Application specifics
Roof coatings can be applied using spray, roller, or brush to all types of roof membranes and substrates. Coatings can be applied by a properly trained building owner or an experienced roof coating applicator. However, a roofing contractor is strongly recommended if there are any issues, such as existing leaks, wet insulation, damaged deck, or manufacturers’ warranties.
All roofs should be designed and built to have positive drainage and not allow ponding water. While some coatings are designed to withstand ponding conditions, this is not the case with others. One must check water swelling and absorption properties to see whether a coating can withstand ponding water conditions for extended periods.
As a coating naturally wears away, additional coating can be applied. Most coatings systems are re-coatable and provide a sustainable roofing system when properly maintained. The manufacturer should be consulted for specific requirements on re-coating applications.
Curing and drying time
For water-borne coatings, the ambient air temperature should be 10 C (50 F) and higher, with no rain for the next 24 hours. Solvent-borne coatings can be applied in colder weather, but as always, the coating manufacturer should be consulted.
While modern technology permits the application of some roof coatings at low temperatures, one can expect the cure time to be longer than on a warm summer day. A product that may cure overnight at a temperature of 21 to 23 C (70 to75 F) may take several days to cure at 4 C (40 F).
VOC issues
There is an environmentally based effort to continue to reduce the volatile organic compounds (VOCs) in roof coatings. Found in a wide variety of products and in naturally occurring processes, VOCs are compounds of carbon that participate in atmospheric photochemical reactions. Ground-level ozone is one of six ‘criteria’ pollutants regulated by the U.S. Environmental Protection Agency (EPA), because it has negative impacts on human health and can be damaging to vegetative growth. Ozone is formed when VOCs and nitrogen oxides (NOx) combine with sunlight. However, VOCs help protect roof coatings during shipment by providing freeze-thaw resistance. On the jobsite, VOCs help condition or soften the substrate and improve adhesion of the roof coating. They are integral to specific raw materials used in the roof coatings products. Roof coating manufacturers recognize the need to reduce total VOCs—over the last few decades, 90 percent of VOC content has been eliminated from roof coatings.
The most common replacement for VOCs is water, but water-based roof coatings have unintended consequences, including;
- hard settling, or phase separation, of the components during transportation and storage of the product before application;
- poor adhesion of the product to the roof substrate;
- the need for more coats of the product and heavier coverage rates, therefore possibly increasing total
VOC emittance; - reduction of product lifespan, requiring more frequent applications; and
- elimination of roof coating product lines that cannot be reformulated.
Conclusion
Roof coatings can provide many benefits, from aesthetics, to energy, longevity, and performance.1 There are a wide variety of choices for roof coatings, many considerations when selecting and specifying roof coatings, and many reasons why coatings are used on new and existing roof systems. It is important to understand why a roofing coating is used so it can be selected properly.
James R. Kirby, AIA, is the codes and standards director for the Roof Coatings Manufacturers Association (RCMA). Kirby has more than two decades of roofing industry and association experience, and has a well-rounded knowledge of roofing materials and systems as well as standards development. He can be reached at jkirby@kellencompany.com.
I’m surprised that I have never heard of roof coatings, especially since they have been around for 50 years! The shingles have been falling off of my roof lately, so I need to get it fixed soon. If I coat the roof after replacing the shingles, will it last longer?
This was a lot of help! I wasn’t sure which coating I should go with for my new roof so this is great. Thanks so much for sharing.
Some great info about the different roof coatings!
It is interesting to see how many different type roof coatings there is. We have been using acrylic roof coatings for years, may have to look other options now!
I want to get something that will make my roof last longer. It makes sense that I would want to have it coated! It seems like a good way to keep it safe from the elements.
Informative post shared about the different roof coatings. I was doing a little survey on types of roofs done these days. Thanks so much for sharing.
Roof coatings is an effective way to restore flat, low sloped, EPDM and metal roofs – but almost every roof can benefit from reflective roof coating, whether acrylic or rubber.
Thanks for sharing! It’s awesome how you mentioned about such an option which protects and extends the service life of the roof. My wife wants to prepare our roof for the autumn with its rains, and as I’m not a handyman we need professional roofing services. So’ll definitely consider these recommendations in order to protect our house to the greatest degree.
I had no idea there were so many options for roof coating. Ive been racking my brain trying to figure out what Im going to do. I live in tucson where roof coating is super important as the sun and monsoons are especially brutal. This article: http://bluecoyotepainting.com/tucson-roof-coating-what-to-know/ says I should be doing it every 5 years or so. Im hoping the right coating can last longer than that.
It did catch my attention when you talked about how asphalt coatings are a perfect choice for roof coating if you want your roof to be protected from the cold and inclement weather. My father is interested in roof coatings to extend the life of our roof. We know how extreme weather conditions can affect the lifespan of our roof, so it’s important for us to choose a roof coating that can protect our roof from harsh weather conditions.
On old, weathered asphalt roofs, many coating manufacturers recommend use of an asphalt primer after cleaning the membrane to prepare the surface for coating. Primers for metal roofs A number of different types of factory-finished, metal roof panels are available. EPDM Roof Coatings is good for roof strength in long term.
Finding a good contractor can be difficult because there are so many different ones out there. I really like the idea of asking your family and friends about who is good to to hire.