Comparing Silicone and Urethane Commercial Roof Coatings

Jan 24, 2023Blog, Denver, Roof Coating, Silicone, Urethane

Both polyurethane and silicone are elastomeric roof coatings that are designed to stretch and contract with the movement of the roof, but there are some differences that would make one preferable to your roof over the other. Look at some of the similarities and differences between these two roof coatings in Denver and see what works best for you.

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Commonalities Between Polyurethane And Silicone Coatings


Both types of roof coatings can be applied via roller or spray application. As they are coatings both will allow you to rehabilitate an existing roof by coating overtop as opposed to having to remove the existing roof which will save time, and money, and prevent additional material from going to landfill reducing the environmental impact.

Cool Roofs

Both polyurethane and silicone coatings are highly reflective coatings that reduce a building’s cooling demand in the hotter summer months which reduces strain on the electrical grid, reducing the number of brownouts and blackouts. The greater the number of buildings with these “cool roofs” in an area the greater the reduction in outdoor air temperature of that area as these roofs reflect the sun’s rays back into the atmosphere which slows the production of ground-level ozone, otherwise known as smog.

Ponding Water

When it comes to low-slope or flat roofs both polyurethanes and silicones are excellent from a waterproofing perspective. Often there are areas that are not sloped properly to the drains which can lead to ponding water on the roof. Both polyurethanes and silicones are great with ponding water, which won’t have an effect on them, vs. acrylic coatings which are water-based and will wear down with exposure to ponding water leading to roofing failures.

Silicone Coatings

Silicone coatings are highly elastic materials that provide excellent adhesion to the existing surface. Silicone coatings have gained market share in the commercial roof market in the last decade. Silicone coatings also provide excellent ultraviolet protection in extreme temperatures and harsh environments and can resist oxidation. Silicone is available in a variety of colors and provides high reflectivity and emissivity ratings.

With silicone coatings, nothing likes to bond to silicone, not even silicone. This causes issues both from a roof replacement and a repair perspective. When the roof is at the end of its life instead of reapplying a new topcoat, you will likely need to remove the silicone membrane before you can install the new roofing system.

Another issue with silicone coatings is that they are known to be dirt magnets attracting dirt and other airborne particles. This can cause a gradual build-up on the roof that can make the coating system more susceptible to heat from the sun, and thus less reflective, which negatively impacts the advantages you would have with a “cool roof”. To get around this the roof would need to be pressure washed every six months or so.

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Polyurethane Coatings

Polyurethane coatings are used as coating applications over a variety of existing roof membranes. Polyurethane coatings provide the best rates of all coatings for impact resistance and for foot traffic. There are two types of polyurethane roof coatings: aromatic and aliphatic. These types of materials are typically used in combination with a base coat and topcoat. The base coat material is durable but does not offer high UV resistance.

Polyurethanes typically have a higher solids content than silicone roof coatings. Polyurethane is a much stronger coating and will not puncture easily if a tool is dropped or outdoor furniture is dragged across its surface. The same cannot be said of silicones which can puncture easily.

Polyurethane roofs that hit that 15 to 20-year mark their lifespan can be extended by another 15 to 20 years by the reapplication of a polyurethane top coat over top of the existing roof. Essentially, you would solvent wipe the previous polyurethane roof topcoat and then roller or spray apply the new polyurethane topcoat overtop. It also allows for very easy roof repairs if they are required.


If you are looking for the best roof coatings in Denver, look no further than Denver Roof Coatings. Our team of experts can help you find the perfect coating for your roof, whether it is a new build or a re-roof. Contact us today to learn more about our products and see how we can help you protect your roof.