What Is R-Value?
Insulation maintains temperature. It really is that simple. If you introduce heat, that heat is not allowed to escape quickly when it is bound by insulation. It also maintains cold. This is called “resistance.” The insulation resists the travel of heat or cold from inside the structure.
R-value is the measurement of the resistance. Different insulating materials have different R-Values. Here is a list of common insulation materials and their R-Value per inch:
Material | R-Value per inch (approx) |
---|---|
Foam: Closed Cell | 6.5-7 |
Foam: Open Cell | 3.8 |
Mineral Wool | 3.5 |
Fiberglass | 3.5 |
Cellulose | 3.5 |
ICC building codes determine how much R-value is required in buildings throughout the US. Here is a chart which shows how much R-Value is required: