What’s the Difference? Spray Foam Insulation Cost vs. Fiberglass Insulation Cost – Bob Vila

If you’ve ever opened your utility bill and needed several deep breaths (and possibly a paper bag), insulationor the lack of itmight be to blame. Home insulation is one of the biggest factors in heating and cooling efficiency, yet it’s also one of the most overlooked. When homeowners finally decide to upgrade or build, the most common question pops up: Should I choose spray foam insulation or fiberglass insulationand what’s the cost difference?

As it turns out, the difference isn’t just the price tag. It’s performance, longevity, energy efficiency, and how much you enjoy (or despise) dusty pink batts. Below, we break down everything you need to know about spray foam vs. fiberglass costsso you can choose the right option without second-guessing your wallet.

Understanding the Basics: Spray Foam vs. Fiberglass

What Is Spray Foam Insulation?

Spray foam insulation is a two-part chemical mixture that expands when applied, filling cracks, voids, and tight spaces like an overachieving marshmallow. It comes in two types:

• Open-cell spray foam – lighter, slightly less insulative, great for sound dampening.
• Closed-cell spray foam – denser, higher R-value, works as an air and moisture barrier.

Spray foam is known for its impressive energy efficiency, making it a favorite of homeowners who want to seal their house up tighter than a pickle jar.

What Is Fiberglass Insulation?

Fiberglass insulation is the stuff you’ve seen in attics and walls that looks like cotton candy but definitely shouldn’t be tasted. Made from tiny glass fibers, it’s affordable, easy to install, and comes in two main forms:

• Fiberglass batts – pre-cut, ready-to-roll blankets.
• Loose-fill fiberglass – blown in with a machine to cover attic floors and irregular spaces.

It’s the classic choice because it works well enough and won’t empty your bank account.

Spray Foam Insulation Cost: What to Expect

Spray foam is the pricier option, but it may provide long-term savings through improved energy efficiency. Here’s a cost breakdown based on national averages:

• Open-cell spray foam: $0.50–$1.50 per board foot
• Closed-cell spray foam: $1.00–$2.90 per board foot
• Total installation cost for a typical home: $8,000–$20,000+

These prices vary depending on climate zone, project complexity, and whether you’re insulating walls, attics, crawl spaces, or the entire home. Closed-cell foam costs more because it offers nearly double the R-value per inchand it acts as both an insulator and a vapor barrier, reducing the need for additional materials.

Why Spray Foam Costs More

• Higher material cost – It’s a chemically reactive product with specialized manufacturing.
• Professional installation required – The equipment is expensive, and safety training is essential.
• Superior performance – It seals air leaks exceptionally well, improving HVAC efficiency.
• Moisture resistance – Closed-cell foam helps prevent mold growth in damp areas.

While the upfront cost may sting, spray foam often pays for itself over time through lower utility bills and better comfort.

Fiberglass Insulation Cost: Budget-Friendly and Reliable

Fiberglass remains the most common insulation for one big reason: affordability. Here’s what you can expect to pay:

• Fiberglass batts: $0.40–$1.20 per square foot
• Blown-in fiberglass: $1.00–$2.80 per square foot
• Total installation cost for a typical home: $3,000–$10,000

If you’re insulating an attic or interior walls during a remodel, fiberglass is a cost-effective solution that doesn’t require advanced equipment.

Why Fiberglass Costs Less

• Lower material cost – It’s inexpensive to manufacture.
• DIY-friendly – Batts can be installed by homeowners with basic tools.
• Fast installation – Larger areas can be completed quickly.

However, fiberglass does not seal air gaps, and its performance depends heavily on proper installation. Gaps, compression, or misalignment can reduce its effectiveness.

Cost Comparison: Spray Foam vs. Fiberglass

The clearest difference between the two lies in cost per square foot. Let’s compare side-by-side:

Spray foam clearly costs more but offers better performance and longevity. Fiberglass is easier on the budget but less efficient long term.

Energy Efficiency: What You Save Later

Upfront cost tells only half the story. Spray foam’s ability to reduce air leakage often leads to 20–40% lower monthly energy bills in many climates. For homeowners in cold regions or areas with extreme temperature swings, this savings can be significant.

Fiberglass can still improve energy efficiency when installed correctly, but it doesn’t stop drafts. If your home is older or drafty, you may need additional air sealing to get the best results.

Moisture Control: A Critical Factor

Closed-cell spray foam offers moisture resistance, making it a strong option for basements, crawl spaces, and coastal climates. Its rigid structure helps prevent condensation, reducing mold risk.

