Polystyrene Insulation R Value Per Inch

For instance if the specified insulation has an r factor of 3 8 and you are using 3 5 inches of insulation the r value is 13 3.

Polystyrene insulation r value per inch.

Expanded polystyrene insulation is similar to the foam used for packing peanuts and it s typically used for insulated concrete forms also knows as icf s. R value then is the r factor of an insulation material multiplied by the amount of material used. Expanded polystyrene eps eps is the insulation used most widely in insulated concrete forms and structural insulated panels sips. The r value for foamular xps insulation is provided from testing at two mean temperatures 40ºf and 75ºf and from two aging conditioning techniques 180 day real.

It also is the least expensive. Eps is suitable for ground contact and can be treated to resist. The connor study test results indicate a rapid drop in r value per inch for eps in the first five years in service with in service r values per inch ranging from 3 13 to 3 70. For a 1 in thick 4 8 panel comes unfaced or with a number of different plastic facings.

The conclusions of r value performance are quoted below and shown in figure 1. The thermal conductivity k of a material is expressed as the rate of heat flow in british thermal units per hour. Each type comes with unique advantages. Products with a higher r value have a higher cost but have an increased capacity to resist heat flow and therefore provide greater insulation.

Expanded polystyrene foam eps is the cheapest and least used foam board product on the market. Also called styrofoam insulation this is the least expensive material. Eps has the lowest average r value of the three most common types of rigid foam insulation around r 4 per inch. Expanded polystyrene made from expanded foam beads that are molded into shape expanded polystyrene or eps is ideal for above grade applications such as exterior walls and offers an r value of 3 6 to 4 2 per inch.

Falls in the middle of the three types of rigid foam insulation in both cost and r value used most in walls or below grade applications recyclable and at about r 5 per inch costs around 42 per sq. The time of testing. Material costs are about 0 31 per square foot for each inch of thickness plus installation costs. It provides r values that range from 3 6 to 4 2 per inch.