Garage door insulation is an extra layer of material that prevents heat transfer through the garage door. We'll cover the most common insulating garage door materials in the next section. Garage door insulation is graded according to the R-value rating system, which measures the effectiveness of the material in blocking heat from passing through the insulation.
The R-value rating for garage door insulation is a good rule of thumb when determining the level of insulation you need. However, not all manufacturers use the same method to assign R-values to their products, so ratings are not absolute. It's still a good idea to find out what materials your garage door is constructed from and base your decision on those facts. You can learn more about home insulation and R-values from the Department of Energy.
