Blown Attic Insulation R Value Per Inch

How much is enough.

Blown attic insulation r value per inch.

As a benchmark one inch of solid wood has an r value of 1. Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. The higher the r value per inch of thickness the better job the insulation will do when you heat or cool your home.

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. You can use the small pressurized cans of foam. Foam in place insulation can be blown into walls on attic surfaces or under floors to insulate and reduce air leakage. By today s standards most homes built more than 10 years ago can be considered under insulated.

Cellulose insulation has a baseline r value of 3 8 per inch. Some installations can yield a higher r value than traditional batt insulation for the same thickness and can fill even the smallest cavities creating an effective air barrier. This calculator is to be used as an estimating tool only. Input depth of existing blown in insulation in inches.

The r value per inch for different types of insulation varies depending on the. While there are additional considerations such as venting and moisture problems to take into account when you insulate under floors the united states department of energy recommends an r 25 rating in cold climates and an r 11 in warmer parts of the country.