How to Check Your Home’s Attic Insulation Level

Low attic insulation levels and air leaks result in energy waste, and discomfort in your home during the summer and the winter. What’s more, a home with low insulation levels could easily have utility bills that are 10% higher than a home that is well-sealed and insulated.

So, how do you know if you have enough attic insulation? Here are some basic steps on how to check:

Step 1: Access Your Attic

If you have stairs or a set of pull down-stairs going to your attic, you have it easy. However, if you just have an attic hatch or cover, you may need a ladder. You should also bring a flashlight, a ruler or tape measure, and your cell phone to get a quick picture.

You do not need to get all the way into your attic. If you can see and reach the insulation on the floor from the attic hatch, that is enough. If not, you may need to crawl inside the attic to reach the insulation.

In homes, with no attic, the insulation is placed right up against the roof deck. When the insulation is covered with drywall it is called a “cathedral ceiling." If that is the case, hire an energy auditor or insulation contractor to check how much insulation is in the space between your ceiling and the roof and if it can be added there if needed.

Step 2: Check Your Attic Floor

Quick Visual Check of Insulation Levels

  • When looking across your uncovered attic floor, if the insulation is at or below the level of the attic floor joists,you probably need to add more insulation.

Measuring Insulation Levels

  • Use a measuring tape/ruler to measure the depth of the insulation (inches). You will want to record your measurement so you can determine how much more insulation you need to achieve the recommended levels.
Graphic displaying recommended levels of insulation and R-values.

Since most common insulation types (fiberglass, cellulose, mineral wool) have an R-value of about 3 – 3.5 per inch it is easy to estimate how much R-value the insulation your attic currently has. Just take the depth in inches x 3 to get an estimated value.

If you live in the Southern part of the U.S., the recommended insulation level is a minimum of R-38 or about 13-14 inches of insulation. If you live in the Northern part of the U.S., the recommended insulation level is a minimum of R-49 or about 16-18 inches of insulation. By subtracting the amount of insulation you have from the recommended level where you live, you can calculate how much you need to add.

If your insulation levels are more than 4-6 inches below the recommended level (or your attic floor joists are not buried) you should consider adding more to improve the comfort and energy efficiency of your home.

Next: Hire a contractor.

Author: Doug Anderson, ENERGY STAR Certified Products