Could Your Roof Use a Coating?

05/30/2017 | By Janelle Penny

Why your roof might benefit from extra layers

Roof Coatings

Roof Coatings can help increase your roof's reflectivity, reduce peak energy demand and prolong the roof's life.

Coating systems are more than just a light-colored layer over your roof – they can reflect sunlight, protect the underlying roof system from the elements and even lower your energy demand.

Choosing a cold-applied product in particular can also allow for savings on labor since the contractor doesn’t need to deal with bitumen feeding equipment or other tools for hot-applied systems, explains Mark Graham, Vice President of Technical Services for the National Roofing Contractors Association (NRCA). Many cold-applied coatings can be applied straight out of the container with a roller, brush or sprayer.

Could a cold-applied roof coating be a good fit for your building?

When Coatings Make Sense

Coatings can be applied to nearly every type of roof, save for those covered in gravel or other ballast, notes Dr. James Hoff, President of TEGNOS Research. Building owners usually opt for roof coatings based on one of three main reasons.

Restoring an aging roof: “If a roof has been exposed for 10 to 15 years and a coating can extend the life by 10 or 15 more years, customers will consider applying a coating system rather than putting a whole new roof on,” explains Joe Mellott, Vice President of Imetco and Former President of the Roof Coatings Manufacturers Association (RCMA). “It’s a very sustainable way of managing your roof environment.”

Protecting a new roof: Applying coatings earlier in the roof system’s life – even as early as the completion of the brand-new roof – is becoming increasingly popular, Mellott adds. The coating protects the new roof from damage from the start and adds reflectivity that the roof system underneath may not have.

Changing the color: This typically takes the form of a light-colored coating on a dark roof, says Graham. Coatings with high reflectivity don’t allow the roof to get as hot as non-reflective colors do, which can take the edge off of air conditioning costs and make the building more comfortable. The actual energy savings from cool roofs are under debate, but older roofs that are dark-colored and poorly insulated stand to benefit the most from a reflective coating, explains Hoff.

“One other factor can significantly change with a cool roof coating, and that’s if the building owner is paying for electricity with a combination of standard net charges and peak demand charges,” Hoff says. “A lot of utilities have additional charges based on the peak level of electricity that you use. In many buildings, the peak level will occur in the mid- to late afternoon and it will be related to cooling costs. You have an opportunity for more savings if you’re paying for peak demand charges and you lower demand.”

Is Your Roof a Coating Candidate?

Determine whether a coating is a good fit for your roof by first examining the condition, Graham recommends: “The roof has to be in relatively good shape or be repairable prior to the coating installation. One trap that building owners get caught in is that they try to put a coating on the building when the roof is too far gone. The key is to coat the roof as a preventive measure rather than ‘I’m having a roofing problem and need to do restoration work.’”

Look for areas where ponding water collects as ponding conditions are tough on coatings, Hoff suggests. You’ll also need to clean the roof before the coating is applied, so make sure that whatever is on the roof is removable. Understanding typical accumulation on your roof will also help you determine what kind of coating your roof needs.

“Examine the environment of the roof. If there’s going to be a lot of ponding water, you may decide to go with a certain type of coating. If it’s going to be exposed to chemicals, debris or emissions from outside or around the building, you may consider different durable solutions,” explains Mellott. “You can also look at the dynamics – whether you’re worried about thermal expansion and contraction and whether you need flexibility. There’s a lot beyond reflectivity that helps buyers measure coatings.”

Roofing professionals will help you match the substrate you have to a compatible coating, as well as determine whether your roof needs any repairs before applying the coating, Mellott adds.

Get Your Roof Ready

Your roof has to be clean and dry before any coating system is applied. Follow the manufacturer’s instructions for your coating to determine how best to prepare the roof surface. “You can’t paint dirt,” Mellott adds. “Some people clean it and don’t dry it, and they end up with pimples in the coating.”

Most coating systems involve a two-coat process that starts with a primer, Hoff notes, so apply the recommended primer for your roof type. This ensures that the top coating adheres to the substrate correctly. The manufacturer may also specify certain flashing and detailing techniques to finish the installation. Make sure the installers are following the directions to the letter to ensure that your warranty remains intact.

“It’s more sophisticated than painting a wall,” Mellott says. “Make sure you’ve got properly trained installers.”

Janelle Penny janelle.penny@buildings.com is Senior Editor of BUILDINGS.


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