Foam Board Insulation R Value Chart

For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3.

Foam board insulation r value chart.

Our r value guide to rigid insulation includes the doe s recommended insulation by zone chart r value calculator and base building material r values chart. Closed cell spray foam insulation. Additional r value for a masonry wall constructed using these materials needs to add the insulating value of additional wall components typically included such as 1 solid foam polyisocyanurate r 8 extruded polystyrene r 5 expanded polystyrene r 4 or 1 of perlite r 2 7 and for an exterior air film winter no wind r 0 17 an interior air film again no air movement r 0 68 3 4 of reflective air space no convective air movement r 2 89 1 2 drywall r 0 45 interior wall. It has a lower r value per inch than closed cell foam and is vapor permeable.

The common denominator among varieties of insulation is the r value. Let s use the r value of iko s polyiso insulation enerfoil tm as an example. The table compares minimum lttr values based on the poly isocyanurate insulation manufacturers association s qualitymarkcm certification program and nrca s recommended design in service. Xps has an r value of 4 5 to 5 0 per inch of thickness.

As a benchmark one inch of solid wood has an r value of 1. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and.

Most insulation manufacturers will first list their insulation s r value for a one inch sample then they ll give you a chart demonstrating the other r values you can achieve if you install a thicker version of their product. This insulation board is probably one of the most widely used foam board insulation products in the residential construction industry. Interim update nrca has revised its design in service r value rec ommendation to 5 0 per inch thickness in all climate conditions.