The r value equates to the thermal resistance of a material. Essentially this typing breaks down the main components which make something resistant to changes in temperature. These components are: Type of insulation, Thickness, Density, Temperature, Aging, Moisture accumulation. These all come together to form a single R-rating, making it easier for customers to choose which is the better option available to them. Bear in mind that each R-rating is individual to each layer, so you may need to add together the R-values to find the correct, total rating of your insulation. The R-value is also completely dependent on correct installation, so bear this in mind when fixing your new insulation to your garage door. Always follow the instructions exactly as described or get a pro in to help you install your new garage door insulation kit. In order to choose the best variant, try to go for the highest number available, that is still cost-effective for your budget. Some kits will also come with what is known as U-value. This indicates how well a material conducts heat or allows the passage of heat. Unlike the R-value, when using the U-value, you’ll want to look for the lowest number possible for your door insulation, since you don’t want the insulation to allow for heat transference.