How Thick Should Blown-In Insulation Be?
One of the most common questions we get at Premier North Insulation is:
“How thick should blown-in insulation be in my attic or walls?”
The answer depends on a few key factors—your location, the part of your home you’re insulating, and the type of insulation being used. But getting the thickness right is critical. Too little insulation means lost energy, higher bills, and uncomfortable living spaces—especially in Wisconsin’s extreme climate.
Blown-In Insulation: Why Thickness Matters
Blown-in insulation works by trapping air within tiny pockets to slow down heat transfer. The thicker the insulation layer, the better it performs—measured in R-value, which stands for thermal resistance.
Each inch of insulation contributes to a higher R-value. But different materials have different R-values per inch:
| Insulation Type | R-Value per Inch |
|---|---|
| Cellulose | R-3.2 to R-3.8 |
| Fiberglass (loose-fill) | R-2.2 to R-2.7 |
| Mineral Wool | R-3.0 to R-3.3 |
Recommended Insulation Thickness for Wisconsin Homes
Wisconsin falls into climate zone 6, meaning colder winters and the need for high insulation levels, especially in the attic.
👉 Attic Insulation (Unfinished Attic)
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Recommended R-value: R-49 to R-60
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Required Thickness:
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Fiberglass: 18–22 inches
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Cellulose: 13–16 inches
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👉 Attic Insulation (Already Has Some Insulation)
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Add blown-in insulation on top to reach R-49 minimum
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Measure existing insulation and add enough to reach target R-value
👉 Wall Cavities
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Recommended R-value: R-13 to R-21 (depending on wall depth and material)
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Walls typically allow for 3.5″–5.5″ of insulation in a standard 2×4 or 2×6 cavity
Signs Your Insulation Isn’t Thick Enough
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Cold drafts in winter or hot spots in summer
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High energy bills
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Uneven room temperatures
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Ice dams on the roof
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Visible joists in the attic (a sign insulation is too low)
Let Premier North Insulation Get the Thickness Right
At Premier North Insulation, we don’t guess—we measure. Our team provides free home assessments, inspects your current insulation levels, and recommends exactly how much blown-in insulation you need for maximum efficiency and comfort.
We use high-performance cellulose and fiberglass products and install insulation to meet or exceed ENERGY STAR® and local building code requirements.
Why Homeowners Trust Premier North Insulation
✅ Local expertise in Milwaukee, Waukesha & beyond
✅ Honest, accurate R-value recommendations
✅ Clean, professional blown-in insulation installation
✅ Licensed, insured, and certified team
✅ Access to rebates through Wisconsin’s Focus on Energy program
Schedule Your Free Insulation Estimate Today
Don’t let under-insulated attics or walls drive up your energy bills. Trust Premier North Insulation to get the job done right—with the right materials, the right thickness, and long-lasting results.
