Have you ever wondered if spray foam or fiberglass fits your home best? In most cases, spray foam wins for sealing and savings, but fiberglass still works when budget or DIY matters. Read on to see which one makes sense for you.
Did you know that homeowners can cut heating and cooling costs by up to 15% just by sealing leaks and adding proper insulation?
In this guide on Spray Foam vs. Fiberglass, we’ll look at key points so you can choose the right option. We’ll share real stats, simple examples, and a brief stat right away: Gorilla Building notes that just 2 inches of spray foam can block 92% of heat transfer and cut air leaks by 85% in many cases.
This matters because a tight seal often means lower bills and fewer drafts. Let’s explore into what each insulation does, costs, and how it feels in real homes.
Comparing Insulation Basics: Spray Foam Options vs. Fiberglass Fundamentals
What Is Spray Foam Insulation?
- Spray foam is a mix applied on-site. Two main types: open-cell and closed-cell.
- Open-cell feels softer and expands more; R-value around 3.5 per inch. It offers some air sealing but is more vapor-open.
- Closed is denser, R-value near 7 per inch, and acts as a moisture barrier.
- Pros: Fill gaps and seal cracks, so you get fewer drafts. It sticks to surfaces, so walls or attic joints stay covered.
- Cons: higher upfront cost, needs a trained crew and special gear.
What Is Fiberglass Insulation?
- Common types: batt (batts fit between studs or joists) and blown-in (loose-fill in attics or irregular spaces).
- R-value per inch is around 3.2. Install is simpler: many homeowners buy rolls and fit them.
- Pros: lower material cost, DIY-friendly if you use proper gear (gloves, mask).
- Cons: gaps if cut poorly or settled over time, less air sealing, fibers may irritate skin or air if disturbed.
Performance Factors: Energy Savings, Moisture Control & Air Sealing
R-Value and Thermal Performance
- R-value shows resistance to heat flow. A higher R-value means better resistance. Closed-cell spray foam gives a high R-value in less space. Fiberglass needs thicker layers to match.
- In many homes, adding more fiberglass can help, but sealing leaks may still leave drafts.
Air Leakage & Airtight Seal
- Spray foam seals small gaps and cracks automatically as it expands. This can cut drafts and reduce the load on HVAC.
- Fiberglass alone won’t seal gaps, and air moves around it unless you add caulk or foam board sealing first. In a mild climate, extra sealing steps may be OK; in extreme heat or cold zones, a tight seal pays off more.
Moisture Barrier & Mold Prevention
- Closed-cell spray foam often acts as a vapor barrier, reducing moisture entering walls or attic. This can help avoid mold or rot in humid areas.
- Fiberglass needs a separate vapor barrier (e.g., plastic sheeting). If that barrier has gaps or tears, moisture can collect in batts and lead to mold.
- Real-life example: A Jackson homeowner had repeated attic mold behind fiberglass. After the pro crew applied closed-cell spray foam, moisture dropped, and the mold stopped. Bills also dipped over several months.
Cost Considerations & ROI Analysis
Upfront Installation Cost Comparison
- Spray foam runs higher per square foot. The exact price varies by region and job size, but it often costs 2–3 times more than fiberglass material plus basic labor.
- Fiberglass batts are cheaper and often bought in big-box stores; blown-in costs more than batts but still less than spray foam labor.
- To get a quote, reach out to experienced spray foam insulation contractors in your area.
Long-Term Energy Savings
- With a better seal, spray foam can reduce energy bills noticeably. In Jackson, MS, some homeowners report savings of $30–$60 per month after spray foam in the attic. Over the years, savings can offset the extra costs.
- Fiberglass plus good air sealing can save money too, but may need more frequent checks for sagging or gaps.
Maintenance and Longevity
- Spray foam stays in place and won’t sag. It can last decades without loss of R-value.
- Fiberglass can settle or shift, especially if exposed to moisture or pests. You might refill or replace loose-fill over time.
Example: A homeowner rechecked attic fiberglass after 10 years and saw settling reducing R-value. They then added more fiberglass and extra sealing.
Health & Environmental Impacts
Indoor Air Quality & Allergens
- Spray foam seals out dust and pollen from leaks, helping allergy sufferers. Once cured, it stays solid.
- Fiberglass fibers can irritate skin or lungs if disturbed. With proper gear, installers minimize risk, but disturbed batts (e.g., during remodeling) can release fibers.
Eco-Friendliness & Green Incentives
- Many spray foam products now use lower global warming-potential blowing agents. A high R-value can cut energy use.
- Government rebates or tax credits may apply when you upgrade insulation or improve home efficiency. Check local and federal programs.
- Fiberglass also can have recycled content, but its lower R-value means you may add more material over time.
Chemical Concerns & Safe Use
- Spray foam involves chemicals that cure on-site. The installer must vent the area during application. After curing, off-gassing is minimal. Hiring pros cut risks.
- Fiberglass is inert once installed, but dust or fibers during installation must be handled with PPE.
Installation Process & Professional vs. DIY
Why Hire Spray Foam Insulation Contractors?
- Proper mix ratio, correct spray thickness, and coverage matter. Pros have gear, training, and know local codes.
- They manage prep, cover vents, protect surfaces, and ensure safe curing. This step influences performance and health.
DIY Fiberglass: Feasibility and Pitfalls
- Many homeowners install batts themselves. It’s straightforward if walls or attic are accessible and you follow safety steps.
- Risk: cutting around pipes or wires can leave gaps. Poor fit means less insulation value and more drafts. Always wear a mask, gloves, and long sleeves.
Prep Work & Timeline
- Spray foam: The crew sets up in a day for a typical attic but may need curing time before re-entering. They seal the attic floor or underside of the roof deck.
- Fiberglass: you roll batts between joists or blow in loose fill over a day or weekend. But add air sealing steps (caulk, foam strips) to limit leaks.
Ready to Secure Comfort and Cut Bills? Let’s Talk!
Feeling ready to make your home more comfortable and lower those energy bills? Our spray foam insulation contractors are here to help. Reach out for a free quote, and we’ll review your space, spot any leaks, and share clear next steps.
With a simple check and a smart plan, you can enjoy a cozier home and see savings over time. Take action today; a quick call or message can set you on the path to better comfort and lower costs. We’re ready when you are!
Your Top Questions on Spray Foam vs. Fiberglass
Is spray foam insulation worth the extra cost compared to fiberglass?
In many cases, yes. A better seal and higher R-value often mean lower bills over time. But if you plan a short stay or have a tight budget, fiberglass plus extra sealing may work.
How long does spray foam insulation last versus fiberglass?
Spray foam can last decades without losing R-value. Fiberglass may settle or shift, sometimes needing topping up after several years.
Can I install spray foam insulation myself?
DIY spray foam is not recommended. Pros have the gear and know how to handle chemicals safely. For fiberglass batts, DIY is common if you follow safety steps.
Does spray foam insulation cause health issues?
Proper venting and curing by pros limit risks. Once cured, the spray foam stays inert. Fiberglass can irritate during installation, so wear protective gear.
What R-value do I need for my climate?
Check local code or Energy.gov recommendations. In hot, humid areas like Mississippi, aim for higher attic R-value and good sealing. Closed-cell foam helps where space is tight.
How does spray foam insulation impact indoor air quality?
It seals out leaks where dust, pollen, or pollutants enter. Ensure proper ventilation when applying, then enjoy fewer drafts and better comfort.