Acrylic Roof Coatings vs. Silicone Coatings: What’s Better for Ponding Water?

Have a commercial roof? You may be asking yourself: which is better for ponding water: acrylic roof coatings or silicone?

We talk a lot about maintaining and repairing with the aim of keeping water out. And with good reason. Leaks can cause water damage, mold growth, failing insulation, and damaged structural materials.

A commercial building’s roof takes a beating, exposed to the elements as it is. And if it doesn’t drain properly, then your roofing materials become subject to the added stress of ponding water. A puddle after a rainstorm is common. However, standing water that lasts a few days or more could prematurely deteriorate your roof.  

Ponding Water Problems

Ponding water can also create a number of other problems for buildings. Large amounts of water sitting on your roof creates an unexpected structural load. This can damage not only your roofing membrane but could also impact the structure of your building. Furthermore, it may cause the roof to collapse.  

Usually, ponding water is simply a source of leaks as it tears down roofing seams and systems. Then, the water finds its way into your building.

Replacing your roof when only one area is experiencing ponding water is an expensive proposition. Many contractors will propose solutions like acrylic roof coatings or silicone roof coatings, but there are pros and cons to each.

 

Preventing Ponding Water Damage

The first step to avoiding ponding water damage is to prevent it from becoming a chronic problem. Maintenance staff should conduct regular roof inspections. In addition, address ponding water problems quickly once found.

A number of problems can cause ponding water. However, there are also a variety of fixes depending on how bad the ponding is and the age of your roof.

• Repitch the roof. If ponding occurs because of improper sloping or sagging, hire a contractor to repitch the roof. This option can be expensive and costly, so before you make that decision, consider other simpler fixes.
• Check drains for blockages and clogs. This is the simplest and fastest fix. If your roof drains properly, leaves or other debris could be the culprit. Check them regularly to prevent water from backing up during rain events.
• Install additional drains and crickets. Add more drainage if the ponding is caused by an aging, sagging roof. While this step is more involved than cleaning the existing drains, it’s stiller faster and cheaper than repitching your entire roof.
• Repair low points. If you’re not yet at a place where you can or need to repair the entire roof, then you may just need to repair the low points. Remove and replace damaged materials and cover them with a high-quality waterproof coating to extend the overall lifespan of your roof.

 

Which Coating to Choose: Acrylic or Silicone?

A commercial roof coating adds extra longevity to your building without the time and expense of a complete tear-off and replacement. In fact, an acrylic reinforced roof coating offers a number of benefits, including:

• Highly durable and long-lasting. Acrylic reinforced roof coatings like 720 ARC Elastahyde or 790 AFC ElastaHyde are applied with layers of polyester fabric, creating a durable barrier to protect your building from the elements.
• Energy-efficient. Acrylic roof coatings usually go on white and are highly reflective of solar energy, rather than absorbing it the way darker colored coatings and membranes do. They can also be manufactured in energy-efficient tan or gray colors that still meet the energy code requirements for a cool roof. The white, light tan or light gray options reduce the energy load in your building and save you money in cooling costs.
• Compatible with many roof systems. Products like Western Colloid’s ElastaHyde-720 and 700 EC Western White are designed to be applied over a variety of bituminous, foam, metal and gravel roofs, eliminating the need for a tear-off and replacement.

Acrylic Roof Coatings

Acrylic coatings are designed to be water-resistant and are more than capable of standing up to heavy rain, provided the roof drains properly. However, if you don’t have perfect drainage and ponding water is an ongoing issue, make sure the coatings being applied to your roof are a high-quality acrylic coating with proven ponding water performance and that they are being installed properly. 

An acrylic coating such as Elastayhyde- 720, reinforced with a layer of polyester, has been proven over and over as resistant to ponding water. The polyester in the water-based product adds strength and durability in standing water and is easily renewable. 

Silicone Roof Coatings

Silicone can be an effective solution if ponding water is an issue on a large portion of your roof or if your roof is in a wet climate. As a non-water-based product, it will stand up better over time where water collects. However, a silicone coating should never be applied to a ponding area without the proper primer. 

Silicone has a high vapor transmission rate and will not completely block moisture from penetration through to the membrane. The silicone coating itself will hold up to the ponding water but the membrane underneath may not. Silicones that aren’t reinforced with a polyester membrane are prone to stress cracks. That’s because silicone has very low tensile and tear strength.

Silicone roof coatings are a fast, easy-to-apply economic roofing solution. But not all silicone coatings are sustainable because adhesion for reapplication or repairs is questionable. 

Ensure your silicone coatings are recoatable. Many silicones are difficult to adhere to when making repairs or when it’s time for recoating to renew the warranty. Improperly installed, they can lead to premature failure that is likely to result in a roof that needs to be torn off and replaced and water damage.

What are the biggest difference between acrylic and silicone when it comes to ponding water? Acrylic coatings tend to curl up in water under certain conditions. Silicone coatings can sit in ponding water with no problem but may stress crack and allow and leaks. Silicone coatings could also pass large amounts of water vapor through to the underlying membrane without a vapor barrier primer.  

The Bottom Line

The bottom line is both types of coating benefit from polyester reinforcement. In acrylic, the polyester binds the coating to stand up to ponding water. However, silicone creates the strength it needs to handle stress from movement and prevent cracking.  

If you want the durability that comes with acrylic coatings, choose a product designed to stand up to ponding water. Options like 770 AXP ElastaHyde, which is a ponding resistant base coat, should be considered for roofs where a large percentage of the roof area has ponding water and the acrylic coating will not be reinforced.

Choose Western Colloid Acrylic Roof Coatings

If you want a proven roof coating solution that gives you durability and compatibility with other roofing systems and also provides you some peace of mind when it comes to waterproofing — then your best bet is to go with tried and true systems by a trusted manufacturer who has over 45 years of successful installations.

To help find the solution that works best for your needs and your budget, visit the Western Colloid website to schedule a complimentary consultation.