National Coatings Blog

Asphaltic and modified bitumen roofing membranes comprise one of the largest segments of the low slope roofing market. The asphalt used for roofing is usually blended with reinforcing agents such as calcium carbonate to increase strength and decrease flow. If the material is modified bitumen, the asphalt is blended with a polymeric modifier such as atactic polypropylene (APP) to create APP-modified bitumen or styrene-butadiene-styrene (SBS) block copolymers to create SBS-modified bitumen. Two variants are SEBS (styrene-ethylene-butadiene-styrene) and SIBS (styrene-isobutylene-styrene) block copolymers. 

Asphalt is a by-product of the crude oil refining process. After the "lighter fractions" are distilled off, (gasoline, kerosene, diesel fuel, grease) the remaining crude oil, called flux, is the basic building block for asphalt and modified bitumen. While asphalt has excellent waterproofing properties, it is extremely susceptible to attack by UV radiation. The deterioration that is observed as cracking and chalking is a direct result of this attack.  The underlying mechanism is twofold. Chemical analyses of asphalt have shown it to be composed of hundreds of different chemical components. Some of these components are liquids at room temperature, but when dispersed in the asphalt matrix, appear to be solids. Over time and with the addition of heat (IR), these light fractions leach out. This has two effects. First, the loss of this material slightly reduces the size of the roofing material (i.e. volume reduction). This loss of dimension, or shrinkage, may cause stress on the seams and fasteners, reducing the service life of the roof. Moreover, these light fractions also act as plasticizers, making the membrane more flexible, especially at low service temperatures. Some of the stone granules that protect the bitumen cap sheet may become dislodged and collect in the gutters and low spots on the roof. This is a result of the loss of these asphalt fractions that act as "glue" to adhere the granules to the asphalt surface. As the granules become dislodged, more asphalt is exposed to the harmful effects of the sun's UV and IR radiation. This, in turn contributes to a more rapid degradation of the asphalt membrane.

An additional weathering related reaction is that of oxygen in the air with some of the components of the asphalt. This chemical reaction causes the asphalt to become less hydrophobic, as hydroxyl radicals are created on the component chains. This reaction can be observed by wetting aged asphalt with water and checking for a soapy feel. The soapy "feel" is the result of the asphalt reacting with oxygen. 

Understanding the fundamental mechanism for asphalt deterioration now enables us to identify methods for extending its service life. If the asphalt can be protected from the harmful effects of UV, keep it cooler, and prevent its contact with oxygen, it will last longer. This can easily be accomplished through the use of white, UV blocking roof coatings, such as those of the AcryShield product line.

National Coatings AcryPly Roof Restoration System and AcryShield Roof Maintenance Systems are ideal for renewing and restoring your existing Asphalt, BUR, or Mod Bit roofing membranes.  These systems allow you to gain a brand new, leak-free, monolithic roofing system without the extra cost, time and stress of a traditional roof replacement/roof tear-off system. Restoring your aged asphalt roof saves you time, money and allows for a cleaner environment. These systems are ideal for businesses that cannot afford to be closed during construction and application. For more information on our non-intrusive roofing systems, download our FREE Benefits Brochure or contact us at 800-423-9557.

There are several brands of roof coatings on the market and many of these brands have multiple asphalt roof coatings to choose from - How do you know which one to pick? There are several factors to consider: How long has the coating manufacturer’s product successfully been on the market? Can they provide you with credentials and ratings for their products from established roofing organizations? Compare the ingredients listed in the coating you are choosing against other roof coatings.

Let’s dive in and take the first factor into consideration – How long has the coating manufacturer’s product successfully been on the market? Track record is very important. Poor performing products do not last long in any industry; therefore, it’s good to find out how many years the product has successfully worked for others. The AcryShield A400 is an excellent example of an asphalt roof coating that has proven itself over and over again, to hundreds of clients.  AcryShield A400 a top coat with unique asphalt bleed blocking properties, making it particularly suited for a top coat over asphalt, was first introduced to the roofing industry in 1985. This product has been successfully applied over hundreds of millions of square feet of low slope roofs for the past 28 years. It is beneficial to hear from clients who have had first hand experience with the roofing product to know they were satisfied. That is why we provide our customers with a wide range of case histories. If you would like to check out asphalt roof membrane specific case histories, click on these clients - Apple, Google, Kaiser and Harbor Freight Tools.

Credentials and ratings are extremely important when comparing products because they deliver unbiased information while using identical tests to provide accurate results. There are several organizations in the roofing industry that set rigorous standards such as ASTM, AIA, FM, ICC-ES, UL, Energy Star, CRRC, Miami-Dade County, and LEED. The AcryShield product line has numerous products that meet all of these standards (see our credential and ratings page for complete product information). AcryShield A500 first introduced to the market in 1981 – over 32 years ago - meets all of these standards and is an excellent high performance asphalt roof coating that provides longevity and brightness with superior dirt pick-up resistance and protection against biological attack such as algae and mold. A500 was developed specifically for areas where extra levels of low temperature flexibility is required. This product also offers exceptional tensile strength, elongation, and wet adhesion.

Lastly, we want to discuss the importance of the amounts of ingredients used in the asphalt roof coating. We have conducted several tests in our laboratory that compare our products versus our competitions. National Coatings offers premium roof coating products with high levels of ingredients to provide our customers with only the finest and best roof coating products available. We never eliminate or cut down on adding ingredients to our products in order to cut costs. After over 500 hours of exposure in the QUV accelerated weathering apparatus, we found that several of our competitors do just that – they cut costs and performance by eliminating or not adding nearly as much UV blocking pigments into their coatings. They substitute these pigments with cheap “filler” pigments resulting in a shorter life span of the product. UV blocking pigments are the protection the coating provides to the underlying roofing membrane. Without having excellent UV protection, your roof fails sooner, leaking faster and resulting in the need to repair, recoat or replace your roof much earlier than if you had chosen a durable, highly reflective coating with proper amounts of UV blocking pigments.  For more information regarding our test, download our article “There is NO “Or Equal”! Guide.

As you can see, it is important to know the ingredient content of the product you choose as it can adversely affect your roof. It is also great to do a little research and make sure the product has passed standards and tests set by the roofing industry. Lastly, remember the longer the history of success, the greater likelihood you will be satisfied with your choice.