The Roofing Resource Blog

Commercial Metal Roof Coatings for Dummies - What You Need to Know

Tue, Feb 17, 2015 @ 08:00 AM | Exterior Pro Roofing

Metal roof coatings are the most cost effective approach of all metal roof repair options. Metal roof coatings allow business owners and facilities managers to extend the life of a commercial metal roof by up to twenty-five years.

With over 1000 varieties of metal roof coatings available, it is difficult to choose the best solution for your situation. This article should clear up the confusion and provide business owners and facility managers all the information they need to make an informed decision about metal roof coatings.

Metal Roof Coatings Purpose and Application

rusted_metal_roofAfter 20-40 years, metal roofs corrode and rust. In addition to extending the life of the underlying roof, the metal roof coatings improve the appearance with a durable and seamless coating. Metal roof coatings are available in many colors including customized colors to match or enhance existing building architecture.   

Roofing contractors apply the coatings as a liquid like paint and the covering measures from paint film thickness (3 dry mils) to up 40 dry mils. The contractors apply a protective coating over metal roofs. Do not use metal roof coatings to cover asphalt roofs because it inhibits normal shingle drying leads to moisture related problems.

The metal roof coatings become the top layer of the roof and protect the underlying metal from further rusting, corrosion and other types of deterioration.

Not to be confused with deck coatings that are traffic bearing, metal roof coatings do not withstand vehicle or excessive pedestrian traffic. The primary purpose of metal roof coatings is to provide water and weatherproofing. Metal roof repair is far more economical than roof replacement.

 Varieties of Metal Roof Coatings

The primary varieties of metal roof coatings are:

  • metal_roof_coatingsAsphalt – this is the traditional method of extending the life of a black roof. Reflective asphalt coatings, often used as a coating for a metal roof, offers additional protection by providing a renewable weather barrier with additional protection at transitions and flashings and reflects the sun’s rays. Asphalt coatings may be solvent or water based.
  • Polymeric (elastomeric) coatings - Polymer modified asphalt coatings, provide improved elongation and recovery properties over conventional asphalt coatings. Elongation and recovery are important because metal panels expand and contract with temperature changes.
  • Pigmented latex coatings are the most common materials used in coating metal panels because they are more resistant to chemicals, oils, and solvents. Like the polymeric coatings, they also provide elongation and recovery.
  • Polyurethane coatings are used when industrial chemicals or oils are present.
  • Solvent borne elastomeric coatings have a good elongation and recovery, and can provide advanced metal adhesion, but are less resistant to solvents and oils than  acrylic or polyurethane coatings. These types of metal roof coatings are not typically used for restaurants where there are significant deposits of oils and solvents.

What Materials Are Most Popular 

The most popular materials are acrylic-aluminum coatings, rubberized aluminum, Styrene-Butadiene-Styrene (SBS) or SEBS Styrene-Ethyl benzene-Butadiene-Styrene membranes, polyurethane, soy-based polymers, and other polymers.

The SBS and SEBS metal roof coatings provide tough, polyester-based resilient modified bitumen membranes. These membranes are available in popular colors to complement existing architecture.

Thanks to new synthetic materials, metal roof repair is easy, affordable, and durable. The metal roof coatings are available in many colors to complement the existing architecture of a building and can be applied much faster and safer than asphalt.