Over the past five decades, modified bitumen roofing has transformed from an experimental concept into one of the prevailing commercial roofing systems in the industry. Its exceptional tensile strength, longevity, and relatively straightforward installation process have rendered it a favored roofing solution for countless projects worldwide. Yet, what precisely defines modified bitumen roofing, and what sets it apart from other roofing materials.
Embarking on an in-depth exploration of this subject, we will delve into the essence of modified bitumen roofing and its evolutionary journey, explain the various types of modified bitumen, and address numerous frequently raised queries. By doing so, we aim to equip you with the insights necessary to discern whether modified bitumen roofing systems align with the requirements of your upcoming project.
What is Modified Bitumen Roofing?
Modified bitumen is often considered the progressive relative of built-up roofing systems (BUR), which have been employed on low-slope roofs for over a century. This roofing material is crafted by blending asphalt with polymerized rubber or plastic and subsequently reinforcing it with fiberglass and/or polyester fabric mats, resulting in a resilient yet pliable waterproof membrane.
Typically utilized on low-slope commercial roofs, modified bitumen roofing can be installed in various configurations. Depending on the type and composition, these membranes may be incorporated as components of either a two-layer system or a multi-ply system.
Also Read: Excellence in Roofing: Look to Modified Bitumen Membranes
History of Modified Bitumen
Modified bitumen made its debut in commercial roofing during the mid-1960s in Europe. Before its introduction, the prevailing roofing system utilized on most commercial buildings was built-up roofing (BUR), characterized by a complex arrangement of alternating layers of asphalt and fabric, surfaced with gravel.
Although BUR had established itself as a reliable method, its weight, installation expenses, repair challenges, and susceptibility to extreme temperatures posed significant drawbacks. With modified bitumen, developers aimed to streamline the roofing process while addressing common issues associated with BUR by incorporating bitumen with polymers and reinforcing mats into a simplified membrane.
The endeavors proved fruitful. Modified bitumen offered easier installation and heightened protection compared to BUR systems, even in severe cold conditions. By 1975, modified bitumen had gained widespread adoption in the United States, gradually supplanting BUR as one of the most dependable roofing materials available today.
Methods of Applying Modified Bitumen
Normally supplied in membrane rolls, modified bitumen is applied directly to the substrate using an adhesive. The installation process may involve heat welding, cold adhesion, or, in certain instances, self-adhesion, as seen in several of Polyglass’ premium products featuring ADESO® self-adhering technology.
Additionally, mechanical attachment is a possible application method for some modified bitumen membranes. While the majority of installations require a minimum of two layers (a base layer and a cap layer), there are instances where a multi-ply system with three or more layers may be utilized.
Types of Modified Bitumen Membranes
Modified bitumen commonly falls into two main categories: APP and SBS.
APP Membranes
Often referred to as “plastic asphalt,” atactic polypropylene (APP) membranes are composed of asphalt mixed with plasticized polymers that exhibit elasticity under elevated temperatures. APP offers resistance to UV rays.
SBS Membranes
SBS, or styrene-butadiene-styrene, is akin to “elastic” or “rubberized” asphalt in the context of roofing. This membrane blends asphalt with polymerized rubber, providing natural flexibility and elasticity. SBS is an excellent choice for buildings with roofs that undergo significant expansion and contraction due to extreme temperature variations or those exposed to high winds.
What are the benefits of Modified Bitumen Roofing?
Modified bitumen roofing offers several benefits:
Durability: Modified bitumen roofs are highly durable and can withstand harsh weather conditions, including extreme temperatures, high winds, and heavy rainfall.
Flexibility: The flexibility of modified bitumen membranes allows them to expand and contract without cracking or splitting.
Weatherproofing: Modified bitumen roofing provides excellent waterproofing properties, ensuring that water does not penetrate the roof structure and cause damage to the building interior.
Longevity: With proper installation and maintenance, modified bitumen roofs can have a long service life, providing reliable protection for many years.
Energy Efficiency: Reflective coatings can be applied to modified bitumen roofs, helping to reduce heat absorption and lower cooling costs, making them energy-efficient options for buildings. Polyglass does offer a product line with a factory applied reflective surface.
Ease of Installation: Modified bitumen roofing systems are relatively easy to install compared to other roofing materials, which can help reduce installation time and labor costs.
Frequently Asked Questions
What is the typical lifespan of modified bitumen?
The average lifespan of modified bitumen roofing is approximately 20 years, potentially extending with appropriate upkeep and maintenance.
What are the application methods for modified bitumen roofing?
Modified bitumen is commonly applied through heat welding (torch), mopping in hot asphalt, cold-process adhesive, or self-adhering membranes.
How can modified bitumen roofing be repaired?
Typically, damaged sections of modified bitumen roofing are repaired by removing the affected membrane, applying a modified bitumen patch, and then sealing it to ensure protection.
What are the drawbacks of modified bitumen roofing?
Installing roofing in general including modified bitumen, requires a certain level of expertise, and there is a fire risk associated with heat welding during installation. This risk is mitigated by the use of self-adhering modified bitumen membranes, which not only streamline the process for contractors but also eliminate the need for torch application.
What advantages do self-adhered membranes offer?
As noted earlier, self-adhered modified bitumen is notably simpler to install due to the pre-applied adhesive layer. Additionally, it reduces any fire hazards linked with open-flame torching.
What is cold-applied roofing?
Cold-applied roofing involves the attachment of roof membranes using a cold-process adhesive (solvent-based) instead of heat welding.
Is it possible to install modified bitumen during cold weather conditions?
Modified bitumen installation in cold temperatures is feasible with specific considerations and precautions. Optimal outcomes are achieved by selecting roofing products specifically designed for cold-weather installation. For instance, Polyglass offers low-temperature Polar cap and base membranes tailored for use in freezing conditions.
Also Read: Understanding Modified Bitumen Membranes to Ensure Successful Cold Weather Application
Explore Polyglass’ Range of Modified Bitumen Products
Discover an extensive selection of premium modified bitumen roofing products from Polyglass designed to meet diverse application needs. Explore our range of modified bitumen offerings, and don’t forget to subscribe to our newsletter below to access additional valuable roofing insights and resources. Contact us to get started.