Though metal roof coating is extremely common these days, many homeowners have several questions about painting their metal roofs. The process of metal roof painting can be broken down to three simple steps. The first step involves determination of the substrate you are planning to paint. This may include the roof metal as well as any existing paint. The next step is determination of the best available products and methods for preparation of the existing surface. In the third step, you need to choose an appropriate coating system for the job.
This brief guide will help you protect your roof and avoid expensive metal roof repairs.
Determine the Substrate: Roofing applications make use of different types of metals including steel, copper, stainless steel, aluminum, etc. Out of these metals, copper is most easy to identify because of its color and shine. As far as steel is concerned, the easiest identification process is to make use of a magnet. Galvanized steel or Terne tin tends to get attracted by a magnet. On the other hand, stainless steel is not attracted by magnets. Aluminum has recently emerged as a popular choice because it is light weight, resistant to corrosion, and can quickly dissipate heat. It’s easy to spot Aluminum because it mostly comes with a factory finish.
After determining the type of metal, it is now time to find out if there is any existing coating. Oil-based roof paints are the most traditional products used for roof coating. In the recent years, however, acrylic paints have also emerged as a popular choice. These two coating types can be identified by rubbing a spot with a rag soaked with denatured alcohol. Acrylic products will melt in presence of alcohol, but oil paints will remain unaffected. Elastomeric and asphalt coatings are used occasionally, and can be identified by their distinctive appearances.
Surface Preparation: As far as coating is concerned, the most appropriate surface is a bare metal. However, it is important to deal with unfavorable surface conditions such as rust and corrosion. Unfortunately, it is difficult to find a bare roof without any previous coating on its surface. Mechanical methods such a sanding, scarping, wire-brushing, etc. can be used to remove existing oil coatings and acrylic products. However, roofs with asphalt products are extremely difficult to prepare for a fresh quote.
Choosing the Coating System: Finally, it is time for you to choose a metal roof coating system, based on the available surface and your intended application.
You should use an oil-based system when you have a rusty surface made of a ferrous metal or there is a previously existing oiled product coating. Acrylic paints can be used on any surface that doesn’t respond well to oil products, such as Terne and galvanized products, aluminum, etc. These paints can also be used for painting over an existing old asphalt coating. Specialized products such as elastomerics can be used to benefit from the heat reflecting properties of these materials.