Silicone Roof Coatings: Are They Right for Your Roof? A Comprehensive Analysis

silicone roof coating vs elastomeric

Is the roof of your building showing signs of age, yet remains in a serviceable condition? If so, looking into a silicone roof coating system as a practical maintenance option to extend the life and avoid roof replacement is viable. This process applies a silicone-based elastomeric protective roof coating directly onto your existing roof. The result is a solid, water-resistant cover that can seal surface imperfections and wear areas in the existing roof, shielding your roof from leaks and weather damage. Silicone coatings are also known for their ability to reflect damaging UV rays, which helps to keep a building cooler and can reduce energy costs.

What are Silicone Roof Coatings?

Silicone roof coatings are applied as a fluid-applied monolithic layer, either rolled or sprayed, directly onto the roof surface whether it’s metal, asphalt, modified bitumen (MBUR), asphaltic built-up (BUR), EPDM, PVC, concrete, or many other surfaces. The technique itself consists of one or two applications, with the primary purpose of applying a monolithic and uniform layer to fill surface imperfections, covering blisters, and sealing seams. Although silicone roof coating systems provide extra protection against the elements, it should be noted that it doesn’t enhance the roof’s insulative values or the underlying structure.

A benefit of silicone coatings lies in being effective in preventing leaks and reducing the impact of the sun’s harsh rays, which can degrade many roofing materials over time. Another big advantage is their ability to withstand prolonged exposure to surface water such as standing water on a roof surface. Many other materials can be damaged under these conditions, but silicone holds up well. You can learn more about the pros and cons of silicone coatings here.

Most building owners may consider silicone roofing when their roofing project is functionally sound but showing signs of age or wear. Depending on the applied coating film thickness, silicone can effectively extend the roof’s life for 10 to 20 years, if not longer. Typically, the manufacturer’s warranty terms will depend on the thickness, where historically a 20-mil thickness might get you a 10-year warranty, whereas a 30-mil layer could provide coverage for up to 20 years.

Design and Installation of Silicone Coating Systems

The installation process is fairly straightforward:

  • Infrared inspection: Since you are covering an existing system, it is important to know if moisture contamination is present in the underlying system. It begins with an infrared scan to detect any wet insulation under the roof’s membrane. Areas identified with moisture issues are removed and remediated.
  • Cleaning: The entire roof surface should be cleaned of surface contaminants that could impact adhesion. Often this will include a thorough power wash to eliminate dirt, debris, and any contaminants that could hinder the coating’s bond.
  • Priming: Though not always a necessary step, a primer may be applied to increase the silicone’s bonding with the roof surface for a more durable finish. A bond test before commencement of work is always a good idea.
  • Reinforcing seams: Before the silicone application, joints of the existing membrane are reinforced to prevent future leaks and provide a smooth application. A layer of silicone coating is applied and reinforcing fabric is immediately set into the wet coating.
  • Applying silicone: The silicone is either sprayed or rolled over the entire roof surface, thus covering all repairs and reinforced areas to form a uniform protective layer. Checking the film thickness during application with a wet film gauge is always recommended.
  • Final observation and Manufacturer’s warranties: After the application and cure times, a final check is conducted by an independent inspector or a manufacturer’s representative to confirm that all necessary repairs were made correctly and the silicone layer is of adequate thickness. Following approval, any applicable manufacturer’s warranties would be issued.

Are Silicone Roof Coatings the Best Choice for Your Building?

Before you invest in a silicone roof coating system, ask the following questions to make sure you are making an informed decision regarding silicone roof coating versus other elastomeric roof coatings or acrylic roof coatings.

What is the Current Condition of My Roof?

Silicone coatings are excellent for existing roofs that are functionally sound but might need protection against isolated leaks and weather elements. If your roof has extensive damage or deteriorated areas, repairs might be necessary before applying a roof coating.

Check for visible signs of wear and tear such as cracks, tears, blisters, or bald spots (areas where roofing surfacing has worn away). These issues are common in aged roofs and can compromise the effectiveness of any new coating. Areas of standing water indicate improper drainage or sagging in the roof structure, which might also need correction before applying a silicone coating system to an existing membrane roof system.

Have you checked the condition of your roof deck and joists? If the supporting structure of the roof (deck and joists) is solid and free of rot or corrosion, unlikely there will be any structural repairs needed. But weak structural elements may need to be repaired or replaced to maintain proper slope and drainage.  As with any recovery system, the additional weight load (dead load) must be considered in the safety factor of the roof deck. If the roof has undergone previous repairs, evaluate the quality of these fixes to see if any additional work is needed before the commencement of any work.

