Foam Board Insulation R Value Chart

Closed cell spray foam insulation.

Foam board insulation r value chart.

As a benchmark one inch of solid wood has an r value of 1. In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and. 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. R value is a measurement of thermal resistance and measures the ability of heat to transfer from one side of an object to another.

Closed cell spray foam has a far better r value per inch than other less effective insulations like cellulose fiberglass or even open cell foam. These r values are a sum meaning this should be the total r value once you add up the entire depth of 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. 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.

The common denominator among varieties of insulation is the r value. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. This is the product that i typically use to insulate basement walls. This insulation board is probably one of the most widely used foam board insulation products in the residential construction industry.

It has a lower r value per inch than closed cell foam and is vapor permeable. Xps has an r value of 4 5 to 5 0 per inch of thickness. 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.