Spray Foam Insulation R Values

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.

Spray foam insulation r values.

When the time comes to assess the type of insulation your home needs r value is a common term you will hear. Spray foam the truth about r values r value does not measure heat movement carried in the air. 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 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.

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. 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. 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. 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.

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. The r value for open cell is typically around 3 7 at 1 thick and varies by manufacture. Rigid foam boards trap air or another gas to resist conductive heat flow. 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 of closed cell foam is r 6 5 7 per inch. 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. 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.