foam

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:

  • Acrylic
  • Butyl Rubber
  • Hypalon™
  • Silicone
  • Aromatic Polyurethane Elastomer
  • Aliphatic Polyurethane Elastomer
  • Modified Polyurethane Elastomer

Mineral 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.