National Coatings Blog

This winter has been quite a wet season, bringing to light many roofing issues that have created leaks. Ponded water is one of the issues that can lead to damage if it is not properly taken care of.

What is ponded water?

The National Roofing Contractors Association (NRCA) defines ponded water as "water that remains on a roof surface longer than 48 hours after the termination of the most recent rain event.” Water that sits on your roof top for an extended amount of time can lead to blistering, delamination and peeling of the roof surface. This ultimately results in a leaking roof that is in need of repair.

What Causes Ponded Water?

Ponded water can occur on the rooftop either because of a poor slope design or drainage issues. Conducting a semi-annual roof maintenance inspection every six months helps ensures that your drains are not clogged or obstructed and they are working as expected. Roofs that have a bad slope causing rainwater to constantly pool together in a specific location will need to be fixed by a roofing professional.

Solving Ponded Water Issues

There are roof coating systems, such as the AcryShield SPF Roofing System which allows a roofing contractor to create a new custom slope directly on top of your existing roof, ensuring that the next time it rains, the water will lead to a drain. The spray polyurethane foam (SPF) used in these systems is applied heavier in areas to create an angle that draws the water towards the drain. The base coats used in the AcryShield SPF Roofing System also add additional ponded water protection as they are capable of retaining their waterproofing and superior adhesion capabilities after being submerged in water for an extended amount of time.

National Coatings has a full line of AcryShield roof coatings that provide excellent waterproofing, superior adhesion, and resistance to ponded water for almost any roofing substrate including: Asphalt, BUR, Mod Bit, TPO, PVC, EPDM, Hypalon®, Metal, SPF and Concrete roofing. If you would like more information on our base coats or roofing systems with ponded water resistance, download our FREE Product Brochure!

Ponded water resistance is the ability a roof coating can remain bonded and adhered to the roof substrate after being submersed in water for an extended period of time. The National Roofing Contractors Association (NRCA) specifically defines roof ponding as "water that remains on a roof surface longer than 48 hours after the termination of the most recent rain event". This becomes extremely important when puddles form on the rooftop due to poor slope or drainage issues. Without proper ponded water protection, your roof coating will begin blistering and peeling, causing leaks and corrosion to occur, leading to untimely roof failure.

Ponded water protection should be a necessary benefit included in all roof coatings; however, inferior coatings often cannot perform to that level, causing delamination and adhesion issues when the coating is submerged in water. Ponded water can occur on any roof due to poor design or when drains are clogged and are not able to function properly. This is rather common, especially when semi-annual roof maintenance inspections are postponed or skipped completely. Many roofs experience slopes that do not lead to a drain; this causes rainwater to constantly pool together in a specific location each time it rains, only being alleviated once the water begins to evaporate and dry up over time. 

If you currently have a roof coating installed on your roof, you can determine if the coating has ponded water protection by evaluating an area that has be submerged under water for 1 or 2 days. Press on the area with your thumb and see if the coating is still adhered to the substrate below. If proper adhesion is not occurring, you need to address the issue and solve it immediately. You will need to select a roof coating that can provide proper ponded water protection and you may want to look into an AcryShield SPF Roofing System that allows you to create a new custom slope on the roof that will lead to a drain using spray polyurethane foam – click here for more information.

If you are in search of a new roof coating system for your building and want to determine if the coating has resistance to ponded water, it is best to evaluate the products technical data sheet, test on your roof for actual performance and get referrals for products that claim to provide this protection.

National Coatings has a full line of AcryShield roof coatings that provide excellent waterproofing, superior adhesion, and resistance to ponded water for almost any roofing substrate including: Asphalt, BUR, Mod Bit, TPO, PVC, EPDM, Hypalon^®, Metal, SPF and Concrete roofing.

For more information on our base coats or roofing systems with ponded water resistance, download our FREE Product Brochure!