Is silicone roof coating more waterproof? Why is acrylic roof coating so cheap yet rarely used for flat roofs? If you’re choosing the roof coating for your project, you might have many questions about these two types of roof coatings. As elastomeric roof coatings, they each have their own pros and cons. This article will show their differences, hopefully helping you make a better choice.
The Difference between Silicone Roof Coating and Acrylic Roof Coating
Cost and Lifespan
Acrylic roof coatings are cheaper than silicone roof coatings, but the protective film formed by silicone roof coatings is more durable. Over time, all roof coatings degrade, but acrylic roof coatings degrade more quickly. The film they form after drying gradually wears down and powders until it eventually loses its effectiveness.
Generally speaking, a successful application of acrylic roof coating can provide 5-7 years of protection for the roof, while silicone roof coatings last even longer, typically 10-20 years. High-quality 100% silicone roof coatings, when properly applied and maintained, can even last for more than 20 years.
If you have a limited budget or only need it for short-term use, you can choose acrylic roof coatings, which have a lower initial price. But if it won’t be a significant financial burden, choosing durable silicone roof coatings will save you a lot on long-term maintenance costs.
Weather Resistance
Silicone roof coatings undoubtedly have better weather resistance than acrylic roof coatings. Silicone roof coatings are more resistant to long-term sun exposure. Their stable molecular structure is less susceptible to UV damage, which means the coating is less likely to discolor or become brittle when exposed to sunlight. Acrylic coatings are more likely to lose their protective properties under intense UV.
Even when faced with extreme changes in outdoor environmental conditions, silicone roof coatings can function normally with minimal impact. This is reflected not only in the fact that silicone roof coatings can adapt to a wider temperature range, but also in their greater resistance to cracking or damage when subjected to extreme temperature changes.
In addition, they perform better at low temperatures, being less prone to brittleness and possessing greater resistance to snow load. Acrylic roof coatings have a shorter lifespan when exposed to low temperatures, and their properties, such as flexibility, can also be altered.
Water Resistance
If your project involves a flat-roofed commercial building, then water accumulation on the roof will undoubtedly be a headache, and silicone roof coatings are the expert solution for preventing this issue.
Silicone roof coatings have excellent waterproofing capabilities. This reliable, seamless coating keeps water on the surface, allowing it to evaporate naturally. When applied correctly, it’s difficult for standing water to penetrate the coating and seep into the building structure, preventing customer complaints or safety hazards caused by ceiling leaks.
On the other hand, it also presents another problem: the surface of the coating formed by silicone roof paint becomes very smooth when wet. If you want the roof coated with silicone roof coating to still be walkable, you can add some sand to the coating.
Acrylic roof coating is a water-based coating, so it breaks down faster in environments with prolonged water exposure, making it unsuitable for flat roofs.
Reflectivity
Under ideal conditions, acrylic and silicone roof coatings have similar thermal and UV reflectivity, both in the range of 80-90%. This means they both have excellent resistance to UV and the ability to reflect infrared radiation, allowing your building to absorb less heat from the sun.
During a hot summer with intense sunlight, high-reflectivity coatings can lower the roof temperature, saving your money and energy on air conditioning, thus achieving energy conservation and environmental protection.
As time goes on, the reflectivity of silicone roof coatings decreases. This is not due to aging, but mainly because roofs treated with silicone roof coatings are prone to accumulating dirt. To maintain good reflectivity, silicone roof coatings need to be cleaned periodically.
Suitable Roof Types
Silicone roof coatings have good adhesion to a variety of roofing materials, but generally speaking, they are a little inferior to acrylic roof coatings. They perform well on roofs made of the following materials:
- Metal
- Multi-layer asphalt
- Modified bitumen
- Concrete
When acrylic roof coatings are used on metal roofs, they also provide protection against rust.
They can also be applied to the following materials with the use of primers or other treatments:
- EPDM
- TPO
- PVC
- Sprayed polyurethane foam (SPF)
In addition, silicone roof coatings, once dry, have a certain degree of flexibility, allowing them to effectively withstand thermal expansion and contraction or movement of the underlying material.
Construction Difficulty
Silicone roof coatings require specialized application equipment, which may increase costs to some extent. Acrylic roof coatings are easier to apply, often requiring only tools such as brushes and spray guns for application.
Construction Environment Requirements
These two types of coatings have quite different requirements regarding the application environment. Simply put, silicone roof coatings have more lenient requirements for the construction environment, while acrylic roof coatings have quite strict requirements.
Silicone Roof Coatings: Lower Environmental Requirements for Construction
One reason for this difference is that they are dissolved in different liquids. Silicone roof coatings are solvent-based materials that don’t easily freeze at low temperatures, allowing them to be applied in relatively cold weather
What’s more, silicone roof coatings have a high effective content and usually only require a single coat on the roof. They also cure in damp weather, reducing dependence on weather conditions, which allows your project to proceed more smoothly and provides greater tolerance for unforeseen circumstances.
