Roofer appying urethane roof coating with tank spreader

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.

The Advantages

Aliphatic vs. Aromatic

There are two types of urethane roof coating: aliphatic and aromatic. Each type is best suited for specific roofing environments and applications.

Aliphatic urethane coatings are UV stable, hold color longer, resist dirt pick-up, and are typically used as a top coat. Aromatic urethane coatings are not as UV stable, cost less, and are most commonly used as a base coat in most systems.

Durability & Flexibility

Polyurethane roof coating systems form an incredibly durable and flexible monolithic membrane layer. They can effectively withstand the daily expansion and contraction (thermal movement) of roof structures as well as the damaging effects of ponding water.

They are also more impact-resistant than other coating materials, making them ideal for use on roofs with high-traffic areas.

Adhesion Qualities

Urethane coatings are perhaps best known for having outstanding adhesion. They will fully adhere to most conventional commercial roofing substrates including metal, modified bitumen, built-up roofs, spray polyurethane foam, concrete roof deck, EPDM, TPO, and other single-ply membranes.

UV Stability

Urethane roof coating systems are highly reflective and UV stable. This means building owners and facility managers can save money by reducing cooling costs during the hot summer months. Minimizing the sun’s impact on the roofing surface not only helps to sustain lower energy costs, but it also reduces internal building temperatures and prolongs roof life.

VIDEO: Click here to watch a single-wide tank spreader applying a urethane roof coating.

The Disadvantages

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.

PRO TIP: Click here to view a detailed xylene vapor analysis report for one of our most popular polyurethane roof coating products.

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 which will not cure until mixed.

Urethane Roof Coating Products We Provide

Aliphatic Urethane 510

Aliphatic Urethane 510 is primarily used as a top coat in our hybrid-urethane systems. This highly-reflective polymer creates a durable, seamless, and flexible membrane that will allow for normal expansion and contraction (thermal movement) of the roof structure. It also provides excellent UV protection and offers increased resistance to moisture penetration through its lower moisture vapor permeability values.

Learn more about Aliphatic Urethane 510

Aromatic Urethane 520

Aromatic Urethane 520 is a highly-durable polyurethane roof coating that primarily serves as the foundation coating for our Ure-A-Sil System. It is also the core component of our standard urethane system.

This silver-colored coating shares some of the same physical properties as its bright-white aliphatic counterpart, but it’s not quite as reflective or UV stable. This makes it better suited for use a base coat in most liquid-applied roof restoration systems.

Learn more about Aromatic Urethane 520


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’s 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? Click here to schedule a free roof inspection with an American WeatherStar Approved Contractor.