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How Much Insulation Do I Need in My Attic?

Finished residential attic with work desk and chair.

Your attic is one of the main places in your home that needs insulation. Since you normally don’t have heating and cooling in your attic, insulation helps keep it cool in the summer and warm in the winter ― and more importantly, it helps maintain the comfort of the rest of your home. But do you know how much insulation your attic needs, or if you have enough? You may have had the same insulation for years without knowing the benefits of adding more.

How to Know You Need More Attic Insulation

Some signs that your attic may need more insulation include:

  • Difficulty keeping your home warm during the winter
  • Difficulty keeping your home cool during the summer
  • Cold spots in your home
  • Drafts even though all your doors and windows are closed
  • Mice and bugs in your home
  • Water leaks in your attic

Types of Insulation

Once you’ve determined your attic needs more insulation, you’ll need to determine the best type of insulation for your needs. This depends largely on your home’s layout and your specific comfort and insulation needs. Insulation for attics in Northern Illinois should have a minimum R-value of R-49, equivalent to 16 inches of fiberglass insulation. Some insulation options include:

  • Loose fiberglass insulation: 2.2 to 2.9 R-value per inch
  • Batt fiberglass insulation: 2.9 to 3.8 R-value per inch
  • Cellulose insulation: 3.1 to 3.8 R-value per inch
  • Stone wool insulation: 2.2 to 3.3 R-value per inch
  • Cotton insulation: 3.0 to 3.7 R-value per inch
  • Cementitious insulation: 2.0 to 3.9 R-value per inch
  • Polyicynene insulation: 3.6 to 4.3 R-value per inch
  • Phenolic insulation: 4.4 to 8.2 R-value per inch
  • Polyisocyanurate insulation: 5.0 to 8.0 R-value per inch
  • Polyurethane insulation: 5.6 to 8.0 R-value per inch

The professionals at ThermaSeal/Lakeside Insulation are highly knowledgeable and experienced with all types of insulation. We can determine the best type of insulation for your attic and comfort needs. One of our pros can also determine the R-value you already have, which is important to know when adding more insulation. You can also determine your current R-value yourself by determining what type of insulation you have and its R-value per inch, then measuring the depth of your current insulation. For example, if you have 10 inches of loose fiberglass insulation, you have a maximum R-value of 29 ― not enough for an attic in this climate.

It’s important to note that the R-value suggested is only accurate if the insulation is in good condition. If moisture and pests have damaged your insulation, it will reduce the R-value. A professional can assess your current insulation and any potential damage to determine your actual R-value, how much additional insulation is needed and whether you can keep some or all of the existing insulation.

Trust ThermaSeal/Lakeside for an Insulated Attic

If you think you may need more insulation for your attic, you can rely on the team at ThermaSeal/Lakeside Insulation to provide you with knowledgeable information, expert services and quality results. We work with a wide variety of insulation types and know which will give your attic the best results and provide your home with optimal comfort.

To set up attic insulation services, give ThermaSeal/Lakeside Insulation a call at (800) 836-2535, or contact us online now.

Products We Install

Our team installs both batt and blown-in fiberglass insulation.


Help prevent mold and excessive moisture infiltration in homes you build with our waterproofing services.


At Thermaseal / Lakeside Insulation, we understand the role a floor plays within a building system by controlling sound and fire.

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