US Department of Energy
National Laboratory System
Science and Technology Information
The following shows the equivalent "R" values of the most common types of insulation.
When insulation collects moisture or any air is allowed to pass through it the "R" value
goes to zero.
Fiberglass Insulation R 3.2 per inch 32% Efficiency Rating
3 1/2 inches in a 2x4 wall with a 32% ER is equivalent to R11.2
Collects moisture
Cellulose Insulation R 3.5 per inch 36% Efficiency Rating
3 1/2 inches in a 2x4 wall with a 34% ER is equivalent to R12.74
Collects moisture
Open Cell Foam Insulation R 3.5 per inch 44% Efficiency Rating
3 1/2 inches in a 2x4 wall with a 44% ER is equivalent to R13.72
Closed Cell Foam Insulation R 7 per inch 92% Efficiency Rating
3 1/2 inches in a 2x4 wall with a 92% ER is equivalent to R 63.7
2 inches in a 2x4 wall with a 92% ER is equivalent to R 40.18 1 inch in a 2x4 wall with a 92% ER is equivalent to R20.09 Does not collect moisture
Efficiency Foam Insulation
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Kenny Caldwell
Cell Phone: 770-875-0417