SPF requires protection from the sun’s ultraviolet radiation, moisture, and foot traffic. This coating helps to protect and seal the foam from any damage from these or other elements.
Once the SPF has been applied to the proper thickness and finish specifications, a protective layer of elastomeric coating or gravel is applied. This protective layer produces a durable, weather-resistant surface that can be walked on for regular maintenance.
The most common cool roof coatings used over sprayed polyurethane foam (SPF) and other roof deck surfaces are light/white colored. The most common types are:
- Acrylic
- Silicone
- Urethanes
- Polyurea
Some suppliers and contractors use a thin layer of gravel spread over the foam. This system has been used very successfully. However, elastomeric coatings are more common. The coatings are spray applied as a single component or plural component system and can be silicone, acrylic, butyl rubber, polyurea, and different urethanes. The various materials all have other physical properties and vary in cost. Check with your supplier for more details.
Coatings are usually installed in two stages: a base coat and a final top coat. Granules are often embedded into the last skin and offer added protection against mechanical ultraviolet damage.
In time, these coatings will require maintenance or replacement, but just like paint on your house, they can be removed and re-applied to keep your SPF roof system in peak performance for decades.
An SPF roof, like most other systems, will expand and contract during different climate conditions. It is essential that the protective coating contract with the SPF or ser; severe can result in delamination. This physical characteristic is called elongation and is something your materials suppliers can help you with to properly match the SPF and coating system to the roof system and climate.