The repainting of a metal roof can be costly and frustrating if the correct paint is not used. This is compounded by the fact that quality metal roof paints are not typically readily available at local building materials suppliers.
The following four tips are essential when choosing a paint for the repainting of a metal roof:
Tip # 1: Know What You Are Painting : Most building materials experience varying degrees of thermal expansion and contraction. This means that changes in air or surface temperature can result in changes to the physical dimensions of a building material. Metal panel is specially given to this phenomena. For example, if you stand near a home with a metal roof on a cold winter day, you can hear the panel pinging as it expands with exposure to the sun. This pinging noise is caused by the panel stretching along its width and length as the surface temperature rises (with exposure to the sun). When the sun goes behind a cloud, you will hear the same pinging noise which is now attributed to the panel shrinking as its surface temperature decreases. In summary, metal roof panels increase and decrease in length / width numerous times through the day / evening.
Tip # 2: Paint Properties: Knowing that the metal roof expands and contracts, it is important to choose a paint with an appropriate degree of elasticity. Why do traditional household paints crack & peel so quickly after being applied to a metal roof? Answer: As the panel stretches, these paintings are not enough enough, become brittle and crack. Once they have formed cracks in their surface the peeling process is always close behind. Unless a paint is specifically designed for use on a metal roof and is indicated as such on the label, do not take a chance. This applies to both primer and top-coats. Selecting the correct paint while using an ill-fitted primer will result in a peeling roof.
Tip # 3: Choosing The Right Product : Choose a water-based acrylic, elastomeric metal roof paint. This will provide you with a product that is A (specifically designed for use on metal panel, and B ) is easy to clean-up in the event of a mishap. Important Note: I often hear / read concerns to the effect that water-based paint is not as long-lasting as solvent-based. In my experience and in the experience of other industry veterans, this is simply not the case anymore. Water-based acrylics are less brittle than solvent-based paints, more environmentally friendly and easier to clean-up.
Tip # 4: Paint Longevity : When applied in accordance with the manufacturer's application instructions, a quality metal roof paint should last 8 – 12 years. No manufacturer will provide a guarantee as to lifespan as the performance of the product is dependent upon the application process, however following basic industry guidelines before, during and after the painting process will typically ensure repeating results.