drawbacks associated with lead, copper or zinc.

Single ply systems often prove to be a more cost-effective alternative, consisting of a single ply cap sheet or membrane laid above insulation and a vapour control layer. Vapour control layers are installed at an early stage of a project, allowing a building to be watertight far sooner than when working with metal. Once installed, the single ply membrane provides continuous waterproofing even through awkward architectural detailing, reducing the risk of water ingress throughout a building’s lifetime.

Building owners are also understandably concerned by the risk of fire that is introduced when using some roofing systems, a worry that has been emphasised by a number of recent cases which have made headlines.

By opting for single ply systems, which offer safe, flame free installation, as well as easy maintenance and repair, architects can offer their clients the reassurance that all possible steps are being taken to ensure the safety of both the project as a whole and the roof itself.

Manufactured in a variety of roll widths and thicknesses, single ply systems offer low roof zone depth as well as speedy installation. In addition, the membranes’ flexibility simplifies the creation of architectural features such as barrel, curved or gullwing roofing, which would require the pre-bending or on-site bending of metal surfaces and increase construction times. Elements such as box guttering can also be formed easily in one continuous membrane, removing the need for installers to weld multiple joins.

For buildings where weight is an issue, single ply roofing systems are considerably lighter than their metal counterparts, allowing architects to realise their visions without being restricted by structural constraints.

In cases where environmental impact is a priority, clients can be assured that some single ply membranes are 100 per cent recyclable and don’t contain chlorine, plasticisers or heavy metals, offering an eco-friendly solution without sacrificing performance. The absence of plasticisers can also help to ensure the longevity of a roof, allowing the membrane to retain its flexibility without the risk of migration, which can lead to cracking, flaking and ultimately the failure of the roof surface.

Due to their construction, these membranes are also highly UV and root resistant, minimising the growth of algae and other micro-organisms which allows the roof to retain its appearance over the course of the building’s life. This makes single ply systems particularly useful for green roofing applications, where the membrane can be easily installed around landscape features and contours.

Whether a client’s goal is to replicate what went before, add a traditional touch to a new building or simply to keep material and construction costs low without sacrificing quality, single ply systems are a reliable and time-tested alternative to metal, and can form an essential tool in an architect’s roofing arsenal.