Spray Foam vs Fiberglass Insulation
A complete comparison to help you make the best insulation decision for your Wisconsin home or building.
The Two Most Common Insulation Types
When it comes to insulating your home, garage, pole barn, or commercial building in Wisconsin, the two most common options are spray foam insulation and fiberglass batt insulation. While fiberglass has been the standard for decades, spray foam has proven to be far superior in almost every measurable category.
R-Value: The Insulation Metric That Matters
R-value measures an insulation material's resistance to heat flow. The higher the R-value per inch, the better the insulation performs.
- Closed-cell spray foam: R-6.5 to R-7 per inch
- Open-cell spray foam: R-3.5 to R-3.8 per inch
- Fiberglass batts: R-2.2 to R-3.8 per inch
Closed-cell spray foam delivers nearly double the insulating value of fiberglass in the same thickness. This means you get better performance without losing interior space.
Air Sealing: The Critical Difference
This is where spray foam truly separates itself from fiberglass. Fiberglass batts must be carefully cut and fitted around every pipe, wire, and structural member, and even the best installation leaves gaps. Air flows freely through and around fiberglass, carrying heat with it.
Spray foam expands on contact to fill every crack, gap, and cavity. It creates a continuous, seamless air barrier that stops air movement completely. According to the Department of Energy, air leakage accounts for 25-40% of energy used for heating and cooling in a typical home.
Moisture Protection
Fiberglass absorbs moisture, which destroys its insulating ability and creates conditions for mold growth. When wet, fiberglass can sag and compress, permanently reducing its effectiveness.
Closed-cell spray foam is a moisture and vapor barrier by itself. It doesn't absorb water, won't support mold growth, and continues to perform even in humid conditions. This is especially important in Wisconsin, where temperature swings create condensation risk in walls and attics.
Longevity and Durability
Fiberglass batts degrade over time. They sag, settle, and lose R-value as they age. Rodents nest in fiberglass. Moisture compresses it. Over 10-15 years, fiberglass insulation can lose a significant portion of its original performance.
Spray foam maintains its performance for the life of the building. It doesn't sag, settle, or degrade. Once installed, it provides consistent insulation performance decade after decade.
Cost Comparison
Fiberglass insulation costs less upfront than spray foam. However, when you factor in the long-term energy savings, reduced air leakage, and permanent performance of spray foam, the total cost of ownership is often lower with spray foam over the life of the building.
As an owner-operated business with the lowest overhead in northwestern Wisconsin, Smart Foam LLC offers spray foam insulation at the most competitive prices in the Eau Claire area. We make professional spray foam insulation accessible and affordable.
The Bottom Line
For Wisconsin homeowners and builders who want the best insulation performance, especially in garages, pole barns, attics, and new construction, spray foam is the clear winner. It outperforms fiberglass in R-value, air sealing, moisture protection, and longevity.
Contact Smart Foam LLC today for a free estimate and see how affordable the best insulation can be.