R-value is the measurement of how resistant insulation is to hot or cold air passing through. The "R" in R-value stands for resistance. The higher the insulation R-value, the better the insulation works. The amount of R-value you need depends on the project at hand. When your local Dr. Energy Saver dealer comes out to inspect your home, they will determine the best amount of R-value for you. To learn more about R-value, contact your local Dr. Energy Saver dealer.