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June 3, 2025

Understanding Insulation R-Values

When it comes to insulating your home, one of the most important—and misunderstood—factors is the R-value. This simple number has a major impact on your home’s comfort, energy efficiency, and heating and cooling costs. At Koala Insulation of Northern Illinois, we’re committed to helping homeowners make informed decisions about insulation, starting with a clear understanding of what R-value means and why it matters.


What Is R-Value?

R-value stands for “resistance to heat flow.” It’s a measurement of how well insulation can resist the transfer of heat. The higher the R-value, the greater the insulating power.

Essentially, insulation with a higher R-value provides better thermal resistance, helping keep warm air inside during the winter and outside during the summer. R-value is a key factor in determining how energy-efficient your home will be once insulation is installed or upgraded.


How Is R-Value Calculated?

R-value is determined by several factors, including:

  • Material Type: Different insulation materials (like fiberglass, spray foam, or cellulose) have different natural insulating properties.
  • Thickness: The thicker the insulation, the higher the R-value—up to a point. Packing insulation too tightly can actually reduce its effectiveness.
  • Density: Denser materials can offer better thermal resistance, especially in smaller spaces.
  • Installation Quality: Poorly installed insulation, even with a high R-value rating, may not perform as expected.

At Koala Insulation of Northern Illinois, we help you choose the best type and amount of insulation for your home based on climate, building structure, and energy goals.


Recommended R-Values for Northern Illinois

Northern Illinois experiences cold winters and hot, humid summers. That means insulation must perform year-round to help homeowners maintain comfort and reduce energy bills.

According to the U.S. Department of Energy, here are the recommended R-values for homes in climate zone 5 (which includes Northern Illinois):

  • Attic (Uninsulated): R-49 to R-60
  • Attic (Existing Insulation): Add enough to reach R-49 to R-60
  • Wall Insulation (2×4 Walls): R-13 to R-15
  • Wall Insulation (2×6 Walls): R-19 to R-21
  • Floors and Crawl Spaces: R-25 to R-30
  • Basement Walls: R-11 to R-15 (interior), R-19 (exterior foam board)

Whether you’re insulating a new home or upgrading existing insulation, our team at Koala Insulation of Northern Illinois ensures your home meets or exceeds these guidelines.


Understanding R-Value by Insulation Type

Let’s take a closer look at how different insulation materials compare in terms of R-value:

1. Fiberglass Batts

  • R-Value: ~R-2.9 to R-3.8 per inch
  • Commonly used in walls, attics, and floors
  • Cost-effective and widely available
  • Performance depends on proper installation

2. Blown-In Fiberglass

  • R-Value: ~R-2.2 to R-2.7 per inch
  • Ideal for attic floors and hard-to-reach spaces
  • Can be layered to reach higher R-values

3. Cellulose (Blown-In or Dense Pack)

  • R-Value: ~R-3.2 to R-3.8 per inch
  • Excellent for filling irregular spaces
  • Higher density than fiberglass and eco-friendly

4. Spray Foam Insulation

  • Open-cell: ~R-3.5 to R-3.8 per inch
  • Closed-cell: ~R-6.0 to R-7.0 per inch
  • Acts as both insulation and air barrier
  • Great for crawl spaces, attics, rim joists, and basements

5. Rigid Foam Board

  • R-Value: ~R-4 to R-6.5 per inch
  • Ideal for basement walls, attic hatches, and under-slab insulation
  • Moisture-resistant and easy to cut to size

At Koala Insulation of Northern Illinois, we guide you in selecting the right material and R-value based on your project area, moisture conditions, and insulation goals.


Does Higher R-Value Always Mean Better?

Not necessarily. More isn’t always better. The goal is to achieve balanced insulation performance, which depends on where and how insulation is installed.

Adding extra insulation beyond the recommended R-values may not always result in significant energy savings. Instead, it’s more effective to combine insulation with air sealing, moisture control, and ventilation. Our team uses a holistic approach to maximize your home’s efficiency.


The Importance of Proper Installation

Even high R-value insulation won’t perform if it’s installed incorrectly. Common installation issues include:

  • Gaps and compression
  • Poor air sealing
  • Uneven distribution
  • Inadequate moisture protection

At Koala Insulation of Northern Illinois, we use best-in-class tools and techniques to ensure insulation is installed professionally and performs as rated. Our insulation specialists are trained to evaluate your home’s existing insulation, identify weak points, and install new insulation with precision.


Energy Savings and Comfort

The right R-value in the right place can significantly reduce your home’s heating and cooling bills. According to Energy Star, sealing and insulating your home can save you up to 15% on heating and cooling costs, and in some cases even more.

Beyond energy savings, the benefits of properly rated and installed insulation include:

  • Improved indoor comfort: Less temperature fluctuation, fewer drafts
  • Better air quality: Reduced allergens and pollutants
  • Increased HVAC efficiency: Less wear and tear on your system
  • Sound control: Quieter indoor spaces, especially in multi-level homes

Trust Koala Insulation of Northern Illinois

Choosing the right insulation R-value for your home doesn’t have to be confusing. At Koala Insulation of Northern Illinois, we help homeowners make informed decisions that improve comfort, reduce energy use, and boost long-term home value.

We offer:

  • Free insulation evaluations
  • Tailored recommendations based on your home’s needs
  • Professional installation of fiberglass, spray foam, cellulose, and more
  • Air sealing and moisture control for full system performance
  • Friendly, knowledgeable service from local experts

Call Us Today for a Free Estimate

Understanding R-values is the first step toward creating a more energy-efficient and comfortable home. Whether you’re updating old insulation, sealing air leaks, or building new, Koala Insulation of Northern Illinois is here to help.

Call us today at (847) 563-7811 or visit https://koalainsulation.com/Northern-Illinois to schedule your free estimate. Let’s get your home insulated the right way—backed by experience, precision, and local expertise.

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