What Type of Roof Do I Have?

Even though silicone can theoretically adhere to a wide variety of materials, how it performs can depend on the type of substrate. Silicone coatings are designed to adhere best to minimal or low-slope roofing materials such as metal, built-up roofs (BUR), modified built-up roofs (MBUR), and many single-ply membrane types.

In the design for steep-sloped roof situations, the use of fluid-applied coatings can be limited. Asphalt shingle roofs, like many lapping and not sealed systems, are not an ideal surface for silicone roof coating systems. In fact, roof coating systems are rarely an optimal choice for these types of roof conditions. The underlying material can impact how long the silicone coating may perform. For instance, silicone might extend the life of an aging EPDM roof significantly, but on a newer, already highly durable metal roof, the immediate benefits might be less impactful.

Moreover, different materials commonly require different levels of preparation before applying a silicone coating. The labor associated with roof cleaning and preparation can affect the overall installed cost. Silicone application on a smooth, clean low-sloped roof situation might be inexpensive; in contrast, a heavily textured surface might need extensive cleaning which could make the project more complex and costly.

What are the Weather Conditions in My Area?

If your building is located in a region with high levels of sunlight and UV radiation, silicone roof coatings could be a valuable investment. Silicone excels at resisting UV light, which prevents the roofing materials beneath from continual weathering over time. This can stabilize a roof’s condition and reduce the need for frequent maintenance or roof replacements.

Silicone coatings are also well-suited for areas with dramatic temperature fluctuations. They’re able to withstand extreme heat without deteriorating and remain flexible in cold temperatures. If you want to prevent your roof from cracking or sustaining damage due to the cold, silicone can be an effective option for this environment.

The same goes for areas prone to heavy rainfall; the low permeable properties of silicone coatings are well-documented. They form a monolithic, water-resistant layer that effectively prevents moisture and water penetration. This is especially beneficial for roof conditions that lack sufficient slope to effectively drain surface water from the roof surface. Silicone maintains stable even when submerged in standing water, a situation that can compromise other types of roof coatings.

Moreover, silicone is highly resistant to humidity and salt spray, making it an excellent choice for coastal areas. These environments can accelerate the degradation of conventional roofing materials due to the continually salty and moist air. Silicone’s resistant nature to these elements helps prolong the roof’s lifespan.

What is Inside My Building?

When a building contains temperature-sensitive operations, like data centers, manufacturing processes that rely on heat-sensitive materials, or products that require specific climate conditions, you may need to consider the thermal-resistant properties of your roof assembly.

Silicone roof coatings though not thermally enhancing, are known to increase emissivity by reducing the amount of heat absorbed by the roof from sunlight. This reflective capability can help maintain a more stable and cooler indoor environment, preventing equipment from overheating and minimizing the load on air conditioning systems.

If the facility’s interior is prone to moisture issues or contains moisture-sensitive materials, it is important that the roof remains completely watertight. A properly installed silicone roof coating system can create a monolithic barrier that protects against leaks and protects assets inside the building from water damage.

What Environmental Regulations Must I Comply With?

Check if there are specific environmental regulations in your area that might impact the use of a roof system and roof coatings. States have varying policies and regulations that govern air quality, chemical use, waste management, and the types of materials and substances that can be used in construction.

In California for example, the California Air Resources Board (CARB) sets clear volatile organic compound (VOC) limits to lower the levels of pollutants released into the air. These regulations are some of the strictest in the United States and influence the formulation of products sold in the state. Silicone roof coatings can be a favored choice in these regulated environments because of their lower VOC levels compared to other asphalt-based, or higher VOC solvent-based coatings.

Using silicone roof coatings can help streamline an approval process if they’re recognized in your area for their historical and environmental benefits. If your organization has “green goals” or if the building needs to meet LEED, BREEAM, or Green Star certification standards, choosing silicone may assist in achieving these objectives. They not only help reduce energy consumption by reflecting UV rays and decreasing cooling needs but also limit the frequency of re-roofing and associated waste.

Polyglass: A Dependable Choice for Roof Protection

Breathe new life into your roof with Polyglass silicone coatings. Choose Polybrite 90 for a high-solid, durable layer that combats UV rays and weather challenges, or Polybrite 95 for its solvent-based formula, which offers maximum water resistance and helps control heating and cooling costs. Explore our complete range of silicone roofing systems to place your order.