Attic insulation can be a tricky subject. After all, the amount of insulation you need varies depending on the year your house was built and where you live, meaning there’s no one-size-fits-all solution. Unfortunately, homes insulated prior to 2007 are now considered outdated by current standards.
To help you stay ahead of the curve, we’re here to help you understand how much insulation is ideal for specific areas so you can ensure your home has the perfect amount of insulation.
Determine How Much Insulation You Have
Before you can calculate how much attic insulation you require, you need to determine how much you already have.
Figuring this out is as easy as grabbing a ruler and measuring how deep your current insulation goes. Take the ruler and extend it from the top of the fill to the floor, then note the measurement you get.
Is Your Attic Uninsulated?
An uninsulated attic will need insulation with a higher resistance value. This is known in the field as an R-value.
What Is R-Value?
R-value provides a threshold for measuring insulation’s resistance to heat. Using insulation with the appropriate R-value will keep your home at the desired temperature while using as little energy as possible. Each geographic area and home is different, so different R-values allow for precise calibration within different climates and home styles.
The number is determined when the insulation is tested in a laboratory. Higher numbers mean the insulation is more effective at keeping heat from passing through.
However, higher numbers don’t necessarily mean the insulation is better. Instead, it indicates how that specific type of insulation will perform in a particular region.
Find Out What Zone You Live In
To determine the optimal R-value for your location, you need to know what zone you live in. This is as easy as looking at the Energy Star map and pinpointing where you live. The map divides the country into neat, color-coordinated zones.
Once you know your zone, head to the Department of Energy's website and use their insulation calculator to get a more precise calculation.
If you live in Zone 1, the average minimum insulation requirement is 9 inches of R30 fill. However, the average recommended level is 14 inches of R49.
For Zone 2, the average minimum level is 9 inches of R30 fill, while the average recommended level is 17 inches of R60 fill.
For Zone 3, the average minimum requirement is 9 inches of R30 fill, while the average recommended level is 17 inches of R60 fill.
The average minimum for Zone 4 is 11 inches of R38, while the average recommended level is 17 inches of R60, the same as Zones 2 and 3.
The average minimum and average recommended levels for Zone 5 are the same as Zone 4: 11 inches of R38 fill and 17 inches of R60, respectively.
In Zone 6, the average minimum requirement is 16 inches of R49 fill, and the average recommended level is 17 inches of R60.
Zone 7 carries an average minimum requirement of 14 inches of R49 fill and an average recommended level of 17 inches of R60 fill.
What About Foam Insulation?
Foam insulation is an alternative to traditional fiberglass insulation. It’s constructed from polyurethane and is available in closed-cell and open-cell configurations. Closed-cell insulation blocks airflow entirely, while open-cell is slightly thinner and can be used for both insulation and sound reduction.
Get Started Today
Now that you know a little more about how much insulation your attic requires, you’re ready to start sourcing materials to get your project going!