Flexible Roofing – Roofing with Bitumen Shingles

Structure of Flexible Roofing

The base of flexible roofing consists of flat sheets with decorative cutouts on one edge. These sheets, known as shingles, vary in size depending on the manufacturer, but most commonly they are 100 cm wide and 30–35 cm high. The excellent performance characteristics of modern flexible roofing are due to its multi-layer structure.

The foundation of any flexible shingle is a layer of glass fiber or organic cellulose, impregnated with a special bitumen compound. To enhance strength and resistance to deformation while maintaining flexibility, various polymers (plasticizers) are added to the bitumen. The top layer of flexible roofing is colored stone chips – slate, basalt, or mineral granules, offering a wide variety of color and tone combinations for the roof.

The bottom layer is self-adhesive, and together with special galvanized roofing nails, it ensures reliable fixation of shingles to the roof base. When heated by sunlight, individual shingles bond tightly together and adhere firmly to the base.

To achieve the desired decorative effect, shingles are laid in a pattern resembling fish scales. A protective film applied to the adhesive base prevents sticking during transport and is easily removed during installation.

Advantages of Flexible Roofing

As a modern, highly advanced roofing material, flexible roofing offers undeniable benefits that largely explain its growing popularity. In addition to the long service life typical of most modern roofing materials—up to fifty years—bitumen flexible shingles:

• Have relatively low weight, so they do not require additional reinforcement of the house’s load-bearing structure or truss system;
• Are resistant to moisture absorption and accumulation;
• Due to their flexibility, are ideal for complex roof geometries;
• Offer a vast selection in color palette, shapes, and patterns;
• Protect against UV radiation and do not fade in sunlight due to internally colored granules;
• Have a wide operating temperature range (from -60 °C to +120 °C);
• Resistant even to sudden temperature changes thanks to their multi-layer structure;
• Not prone to corrosion or rot;
• Resist strong wind gusts due to absence of a sail effect;
• Do not require additional sound insulation materials;
• Reduce construction costs due to minimal waste;
• Are electrical insulators, allowing installation without a lightning rod.

Disadvantages of Flexible Roofing

Like any other roofing material, flexible roofing has certain drawbacks, mainly related to installation. For instance, installation of bitumen shingles should not be performed in sub-zero temperatures.

This limitation arises because frost negatively affects the adhesive layer that holds the shingles in place. This issue can be overcome by using a hot air gun (construction hair dryer) during installation, but this complicates and slows down the process.

A second notable feature—sometimes considered a drawback—is the need for a high-quality, solid base. This is typically made from moisture-resistant plywood or uniformly thick planed wood, installed over the roof battens. Given that roof areas are typically large, this increases material, labor, and time costs.

Flexible roofing also demands high standards of vapor barrier integrity. Otherwise, water vapor may penetrate the roof insulation and accumulate inside, as the high impermeability of bitumen shingles prevents natural evaporation.

Finally, a drawback is that damage to one or several shingles often requires replacing not only the damaged ones but the entire adjacent section.