Roofing Flux

By K. Snipes

Edited by Ashley Fogarty

What is Roofing Flux?

Roofing flux is a heavy, viscous petroleum product used primarily in the production of roofing materials. It serves as the base ingredient in liquid asphalt and bitumen blends that form waterproof membranes, sealants, and industrial coatings. Roofing flux is produced during the final stage of petroleum refining, after lighter fractions have been removed, leaving a dense black residue well suited for waterproofing applications. Because of its flexibility, durability, and cost efficiency, roofing flux plays a critical role in the roofing and construction industries.

Import Quantities to the Port of Baltimore

In 2024, the Port of Baltimore received 15 shipments of roofing flux, all originating in Canada. The material was delivered to asphalt terminals and blending facilities that supply roofing manufacturers throughout Maryland and the Mid-Atlantic region. Major recipients included Bitumar USA and Irving Oil.

The shipments totaled 253,288,791 pounds, or 126,644 U.S. tons. Bills of lading list a combined total of approximately 700,000 barrels of flux. When applied as a liquid roofing material, that volume could cover roughly 300,000 to 600,000 average residential rooftops.

Roofing flux is a refinery-produced asphalt base material. Through additional processing—such as air blowing and polymer modification—it becomes the bitumen used in waterproofing membranes like those installed on commercial roofs. ( Photo by M. Moradi (1985), Torch-on bitumen-based waterproofing membrane, Tehran, Iran. Wikimedia Commons, CC BY-SA 4.0).

Bitumar established its U.S. head office and a major operations hub in Baltimore in 1999, selecting Baltimore for its direct access to the Port and major transportation corridors. The facility began operations in 2000, initially producing liquid asphalt for the roofing and shingle sectors. In 2007, the site expanded to manufacture a full range of asphalt products for both roofing and paving markets. Today, the Baltimore facility produces paving asphalt graded for specific climates and traffic conditions, industrial asphalt, and roofing asphalt. Baltimore remains a central node in Bitumar’s North American distribution network.

How It Is Shipped

Roofing flux is transported in liquid form. Due to its thick consistency, it must be maintained at elevated temperatures—typically above 300°F—during transit. Heated product tankers are used to move this cargo. These vessels are equipped with insulated tanks, onboard heating systems, and safety features designed to prevent leaks or thermal hazards. Upon arrival at the port, the material is transferred into heated storage tanks before being distributed by rail or truck to regional facilities.

Uses of Roofing Flux

Roofing flux forms the base of rolled roofing sheets, roof sealants, and liquid-applied waterproof coatings used on commercial and industrial buildings. When blended with aggregates and modifiers, it contributes to asphaltic materials used for roads and parking surfaces. Its durability and resistance to water make it indispensable in modern construction.

Environmental and Economic Importance

Asphalt-based roofing materials can be recycled and reprocessed, reducing waste and conserving petroleum resources. The Port of Baltimore’s handling of roofing flux underscores its importance to Maryland’s construction and infrastructure sectors. The port’s integrated marine, rail, and trucking connections allow this material to move efficiently from vessel to production facility, supporting regional industry and employment.