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The Federal Center’s old 630,000sf asphalt roof was coated with Super Therm cool roof coating


What if there were a better way to fix your roof problem than rip it off and replace it? What if you could put a new roof over the old one and have it wear like a new roof, complete with warranty and get some added benefits as well? Two of those benefits would be a sustainable roof system and a reduction of heat transferred into your building.


Why Use a Cool Roof Coating?
Cool roof coatings are an exciting solution to many heat reduction and roofing needs. The coating forms a monolithic membrane without seams and can be a great weather barrier. They can rejuvenate most worn roofs and eliminate tear off of the old roof. They often come with a 10-year warranty and often qualify for a utility company’s rebate program. (Check under the “peak energy reduction” requirements or other programs for your utility to see if you qualify.) Some direct benefits to the end user are

 

  1. Increased personal comfort, especially during hot summer months
  2. Reduced air conditioning use and repair
  3. Energy savings typically of 10 to 30 percent
  4. Decreased roof maintenance costs due to a longer roof life
  5. Reduced maintenance due to reduced thermal shock
  6. Decreasing the size and prolong the life of your air conditioning system
  7. Lowering roof maintenance costs and extend roof life,
  8. Avoiding reroofing costs
  9. Reducing solid waste


What is a Cool Roof Coating?
A cool roof coating reflects the sun’s heat and emits absorbed radiation back into the atmosphere. The roof stays cooler and reduces the amount of heat transferred to the building below, keeping the building a cooler and more consistent temperature. The coating aspect means it goes on similar to paint. Most can be sprayed or rolled on, making application more cost effective than other methods. 


The two basic characteristics that determine the coolness of a roof are solar reflectance (SR) and thermal emittance (TE). Both properties are rated on a scale from 0 to 1, where 1 is the most reflective or emissive. The Cool Roof Rating Council and Energy Star measure these two properties for roofing products, both for the product’s initial values and after three years of weather exposure. These directories are available to the general public at no charge, and it allows you to compare the rated values of various product types and brands.


Will it Work for Me?
Climate zone is one main factor influencing how much will be saved. Some savings will hit near 50 percent in hot climate zones, depending on the coating, level of insulation, building use and several other factors. 

But these products are not just for warm and hot climates. One national study found cool roof coatings are an effective energy reduction measure in all states. As reported by LBNL:


“A cool roof can decrease annual cooling load even in climates with zero nominal (base 18 degrees Celsius) cooling degree days if air conditioning is required to remove the building’s solar heat gain and/or internally generated heat,” according to Ronnen Levinson and Hashem Akbari of Lawrence Berkeley National Laboratory. “Prior research has indicated that net annual energy cost savings are greatest for buildings located in climates with long cooling seasons and short heating seasons.”


Substantial projections exist for cool roof coatings at minimum performance standards. Top performers can raise the savings estimates by 40 percent or more.


These coatings are tough, weather-resistant coatings. Many are also vapor and air semi-permeable and close cousins to commercial elastomeric coatings. They come in single component coatings or multi-step systems depending on your needs. Many are water based elastomerics, others are polyurethane, epoxy, or liquid EPDM. The type of coating needs to be matched with the type of roof you have for a successful installation.

Choosing the Right Coating
When choosing a coating it’s important to look at the 3 year weathering data. Look for the least amount of difference between that and the new readings. The results only go down with time. Some other factors will influence your coating selection:

1.  The type of roof you currently have (coating compatibility)
2.  The wear or condition of that roof
3.  How long you would prefer the coating to last – quick fix or long term solution
4.  Warranty

A quick word about roofing contractors. Roofers know about fixing and replacing roofs. Some know about roof coatings. Even less know about cool roof coatings. Those that do are usually locked into the coatings offer by their suppliers. It might be a good idea to find a roofing consultant and a coatings consultant to work together to get all aspects of the job covered.

A more detailed analysis can be found here: http://coolroofs.org/resources/home-building-owners
I’m a dealer for this coating, but I think my bias is earned: http://betterpainting.net/super-therm-cool-roof-coating.html

To your better looking longer lasting painting results,
Tim Hoeffel
Better Painting & Coatings