Elastomeric and Steel Roofs: How Can Your Roof Last Longer?
Next to stone, metal roofs are one of he most durable materials to last through the ages; they have been traced back as far as the third century, B.C.! Although metal roofing has changed over time, in modern times, steel has become the material of choice for metal roof systems. Steel is more affordable than copper, tin, aluminum, or stainless steel and, with the development of Galvalume coatings and high performance paint finishes such as Kynar and Hylar, steel roof systems can achieve life spans of 50 years or more. However, many of these coatings have only been used in the metal roof industry since the late 1970’s, which means there are millions of square feet of steel roofing with coatings that are at or past their life span. Just take an aerial tour using Google Earth and you can easily identify those older steel roof systems by their oxidized, rusted surfaces.
A whole cottage industry of steel roof restoration companies has come into being with all this square footage of aging metal roofs. The roof repair product of choice for these restoration companies is the elastomeric line of roof coatings. Elastomeric is defined as a liquid applied polymer with elasticity (in other words: a liquid rubber coating). These products are being marketed as the “end-all” in metal roof restoration. Manufacturers of these products claim that they seal leaks, prevent corrosion, add insulation value, have high reflectivity values, and more.
Building owners need to educate themselves on these products before they consider their use. Additionally, owners should be very skeptical of the 10 to 20 year warranties these products and their installers claim to have. At best, these products are a 5 year Band-Aid and they may limit a building owner’s options down the road when that Band-Aid starts to fail.
The most common complaint with these products is that the roof still leaks or leaks reappear a few months after the product has been applied. At the extreme end of using these products is the potential for complete panel failure. Metal roof panels are designed to expand and contract and it is this movement that brings out the flaw in the elastomeric products. These products are flexible, however, over time they become less flexible. In fact, with wear, expansion and contraction these products tend to delaminate and tear. These openings allow water to migrate between the elastomeric coating and the steel panel. Over time (less time in high acid rain areas), the steel panel corrodes and starts to fail as a water tight covering and even becomes structurally deficient.
As a potential customer of one of these roof restoration companies, you need to be aware of the potential pit falls of using these products. It is important to recognize that these products are a short term fix and not a real roof restoration.
As discussed above, roof coatings are a short term fix at best. However, the consideration of a new metal over metal roof system will be a long lasting upgrade to your roof, lasting up to 50 years or longer. Additionally, building owners need to be proactive with their existing metal roof system. A good roof maintenance program will add many leak-free years to your existing metal roof.