Roof Coating Applications
When comparing types of roof coating products, the type of roof you plan to coat must be known. The roof's condition is also a must know factor, and if this is its first coating. Roof coatings are different from roof coverings in that they repair or prevent damage to existing roofs with sealants and barriers that aid in insulation and protect against leakage and sun damage.
- Metal roofing usually comes factory coated, but you can coat it again after installation for added protection. Know the coating used on your metal roofing, if any, because silicone and acrylic products don't adhere well to each other. Most metal roof coatings are acrylic, aluminum, rubberized aluminum, white, polyurethane or polymer-based. When comparing these products, you should consider the roof's current condition, code requirements, budget and desired performance. Product performance may be waterproof or reflective, for example. You might also consider using a zinc-rich metal roof primer to increase adhesion and inhibit rust.
White Reflective Coating
- Many reflective roof coating products are Energy Star rated and approved for the program. Reflective coatings reduce energy used to cool buildings by 10 to 15 percent. A roof's surface temperature can be lowered by 100 degrees Fahrenheit when coated with an Energy Star approved reflective coating product. White, reflective roof coating products can be applied to nearly any existing roof material, including shingles and asphalt. Products with a high solar reflectance are sometimes called albedo. White roof coatings get dirty and weather more quickly than other roof coatings. For these reasons, it's generally preferred for flat roofs.
- Rubber roof coating products are a common choice for roof repair. Rubber products are waterproof, have high adhesive strength, hold up to extreme weather conditions and apply easily with a roller. This type of product can be used on tar, metal, concrete and other roofing materials. Rubber coatings also come in white for a reflective quality.
Differences in Roof Coatings
- Caulk can be used on most roof toppings that have cracks and holes in them. Caulk is made from various substances, and silicone and polyurethane are among the most commonly used. Caulk is cheap, easy to use and can be repeatedly replaced when it cracks from age or wear. Flexible caulk is a bit pricier but holds up better to extreme weather changes that cause it to expand and shrink.
- Roof repair primers help repair and coating materials adhere to the roof’s surface. Different formulas are available for flashings, valleys, vents and related roof accessories. Prior to the application of other roof coatings, primers are applied to roofs made of wood, concrete, masonry materials, plastic vinyl and metal. To properly seal the surfaces, primers have to be thoroughly dried before the application of sealants and coatings. Primers cannot be used on asphalt roofs.
Elastomeric Roof Coating
- This thick coating is flexible like caulk, but used to coat large expanses of roofing with a thick, paint-like material. The coating, which can be applied over almost any roof surface, seals leaks and is a good preventative coating to prevent leaks and extend the life of the roof. Elastomeric roof coatings are white and reflect light up to 98 percent, which can lower the temperature of the roof up to 12 degrees Fahrenheit, which saves on building cooling costs.
- The seams of roof coverings deteriorate over time, and application of seam coatings seals the gaps and prevents extensive damage from moisture and sun. The areas most prone to seam separation are the flashings around skylights, vents and pipes, crash buttons and J-rails, but it’s prudent to check any areas of the roof that show wear or rust stains and apply seam coatings as needed.
Single-Ply and EPDM
- Some of the oldest and most reliable roof coatings are elastomeric solutions made from ethylene, propylene and diene monomer. This chemical combination protects against sun, moisture and abrasion, and resists shrinkage in extremely cold climates. It comes in a variety of thicknesses and is available with or without polyester fabric reinforcements, which increase its durability.