Coatings Directly Over Spray-Polyurethane Foam: 

When applying an appropriate coating directly to polyurethane foam, it is recommended to not leave foam uncoated or exposed for periods exceeding 48 hours. Consult with manufacturer or manufacturer’s installation guidelines for specific recommendations. 

Material and system description​

SPF-based roof systems are constructed by mixing and spraying a two-component liquid that forms the base of an adhered roof system. SPF can be installed in various thicknesses to provide slope to drain or meet a specified thermal resistance (R-value). A protective surfacing is then applied to the foam to provide protection from the elements.

The first component of an SPF-based roof system is rigid, closed cell, spray polyurethane foam insulation. The foam is composed of two components: isocyanate and polyol. Transfer pumps are used to get the components to a proportioning unit that properly meters the two at a one to one ratio and heats and pumps them through dual hoses. The components are mixed at the spray gun, which is used to apply them to a substrate.

The second component, the protective surfacing, typically is a spray applied elastomeric coating, though hand and power rollers can be used. The protective surfacing also can be a membrane, such as a fleece backed thermoset single ply membrane. The purpose of the surfacing is to provide weatherproofing, protect the foam from UV exposure, provide protection from mechanical damage and assist with the fire-resistant characteristic of the roof system.

The generic types of coatings used on SPF-based roof systems include:

Butyl Rubber
Aromatic Polyurethane Elastomer
Aliphatic Polyurethane Elastomer
Modified Polyurethane ElastomerMineral granules or sand may be broadcast into a coating to provide increased surface durability and aesthetic value.

The chemicals used to produce polyurethane foam compounds are manufactured or blended to perform in various temperature ranges. Manufacturers of spray polyurethane foam based roof systems offer materials in different reaction profiles. Profile change is created by altering the chemical ingredients, usually with a catalyst, to compensate for ambient temperature changes. Conditions such as wind speed, sunlight, surface moisture, humidity and temperature of the substrate can affect the reaction of the polyurethane foam.


What is Spray Polyurethane Foam Roofing (SPF)?

SPF is a closed-cell roofing material formed by combining two liquid components. when these two materials meet in the mixing gun, thety expand 20 to 30 times their volume immediately. Forming rigid polyurethane foam (PUF). This is sprayed on the entire roof the desired thickness, to form a seamless monolithic surface including flashing, penetrations and parapet walls. this eliminates seams and cold joints, the primary source of major leaks and provides a durable waterproof covering that bonds tightly to nearlyany property surface.

For more than 30 years (SPF) has been used as a roofing and insulation material. SPF systems have been proven through comprehensive independent studies to be dependable, long last, and very affordable. There are foam roofs today that have been in place for more than 30 years, and if properly maintained they should be able to last indefinitely.

SPF has an initial R-value of 7.14 per inch thickness. This provides more thermal resistance with less material than any other type of roofing insulation.