Understanding Modified Bitumen Membranes to Ensure Successful Cold Weather Application

As the Winter season approaches, applying modified bitumen roofing systems can present unique challenges. The choice of modifiers, reinforcements, and application methods becomes critical, varying based on temperature and climate conditions. A comprehensive understanding of modified bitumen roofing products and their application requirements is crucial for the successful installation of a modified bitumen roofing system, ensuring a durable and sustainable roof in the long run.

Also Read: Excellence in Roofing: Look to Modified Bitumen Membranes

Modifiers in Asphalt

When considering cold weather applications, selecting the right type of modified bituminous membrane is a primary consideration. While users might perceive mod-bit membranes as uniform, there are significant differences and variables among products. A cursory search on manufacturer websites will reveal a plethora of results.

Despite adhering to industry standards like applicable ASTM standards, unique qualities may exist among products, and not all may be suitable for specific conditions, including climatic factors. So, what’s the optimal choice for winter installations?

Types of Asphalt Modifiers: The two most frequently employed asphalt modifiers in modified bitumen membranes are Atactic-Polypropylene (APP) and Styrene-Butadiene-Styrene (SBS).

APP modified bitumen roofing: APP, a “plastic-like” polymer modifier, boasts a higher softening point, providing inherent UV and weathering resistance, making it a durable compound. Typically recommended for more southern climates.

In addition to roofing applications, APP-modified bitumen roofing systems find versatile use in various construction and landscaping projects, providing durable roofing for a range of building types, including:

  • Hospitals
  • Schools
  • Hotels
  • Sporting Arenas, and more.

SBS modified bitumen roofing: SBS, a softer and more malleable modifier, offers greater flexibility and compound memory. Its suitability is often recommended for more northern climates due to enhanced low-temperature flexibility.

Whether you’re involved in a commercial, industrial, or residential project, Styrene-Butadiene-Styrene membranes (SBS) provide superior weather protection for low-slope roofs compared to traditional asphalt built-up roofing systems and best for northern climates due to their greater low-temperature flexibility.


Initially dominated by fiberglass reinforcements, modified bitumen membranes have evolved to offer a diverse range of products categorized into three main reinforcement types, each with distinct physical and performance characteristics.

Polyester: Featuring longer bonder strands of polyester fiber, it provides durability, resistance to puncture, and greater elongation, particularly helpful during building movement and cycling.

Fiberglass: With shorter fibers in a rigid binder, it offers higher tensile strength due to its more rigid nature. Non-flammable and resistant to heat and fire.

Composite: Combining fibers of both polyester and fiberglass, these reinforcements offer unique strength and flexibility properties, albeit at a higher product cost.

Methods of Modified Bitumen Membrane Roof Application

Self-Adhered (SA): These membranes, commonly known as SA membranes, have a specialized self-adhesive compound on the bottom side, making them quick and easy to install. No additional products, such as torches or adhesives, are required.

Cold/Hot Applied: These membranes feature a sanded or similar aggregate bottom and rely on hot asphalt or cold-applied adhesives for bonding. Unique climate restrictions apply, affecting the curing process.

Heat-Welded: These membranes bond using the heat of a torch or similar tool to soften or melt the bottom side, creating a secure bond upon cooling.

Polyglass Polar Product Line

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Tailored for harsh weather conditions, Polyglass’ Polar products are designed for installation in cooler climates, typical of winter. Elastoflex SA V Polar Base and Elastoflex SA P Polar Cap SBS membranes cater specifically to temperature ranges from 25°F to 60°F and -4°C to -16ºC. Utilizing ADESO Dual-Compound self-adhered technology, a high-quality SBS-modified asphalt compound is applied on the top layer, with an aggressive self-adhesive on the bottom side of the reinforcement.

The polar versions of the SA base and cap sheet consist of a fiberglass-reinforced base sheet and a polyester-reinforced cap sheet, offering desired tensile, tear, and elongation properties to withstand harsh conditions. Like other Polyglass membrane systems, these cold-weather versions undergo rigorous testing, providing an extended manufacturer’s warranty of up to 20 years.

A comprehensive understanding of modified bitumen products, including modifiers, reinforcements, and application methods, is crucial for ensuring successful roof installations in cold weather conditions. Always consult with the manufacturer before any installation for thorough and professional guidance on all your commercial roofing systems.

Also Read: Modified Bitumen: The Ultimate Versatile Solution for Building Roofs

About Polyglass

Polyglass U.S.A., Inc. stands as a prominent manufacturer specializing in roofing and waterproofing systems. Renowned for its self-adhered modified bitumen roofing systems, which leverage the patented ADESO® Technology and CURE Technology®, Polyglass also offers a comprehensive range of premium roof coatings and roof maintenance systems. As an ISO 9001:2015 certified company, Polyglass is committed to delivering quality products and enhancing value through continuous innovation.

Are you planning a cold weather project? Connect with Polyglass to explore the Polar product line.

Roofing season is officially extended!