Fiberglass, on the other hand, can trap moisture if exposed to leaks or humid air. Wet fiberglass loses its insulating power and may require replacement.

Installation Complexity

Spray Foam

This is always a professional job due to chemical handling, ventilation requirements, and the need for specialized equipment.

Fiberglass

Homeowners can install batts themselves, but blown-in fiberglass usually requires professional equipment. Precision is important: small installation errors reduce performance.

Which One Is Better for Your Home?

Choose Spray Foam If:

• You want maximum energy efficiency
• Your climate has extreme cold or heat
• You have air leakage issues or drafty rooms
• You want long-term performance with minimal maintenance

Choose Fiberglass If:

• You need a budget-friendly solution
• You’re insulating a large area quickly
• You prefer DIY installation
• Your home has good air sealing already

Real-World Example: Cost Breakdown

Let’s say you need to insulate a 2,000-square-foot home:

• Spray Foam (Closed-Cell): $12,000–$25,000
• Spray Foam (Open-Cell): $8,000–$16,000
• Fiberglass Batts: $3,000–$6,500
• Blown-In Fiberglass: $4,000–$8,000

Savings over 10 years can vary widely, but homeowners often recover the cost of spray foam through energy reductionsespecially in climates with high heating and cooling demands.

Conclusion

Spray foam insulation costs more upfront but delivers superior long-term performance, higher R-values, and better air sealing. Fiberglass insulation remains the more budget-friendly choice and is still effective when installed properly. Ultimately, the right choice depends on your climate, budget, energy goals, and whether you plan to DIY or hire a pro.

500-Word Experience Section: What Homeowners Learned About Insulation Costs

Over the years, homeowners across the U.S. have shared plenty of real-world experiences about choosing between spray foam and fiberglass insulationsome enlightening, some humorous, and some “I wish I had known that sooner!” moments. Here are insights from typical scenarios that mirror what thousands of homeowners experience.

One common story involves homeowners who initially opted for fiberglass because of its affordability. “We were renovating the attic and thought fiberglass batts would be good enough,” one homeowner said. “The installation was easy. The real issue showed up months later. The rooms were still drafty, and the winter heating bill didn’t budge much.” After contacting an insulation contractor, they discovered unsealed gaps around rafters and recessed lighting fixturesgaps fiberglass can’t seal on its own. They eventually upgraded to open-cell spray foam in key areas and noticed a dramatic improvement in temperature consistency and monthly heating bills.

Another homeowner in a coastal region said moisture was the deciding factor. “Fiberglass was cheaper, but our crawl space stayed damp. We realized fiberglass could absorb that moisture, making it useless.” They chose closed-cell spray foam for that area and reported that humidity levels dropped significantly. Over time, the foam’s rigidity also strengthened the floor structure, a bonus they didn’t expect.

Some homeowners took the DIY route. “We insulated our detached garage using fiberglass batts,” a Wisconsin homeowner said. “It was straightforward, and the cost was under $1,000.” But they quickly learned that garage doors and wall gaps needed sealing to match the insulation’s effectiveness. They paired the fiberglass with spray foam cans for sealing gaps, improving overall performance without the high cost of full spray foam installation.

However, homeowners who invested in whole-house closed-cell spray foam often shared the most glowing reviews. “It was expensivearound $20,000,” one homeowner admitted. “But the difference was immediate. Our HVAC system didn’t have to run nearly as often, the house felt quieter, and our energy usage dropped dramatically.” Many commented that the insulation essentially “modernized” older homes by improving comfort and energy efficiency to new-construction standards.

Contractors frequently advise homeowners to consider their climate before choosing insulation. People in northern states like Minnesota, Michigan, and Maine often see more dramatic payback from spray foam because of long, harsh winters. Meanwhile, homeowners in moderate climates sometimes stick with fiberglass and improve air sealing as a compromise.

One insightful takeaway is that insulation is not a one-size-fits-all solution. Spray foam is ideal for sealing irregular spaces, controlling moisture, and improving structural rigidity. Fiberglass is great for uncomplicated areas, budgets, and large square footage where quick coverage is needed. Many homeowners combine both materials to maximize valuespray foam for attics, rim joists, and crawl spaces, and fiberglass in interior walls or floors where moisture and air leakage are less critical.

After comparing experiences, one theme emerges: the “best” insulation depends heavily on your home’s needs, climate, and long-term priorities. Spending more upfront sometimes results in substantial savings and comfort improvements, but budget-friendly solutions can still work well with proper installation and air sealing.

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