R-value is a term often used in home construction to determine the level of heat resistance in products including insulation, roofing, garage doors, etc. The basic concept is that the higher the R-value the better the product is at keeping your home warm or cool.
When it comes to garage doors, R-value can be incredibly important. The first question to ask is how you are planning to use your garage. Are you storing valuables? Are you using it as a living space or working space? Or are you simply parking vehicles inside? Is the rest of the garage insulated?
If you have reason to want to keep it warm in the cooler months and cooler in the warm months than you will want a higher R-value. If you are not concerned with the temperature inside your garage then you can afford to purchase a garage door with a lower R-value.
It is also important to keep in mind that your garage temperature can have an effect on the rest of your home. Also, garage doors with higher R-values are typically higher in stability and dent resistance. R-value is only one factor to consider in deciding the garage door that is best for your home.