Insulation comes in many forms, including large boards of high-density foam. One type of board is available in both pink and blue colours, leading some to wonder what the difference is between them. They are both expanded polystyrene foam -- stronger than regular white foam -- and cut into boards to make them easier to use for wall and ceiling insulation. The difference between boards of this foam and boards of white foam is the R-value of its insulation protection, but the difference between blue foam and pink foam is only in colour and manufacturer.
Pink and blue insulation boards are both made from expanded extruded polystyrene, or XEPS. This is also called expanded polystyrene, or XPS. Pellets of polystyrene plastic are mixed with chemicals. To make the mixture foam, a different chemical referred to as a blowing agent is injected. The mix is then shaped through a special machine, and when it is finished shaping, it can be cut into boards.
Insulation foam is meant to keep a home warm or cool by protecting the inside from temperature changes outdoors. Its effectiveness at doing this is expressed in the form of an "R-value." R-values indicate how well the foam resists transferring heat. Denser materials have higher R-values. R-values are expressed per inch of the material; the higher the number, the better the insulating ability. XPS boards usually have a rating of R-5 per inch.
Colour and Efficiency
The colour of the foam board has no effect on its efficiency. XPS boards are coloured blue or pink to easily differentiate them visually from cheaper "beadboard," which is white. Beadboard is known by that name because its surface easily reveals the separate beads of polystyrene from which the board was formed. Air or moisture can become caught between these beads. XPS board, because it has no such visible beads, has a more consistent density and R-value than beadboard.
The difference in colours of XPS boards distinguishes their manufacturers. Pink board is made by Owens Corning and marketed under the name Foamular. Blue foam board is made by Dow Plastics and marketed under the name styrofoam. Other than the colours and manufacturers, there is no difference between pink and blue XPS foam board.