How Do Urethane Roof Coatings Work?

Feb 2, 2023Blog, Denver, Roof Coating, Urethane

Urethane roof coatings (more commonly known as polyurethane roof coatings) are among the strongest and most durable elastomeric coatings available in the industry. They are most commonly used for sprayed-in-place polyurethane foam insulation as well as other commercial roofing substrates including modified bitumen, single-ply, EPDM, smooth/gravel BUR, and concrete roof decks.

There are some important factors to consider when it comes to choosing this particular chemistry. Below, we highlight some key strengths and weaknesses of urethane coatings.

Why Choose Urethane?

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Urethanes offer best-in-class tensile strength, making them ideal for protection against extreme weather, moisture intrusion, and foot traffic. At the same time, urethanes are flexible. They can handle the frequent expansion and contraction of a roof’s surface in hot and cold climates.

Urethanes are versatile. They can be sprayed or rolled and adhere to a wide variety of roof substrates. Urethane roof coatings are available in two product types, aliphatic and aromatic. Together, these products form a base coat and a topcoat to increase durability and reflectivity. When combined, these coats also allow the urethane coating to stay cleaner and hold color better than other roof coating solutions.

Urethanes are UV resistant. A reflective aliphatic topcoat reflects the sun’s rays to help building owners save money on heating/cooling costs

Urethane Roof Coating Benefits

Is a urethane roof coating suitable for restoring your low-slope roof? Learn more about the benefits of urethane roof coatings and reach out to your local roofing contractor. Our knowledgeable boots-on-the-ground crew can help you select the best coating for your situation. Request a free roof consultation today.

  • Aliphatic, Aromatic, Or Both. Each type of urethane coating is best suited for a specific environment and application. Aromatic is generally the base coat, and aliphatic is the topcoat. Aliphatic offers greater UV protection and retains color for a long time. Together, these urethane coatings provide a total waterproofing solution.
  • Exceptionally Strong. Few coatings compare to urethane when it comes to durability and strength. Urethane is more resistant to impacts, moisture, and thermal movement.
  • Adheres To Almost Any Substrate. Unlike some other roof coatings, urethane coatings are versatile enough for application on nearly any substrate or roof—sloped or flat, textured or smooth. Some contractors will even use urethane as a base coat for silicone roof coatings.
  • Highly Reflective & UV Stable. A reflective aliphatic urethane topcoat helps building owners save money on heating and cooling costs by reflecting the sun’s rays instead of absorbing them. Urethane’s reflective nature supports savings no matter the season, thanks to optimal UV resistance and insulation.
  • Aesthetically Pleasing. An aliphatic urethane topcoat resists dirt pickup and won’t change color because of UV damage. You can count on urethane to look good and stay that way.

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Urethane Roof Coating Drawbacks

  • Produces a Strong Odor. A polyurethane roof coating emits a strong, xylene-based odor. While this odorous vapor is not harmful, it can be quite unpleasant for a building’s occupants. For buildings that have a fresh air intake HVAC system, we recommended it be set to recirculate air from within the building, or turned off completely during the installation process.
  • Challenging to Spray. As with any solvent-based coating, urethane roof coatings can be challenging to spray and difficult on hydraulic spray equipment. Issues during the installation process are less likely to occur if the spray equipment is properly cleaned and maintained.
  • Shorter Shelf Life. Single-component urethane coatings are constantly curing—even in the pail. Plural-component urethane coatings will not cure until mixed.


When it comes to the suitability and performance of a roof coating, it’s important to understand the strengths and weaknesses of the chemistry. Urethane roof coatings are a highly effective roofing solution. There are a number of key factors to consider when it comes to choosing the best urethane roof coating system for a commercial roofing environment.

Want to know if a urethane roofing system is right for your commercial facility? Call to schedule a free roof inspection with Denver Roof Coatings today.