The evolution of low-pitched roofing

Paul Duffy, Managing Director for Onduline Building Products, explores the evolution of low-pitched roofing, the key challenges it has faced, and the innovations that are shaping its future. 

Low-pitched roofs, generally defined as having a slope of less than 20 degrees, have long been associated with architectural styles that prioritise form over function, favoured for their aesthetic appeal in modern, minimalist designs. However, the reduced angle of these roofs can come with inherent drawbacks. 

Historically, the primary challenge with low-pitched roofs has been water management. With less slope to direct water runoff, rain and snow are more likely to pool, leading to water leakage and damage. Traditional materials, particularly those designed for steeper pitches, often proved ineffective at waterproofing low-pitched roofs, resulting in costly repairs and reduced longevity. 

For much of the 20th century, material options for low-pitched roofing were limited. Asphalt shingles, clay tiles, and even thatch were not suited to the demands of shallow slopes, and flat roofing materials like tar and gravel were prone to cracking and deterioration. This further restricted the adoption of low-pitched roofs. 

Another factor contributing to the historical underutilisation of low-pitched roofs was the trade-off between aesthetics and functionality. While low-pitched roofs could lend a sleek, modern look to a building, they often required frequent maintenance and repairs to address weather-related wear.  

However, recent advancements in roofing technology have addressed many of these historical challenges. New materials offer improved waterproofing solutions, and better installation techniques have significantly enhanced the viability of low-pitched roofs. 

One of the most significant innovations driving the resurgence of low-pitched roofing is the development of advanced materials specifically designed to withstand the unique demands of shallow slopes. Modern membranes, such as single-ply systems, are highly durable, flexible, and waterproof, offering superior protection against water ingress. 

EPDM (Ethylene Propylene Diene Monomer) and TPO (Thermoplastic Polyolefin) are two examples of high-performance synthetic rubber and plastic-based materials that are now widely used in low-pitched roof applications. These materials are not only highly resistant to UV radiation, temperature fluctuations and weathering, but they also provide excellent insulation, contributing to energy efficiency in buildings. 

Furthermore, the development of sub-roof systems that combine both durability and ease of installation, such as Onduline’s ISOLINE LOW LINE solution, show how innovation is transforming this once-challenging area of roofing.  

ISOLINE LOW LINE is designed to be installed beneath any roof tile at a pitch as low as 10 degrees. The bituminous nature of the system offers superior waterproofing properties compared to traditional roofing materials, ensuring that water infiltration is prevented even under extreme weather conditions. Its compatibility with all roof tiles makes it a versatile choice for newbuilds, renovation and heritage projects. 

Improved installation techniques 

Proper installation is critical to the performance of low-pitched roofs. Modern installation techniques have significantly improved, ensuring that low-pitched roofs can be installed with the same confidence as steeper roofs. 

For instance, liquid-applied roofing systems, which involve applying a seamless membrane directly to the roof surface, eliminate the seams and joints that were traditionally weak points in roofing systems, reducing the risk of leaks and improving the roof’s overall durability. The development of self-adhering and heat-welded roofing membranes has also revolutionised installation practices. 

Refurbishment and heritage projects 

These innovations are also finding applications in refurbishments and heritage restorations. Many historical buildings feature low-pitched or even flat roofs, and preserving these structures while ensuring they meet modern building standards requires careful attention. 

In heritage projects, maintaining the visual integrity of the building is often a top priority. Clay and slate alternatives that mimic the appearance of traditional materials, while offering modern performance benefits, are helping to ensure that low-pitched roofs on historic buildings can be restored to their former glory without compromising on durability or weather resistance. 

For newbuilds, low-pitched roofs are becoming increasingly popular. The combination of sleek aesthetics, improved functionality, and the ability to incorporate sustainable technologies makes them an attractive option for specifiers seeking to create modern, minimalist and eco-friendly buildings. 

www.onduline.co.uk