White Cool Roof Topcoat vs. Aluminum Roof Coatings?

After what you read below, you will become aware that the need to redo aluminum coatings on flat and low slope roofs every few years represents liability and inefficiency versus premium, white cool roof coatings. The complete answers to the aluminized coatings question versus a higher quality, elastomeric low-slope coatings  like that are ENERGY STAR rated are as follows:

1. Aluminum coatings are nowhere near as efficient in reflecting the sun’s radiation, not initially nor after 3-4 years in temperate environments, which is their useful life before they must be re-coated.
 
2. The range of performance on various aluminum coatings from the major manufacturers on the CRRC makes it clear.  All aluminum coatings start out over 20% less efficient in Solar Reflectance (SR) and Thermal Emissivity (TE) and end up on average almost 50% or more less efficient in just 3 years compared to ECO-THERM Elastomeric color white uncleaned, for instance.  Aluminum coated roofs are much hotter than the majority of cool white top-coated roofs (at proper number of coats) even more so because of their poor Thermal Emissivity properties. This means that the aluminum coatings retain heat in the substrate roof much longer. ECO-THERM and some other white coatings actually increase in thermal emissivity in its first three years after installation due to particle compaction. 

3.  Aluminum coatings do not stand up to being cleaned without losing their particles and baring the asphalt, rubber or tar roof underneath. ECO-THERM for example does not attract dirt and is cleanable. Most cool white coatings, however, when washed will not return to their initial solar reflective efficiency due to dirt which embeds in them.

4.  Aluminum coatings are early 20th century technology and are toxic for the environment. They slough off gradually and send their aluminum particles everywhere (wind, rain, snow melt and sun do that job well).

5. Various Federal and university lab tests have  confirmed that cool elastomeric topcoats protect the roof underneath them because 1) they keep them cooler (less wear from thermal shock), 2) they physically prevent water from penetrating the roof layer.
 
Aluminum suspended in a toxic carrier at a few microns of thickness that washs and blows away are not in the same ballpark. Compared to a high quality elastomeric, white cool coating like ECO-THERM, this is not an apples to apples comparison.
 
6. Perhaps only one aluminum coating meets initial LEED credit requirements, but all aluminum coating types and many cool white coatings fall off precipitously as noted by their performance efficiency ratings (initial and 3 year), so if any builder, property owner or corporation is serious about the cool roof issue and ROI (return on investment) for their “cool” low slope or flat roofs, then there is little to be said for aluminized roof coatings except their initial cheapness and initial cheaper labor to install. 
 
Which “cool roof coating” do you now think is a better use of your money and care for your properties?
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