Desired R Value For Attic

Existing 3 4 inches of insulation.

Desired r value for attic.

For houses in a southwestern state or other areas with generally warmer temperatures you might need attic insulation with an r value of only r 30. The recommended r value for attic floor insulation for this house is r 38. Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. It will most likely be a fiberglass batt so multiply the thickness in inches by 3 2 to find out the r value or the r value might be visible on a product label.

If the insulation is a foam board or sprayed on foam use any visible label information or multiply the thickness in inches by 5 to estimate the r value. For houses in the northeastern united states or other colder areas you might need attic insulation with an r value as high as r 60. Add insulation to attic. Your home s age if your home is more than 10 year old you likely need more insulation.

If the existing attic floor insulation has an r 11 insulation value then an additional r 27 would be needed to bring the attic floor insulation up to the level recommended for that house. The homeowner could then check table 1 to find several choices. You will need a higher r value of insulation if you live in the northeast than if you live in southern california. Recommended insulation levels for retrofitting existing wood framed buildings.

Where you live different climates require different insulation r values.