Acrylic Roof Coatings: Strict Environmental Requirements for Construction
Because of containing water, acrylic roof coatings are more prone to freezing in cold conditions and therefore can only be used in warmer weather. Generally, acrylic roof coatings are only considered for use when the temperature is above 10°C.
As a water-based material, acrylic roof coatings have a solid content of approximately 55%, meaning that workers need to apply 2-4 layers of coating to achieve effective protection. This results in a long drying time.
Moreover, acrylic roof coatings need to be applied in a dry environment. Humid air or rain will severely affect the curing process and significantly reduce its protective effect. This requires you to accurately assess the weather conditions before application.
Environmental Friendliness
Because acrylic roof coatings are water-based materials, they are environmentally friendly.
Traditional silicone roof coatings may not be as environmentally friendly as acrylic coatings, but manufacturers have now developed many formulations with very low or almost zero solvent content, and include very few volatile organic compounds (VOCs). Therefore, by choosing a high-solids silicone roof coating, it can also meet your expectations for environmental friendliness in your project.
Maintenance and Replacement
Silicone Roof Coatings: Require Rinsing and Maintenance, and Recoating Is Difficult
Silicone roof coatings provide excellent resistance to mold and mildew that thrive in damp environments. However, because they can heap up dirt and debris, you need to clean them periodically to maintain optimal protection. You can easily clean them using a pressure water gun. If the coating is damaged, you can repair it by cleaning the surface and allowing it to dry before applying the same type of coating to fill in the damaged area.
But recoating a silicone roof coating may not be so easy. Aged or severely damaged silicone coatings require thorough cleaning with solvents or denatured alcohol. Sometimes, a primer is also needed before applying a new silicone roof coating.
Acrylic Roof Coatings: Easy to Maintain and Recoat, But Require More Frequent Recoating
Acrylic roof coatings may develop mold after long-term use, but fortunately, cleaning and recoating acrylic roof coatings is much easier. They are easy to clean, requiring only water.
But if constantly submerged in water or covered in snow for extended periods, the coating will gradually absorb moisture and lose its effectiveness, further increasing the frequency of recoating. If used in areas with standing water frequently, the costs involved will increase even further.
Aesthetics
Silicone roof coatings prioritize practicality, so they don’t come in many colors. The most common colors are white and gray. After long-term use, if not cleaned regularly, roofs coated with silicone paint tend to become quite dirty.
In contrast, acrylic roof coatings have a much wider variety of colors, and dirt and grime don’t heap up on them as easily.
Recommended Application Scenarios of Silicone Roof Coating
Due to the properties of silicone roof coatings, they are more recommended for the following situations:
- Roofs prone to water accumulation, such as flat roofs
- Regions with heavy rainfall or consistently high humidity
- Regions with cold climates where snow easily accumulates on the roof
- Focusing on long-term benefits and durability
Recommended Application Scenarios of Acrylic Roof Coating
Acrylic roof coatings are more cost-effective if used in the following situations:
- The roof has good drainage performance
- The roof has a steep slope
- Metal roofing
- Warm and dry area
- Focus on the visual appearance of the roof
FAQ
What Other Types of Roof Coatings Are Available?
- Polyurethane coatings. It has excellent physical and mechanical properties and can withstand impact and trampling.
- Butyl Rubber. It has excellent flexibility, elasticity, and sealing properties.
- Asphalt Roof Coatings. It’s very cheap and is most commonly used on the roofs of old buildings.
Can I Apply a Silicone Coating over an Acrylic Roof Coating?
No, it’s recommended to use the same type of silicone roof coating for recoating. Applying a different type of roof coating directly over the existing silicone coating may lead to adhesion problems.
If you want to apply an acrylic roof coating over another type of coating, it’s best to apply a primer first and perform a compatibility test on a small area to avoid potential financial losses.
How to Apply Silicone Roof Coating？
Step 1: The roof condition should be assessed, and any necessary repairs should be made. Fill any cracks in the surface with sealant or other appropriate materials to create a smooth surface.
Step 2:Wash the roof with a high-pressure washer. If there is stubborn dirt, a cleaning agent can be used.
Step 3: Some roofs may require an adhesion test to determine if an additional primer coat is needed.
Step 4: Once completely dry, apply the coating evenly to the roof surface using a long-handled roller or brush. Some silicone roof coatings may require mixing two components beforehand.
Step 5: Wait for the silicone coating to completely dry and cure.
Can I Use Silicone And Acrylic Roof Coatings To Meet LEED and Cool Roof?
Silicone and acrylic roof coatings can help your project meet LEED and Cool Roof requirements. These coatings reduce air conditioning use and mitigate the urban heat island effect by increasing both short-term and long-term roof reflectivity.
Final Thoughts
Silicone roof coatings and acrylic roof coatings are bestl choices for different situations, and you can choose the one that better suits your needs. If you’d like to learn more about the details of silicone roof coatings, or if you have any further questions, please click Legensilico to get more information!
