Spray Foam Insulation R Values

Spray foam the truth about r values r value does not measure heat movement carried in the air.

Spray foam insulation r values.

All these have r values ranging from r 3 2 to r 3 8 per inch. Contractors often use it to insulate under slabs ceilings walls and roofs. Insulation r value measures how well a particular insulation resists heat flow. Bulky materials resist conductive and to a lesser degree convective heat flow in a building cavity.

Open cell spray foam insulation is air impermeable and is applied with a minimum of 3 5 on average and can be used for attics interior floors walls and soundproofing. The r value of fiberglass insulation is approximately 2 2 per inch so much thicker fiberglass insulation is required to achieve the same r value of 38. The r value of closed cell foam is r 6 5 7 per inch. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.

It performs much better than any form of batt for stopping air flow but it is not as complete of an air seal as closed cell spray foam. 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. 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. R values are additive so you can multiple the number of inches of insulation thickness times the r value to arrive at a total insulation value.

Open cell spray foam typically has an r value of 3 5 per inch and it should be noted that open cell does not form a tight air seal. Open cell spray foams are between 5 and 1 lbs per cubic foot and have an r value of 3 0 4 0 per inch of insulation. When the time comes to assess the type of insulation your home needs r value is a common term you will hear. The r value of spray foam insulation is approximately 6 per inch so those using spray foam as their insulator will need about 6 3 inches of thickness to reach r 38.