What temperature do the 2.2 2.5 and 2.8 r-value blankets maintain?

The R-Value is a measurement of how well heat is kept underneath the blanket. There are no specific temperatures that the various R-Values maintain, because there are many factors that impact their performance. A R2.2 will keep concrete about 15–20°F higher than outside, A R2.5 20°F - 25°F higher, and a R2.8 25–30°F higher. These numbers are not guaranteed as outside ambiance can impact performance.