R Value Of 3 Spray Foam Insulation

When stud bays are partially filled with closed cell spray foam the exposed portion of the studs reduces their r value in comparison to a wall that is totally filled with open cell spray foam.

R value of 3 spray foam insulation.

For example if a 2 4 wall has 3 in. Closed cell spray foam insulation. R matte plus 3 thermasheath 3 is rigid foam plastic thermal insulation r matte plus 3 thermasheath 3 is rigid foam plastic thermal insulation board. When stud bays are partially filled with closed cell spray foam the exposed portion of the studs reduces their r value in comparison to a wall that is totally filled with open cell spray foam.

As a benchmark one inch of solid wood has an r value of 1. For example closed cell spray foam depending on brand can offer an r 6 or r 7 per inch. 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. 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.

Open cell foam insulation values r3 r4. 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 your attic to reach r 30 if you live in zones 2 or 3. It s made of environmentally sound closed cell polyisocyanurate foam bonded to a durable white matte non glare aluminum facer and a reflective reinforced aluminum facer. For example if a 2 4 wall has 3 in.

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 foams are between 5 and 1 lbs per cubic foot and have an r value of 3 0 4 0 per inch of insulation. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. Of closed cell foam insulation the r value of the studs is based on a stud depth of 3 in not 3 1 2 in.

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. I m not going to dive into the energy code here but these numbers apply to many climate zones the latter being allowed under the ua tradeoffs rule. Closed cell spray foam r values. 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.

For 6 inches r 15 or r 19 etc. All these have r values ranging from r 3 2 to r 3 8 per inch. Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system. Since closed cell foam has a higher r value per inch installers generally spray 2 in walls and 3 in rooflines to meet the energy code requirements of r 13 and r 19 respectively.