Properly insulating your attic can slash your energy bill by up to 20% monthly, and provide you with a host of benefits year-round, including the increased comfort of consistent temperatures in your home. When consulting with a professional about how to optimize your insulation, however, it’s important to have some basic information at hand about the current state of your insulation as a point of reference.
That’s where R-values come in. The following tips will help you understand what an R-value is, how to figure yours out, and how to use that information to have a productive conversation with a trusted professional about maximizing your attic’s insulation.
What is an R-value?
R-values are a way of expressing how efficient insulation is. It measures the insulation’s thermal resistance—in other words, its ability to resist heat and protect against heated air passing through its barrier. The higher your insulation’s R-value, the better the job it will do of keeping heated air from passing through.
In the winter, insulation with a higher R-value will more effectively keep heated air from escaping through the roof to the outside, making for more efficient home heating. In the summer, it will more effectively keep the heated air outside from coming into the house, increasing the efficiency of your home cooling system.
What should your attic insulation’s R-value be?
The Department of Energy (DOE) has established recommendations for the optimal R-value of insulation for different areas of the home—attic, walls, floors, and crawlspaces—depending on the region of the country you live in.
For the state of Pennsylvania, the recommended R-value for attic insulation is between R38 and R60. And since the DOE estimates that only 20% of homes built before 1980 are well insulated, there’s a good chance your home is not yet insulated at the recommended level.
How do you figure out your R-value?
While determining the exact R-value of your current insulation can require some fairly involved calculation, you can get a very good estimate to work from simply by multiplying the number of inches of insulation you have by a factor corresponding to the type of insulation.
Most types of insulation will be labeled with their R-value factor, but generally speaking, you can use a factor of 2.2 to 2.9 for blown fiberglass, 2.9 to 3.8 for fiberglass batting, 3.1 to 3.58 for blown cellulose, 2.2 to 3.3 for loose rock wool, and 3.6 to 8.2 for sprayed foam.
Once you know your R-value, you have a vital piece of information about your starting point to use in a conversation with an insulation professional. From there, you can work together to find the best and most cost-effective way to maximize your attic’s insulation!