Spray Foam Insulation R Value Per Inch Chart

Open cell spray foam has an r value of about r 3 7 per inch while closed cell spray foam has an r value that may be as high as r 6 5 per inch.

Spray foam insulation r value per inch chart.

Use the following chart to estimate an ideal r value for your insulation project. Its r value is roughly 6 5 per inch. As a benchmark one inch of solid wood has an r value of 1. 4 5 21.

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. Corrosion problems when in contact with steel roofing moisture. Closed cell spray foam aka two pound foam is denser than open cell at about 2 pounds per cubic foot. The primary reason closed cell doesn t need a vapor retarder is because it already has one due to its density and mixture.

If you want to install spray foam in a stud wall and price is no object then it would seem to make sense to specify closed cell spray foam right. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. Open cell spray foam has an r value of about r 3 7 per inch while closed cell spray foam has an r value that may be as high as r 6 5 per inch. 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.

R 0 77 30 phenolic foam insulation r values. Note from this chart that the ideal r value differs for each part of your home. 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. Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system.

All these have r values ranging from r 3 2 to r 3 8 per inch. The r value of closed cell foam is r 6 5 7 per inch. 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. What really matters is the r value of the whole wall not just that of the insulation.

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. If you want to install spray foam in a stud wall and price is no object then it would seem to make sense to specify closed cell spray foam right. 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. A typical 2 4 stud filled with open cell spray foam will have an r value between 10 5 and 14.

In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and an inch of blown cellulose in an attic has an r value of 3 2 3 7. 4 8 7 21. Phenolic foam spray insulation. Very good air bypass leak sealing properties.

8 3 4 4 8 2 20.