New jersey ( NJ ) polyurethane spray foam insulation R-Value , Weather Tight Foam Insulation Corp- New Jersey NJ Spray Foam Contractor

Benefits of polyurethane spray foam insulation:

R value

The R-value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux

(heat transfer per unit area) through it or $R = \Delta T/\dot Q_A$

The R-value being discussed is the unit thermal resistance.

Below is a comparison between R Value to different insulation materials per Inch thickness.

Fiber Glass R-3.5 per Inch
Cellulose R-3.5 per Inch
Cotton R-3.5 per Inch
Rock Wool R-3.5 per Inch
Open Cell polyurethane Foam R-3.5 ~ R-3.9 per Inch
Closed Cell polyurethane Foam R-6.0 ~ R-7 per Inch

Clearly polyurethane Closed cell foam has the most R-value available in any insulations known today.