Roof Coatings

What is a white roof coating?
A white coating consists of a polymeric binder blended with pigments and other additives to provide two main benefits: 1) protection of roof membranes, for longer roof life cycles; and 2) reflectivity of solar radiation, for lower air conditioning costs.

Why choose a white roof coating?
White roof coatings are applied on a variety of roof substrates or membranes for a variety of reasons. For example, white roof coatings provide protection against water, chemicals, or physical damage. Additionally, white roof coatings protect a roof against excessive temperatures and UV radiation by reflecting visible light and stopping ultraviolet radiation.

What are the benefits of white roof coatings?
White roof coatings provide three key attributes as part of a roofing system:

1.The ability to help shed water and keep interiors dry

2.The ability to help reduce cooling costs for buildings with A/C units, and to help reduce interior temperatures on buildings with no cooling units.

3.The ability to protect and prolong the roof system life cycle by reducing the “thermal shock” stress associated with large temperature changes.

What types of roofing membranes can be coated with white roof coatings?
White coatings can be applied to practically any roofing surfaces, membranes, or substrates. They are commonly applied to sprayed polyurethane roofs to provide waterproofing. They can also be applied to metal roofs, single-ply rubber roofs and modified bitumen roofs. They can even be applied to certain kinds of asphalt roofs. It is important to establish compatibility between the white coating and the underlying roof membrane.

When are primers or base coats necessary?
Correct surface preparation is vital on roofing substrates to readily accept and enhance the adhesion of white reflective roof coatings. It is best to consult the manufacturer for details on roof primers used in conjunction with applications to specific substrates. Primers are typically used to enhance adhesion, prevent bleed through of substrate contaminants and to inhibit or convert rusted surfaces.

What properties should be considered when selecting a white roof coating?
The key criteria for selecting a white roof coating for a specific installation are:

1.Compatibility with the roof substrate

2.Conformance with local regulations and building codes

3.Qualification for available state, local, or federal rebate

4.Requirement for professional application

5.Reflectivity and emissivity values for the product

How are white roof coatings applied?
Application of white roof coatings is typically accomplished with the use of a roller, brush or with conventional airless spray equipment. The user should consult with either the coating manufacturer or airless spray manufacturer for guidance on proper equipment and tip sizes.

Should you consider a coating on a NEW roof?
All compatible new roofs have the option of applying a white roof coating in order to reduce heat loads to roof surfaces that are not reflective as well protecting the newly applied roof which will extend its service life. Some roof membrane manufacturers extend the roof membrane warranty when a reflective roof coating is applied over the newly installed product.

Source:
Solar Reflective Coatings Council