The evolution and history of felt roofing

Felt roofing has long been a valued resource in the world of flat roofing. It has always been known for its durability, versatility and has provided solutions for both residential and commercial properties for over a century with a history that can traced back to the industrial revolution. 

The actual origins of felt roofing date back to the late 19th century, a time when the rapid growth of cities and industries demanded affordable and effective roofing for flat structures. Early systems were composed of alternating layers of tar and roofing felt. These materials were abundant, cheap and installed by many people. By layering these components, builders achieved a watertight barrier that could endure harsh weather conditions and prolonged exposure to the elements.

One of the key drivers of growth was its compatibility with flat-roofed buildings, which were gaining popularity due to their efficient use of space and suitability for urban environments. Flat roofs allowed for practical designs in factories, warehouses and commercial structures where pitched roofs would be impractical or too costly. During this period, the technology was rudimentary. Materials such as coal tar pitch and untreated organic felt were used, but these early systems were prone to cracking, blistering, and degrading under prolonged UV exposure. Despite these limitations, felt gained widespread traction as the best available solution for flat roofs at the time.

Advancements in materials and techniques

The mid-20th century saw advancements in built-up roofing technology. One major development was the transition from coal tar to bitumen as the primary binding material. It offered several advantages - being less toxic, more flexible and easier to work with compared to coal tar. This greatly improved the lifespan and performance of felt roofing, especially in varying temperature conditions. Another key advancement was the introduction of fibreglass felt. Unlike organic felt, which was prone to absorbing water and rotting, fibreglass did not rot and thereby provided a felt that could in general outperform the early membranes

By the 1960s and 70s, felt was the go-to choice for flat-roofed buildings. The introduction of blinding the top layer felt with stone/ gravel provided the felt waterproofing with a fire rating, provided UV protection and ballasted the roof thereby extending its lifespan. However, while felt gained popularity, it was not without its challenges. Installing such a roof was labour-intensive and required skilled contractors to achieve proper adhesion and layering. The use of bitumen which needed to be melted in a boiler and poured during installation process, posed safety risks, including burns and inhalation of toxic fumes. 

By the late 20th century, these challenges led to the emergence of alternative flat roofing solutions such as single-ply membranes (EPDM, TPO, and PVC), which promised often easier installation and reduced maintenance. However, rather than fading into obscurity, felt evolved to address these shortcomings. 
One breakthroughs was the introduction of modified bitumen. This material combines bitumen with modifiers like SBS (styrene-butadiene-styrene) or APP (atactic polypropylene), which enhance flexibility, UV protection and improved performance with extreme temperatures. Modified bitumen is applied in sheets using safe to torch methodology. These advances again improved the expected life from these membranes.

Cold-applied BUR systems

More recently, the development of self-adhesive felts by companies such as Proteus, has further transformed the roofing landscape. These felts eliminate the need for open flames or hot bitumen, making them safer and more accessible for installers. Self-adhesive systems are particularly advantageous for reducing installation risks while maintaining the layered protection that built-up roofing provides. Together, these demonstrate a clear trajectory towards improved safety, efficiency and environmental consideration in the roofing industry.
Furthermore, as sustainability has become a major focus in the roofing industry, felt has adapted to this trend. Built-up systems can now be combined with green and blue roofing solutions, such as vegetative layers that improve insulation and reduce stormwater runoff. Modern installations also prioritise energy efficiency by integrating insulation materials into each new installation or refurbishment project. 

The advancements in built-up felt roofing have continued to make it a competitive option in today’s market. With improved materials such as modified bitumen and reinforced membranes, modern systems can last 35 years or more with proper maintenance. As the roofing industry continues to innovate, the future of built-up felt roofing looks promising. Trends such as smart roofing technologies, which integrate sensors for real-time monitoring of roof conditions, are likely to further enhance the appeal of felt. Additionally, ongoing research into sustainable materials and carbon-neutral production processes could make the material a better environmental option for the future. The integration of solar panel systems with felt is another area of potential growth. With the load-bearing capacity of modern systems, they can serve as ideal bases for photovoltaic installations, helping buildings achieve energy independence.

As we can see, felt roofing has come a long way from its humble beginnings as a rudimentary tar-and-felt system. Through continuous change, it has adapted to meet the demands of modern construction while retaining its core strengths of. With advancements in materials, installation methods, it remains a relevant and viable solution for flat roofing in the 21st century.