When comparing spray foam insulation and fiberglass insulation for energy savings, spray foam typically delivers better performance due to its higher R-value and superior air-sealing capabilities. It creates an airtight barrier that significantly reduces air leaks, which are a major cause of energy loss in homes. While fiberglass insulation is more affordable upfront, its energy efficiency is generally lower, especially in extreme temperatures or older structures.

This article breaks down the critical differences in energy efficiency, long-term cost implications, and technical specifications of both insulation types. Use this guide to make an informed decision based on measurable data, not marketing claims.

Quick Comparison at a Glance

Feature	Spray Foam Insulation	Fiberglass Insulation
Average R-Value per Inch	6.0–7.0 (closed-cell)	2.2–2.9
Air Sealing	Excellent	Poor
Moisture Resistance	High	Low
Installation Cost (per sq ft)	$1.00–$3.00	$0.40–$1.50
Lifespan	20–30+ years	10–25 years
Energy Savings Potential	High	Moderate
DIY-Friendly	No	Yes

[Image: Attic insulation with spray foam application]
[Image: Worker installing fiberglass batts between ceiling joists]

Energy Performance Overview

 R-Value Efficiency

R-value measures resistance to heat flow—the higher the number, the better the insulation. Spray foam, particularly closed-cell, has a much higher R-value per inch compared to fiberglass.

Material Type	R-Value per Inch	Air Barrier	Water Barrier
Closed-Cell Spray Foam	6.0–7.0	Yes	Yes
Open-Cell Spray Foam	3.5–3.8	Yes	No
Fiberglass Batts	2.2–2.9	No	No
Loose-Fill Fiberglass	2.2–2.7	No	No

Bonus Tip: Closed-cell spray foam not only insulates but also adds structural strength to walls and roofs.

Long-Term Energy Savings

Spray foam provides a more substantial energy-saving advantage over time. According to the U.S. Department of Energy, homeowners can save up to 20% on heating and cooling costs by properly air-sealing their homes—a function fiberglass alone cannot perform.

• Spray Foam: Cuts energy bills by reducing heat transfer and stopping air leaks.
• Fiberglass: Reduces heat loss but does not stop air infiltration.

Bonus Tip: Combine fiberglass with a separate air barrier (like caulk or vapor barrier) to enhance performance.

Technical Specifications

Specification	Spray Foam	Fiberglass
Application Method	Spray-applied	Laid or blown-in
Cure Time	8–24 hours (spray foam)	None
Fire Resistance	Requires fire barrier coat	Naturally non-combustible
Density (Closed-cell)	1.75–2.0 lbs/cu ft	N/A
Sound Absorption	Good (open-cell)	Moderate
Thermal Bridging Protection	Excellent	Poor

 

Things to Consider Before Making a Decision

Home Age and Structure

• Older homes may benefit more from spray foam due to significant air leakage and irregular cavity sizes.
• New builds can optimize costs using fiberglass with air sealing in milder climates.

Budget Constraints

• Fiberglass is cost-effective for upfront investment.
• Spray foam requires a higher initial cost but offers quicker payback through energy savings.

Climate Zone

• Colder and hotter regions benefit most from spray foam due to better thermal resistance.
• Fiberglass performs adequately in moderate climates if installed properly.

Moisture and Mold Resistance

• Spray foam resists moisture intrusion, lowering the risk of mold growth.
• Fiberglass absorbs moisture, reducing effectiveness and increasing potential for mold issues.

Accessibility and Installation

• Spray foam must be installed by professionals.
• Fiberglass is DIY-friendly but can be improperly installed, lowering performance.

Common Questions

How does spray foam reduce energy bills more effectively than fiberglass?
Spray foam prevents air leaks, which are a primary source of energy loss. Fiberglass only slows down heat transfer but allows air to pass through gaps.

Is the higher cost of spray foam worth it long-term?
In many cases, yes. Homes using spray foam often see a 15–20% reduction in annual energy bills, offsetting the upfront cost within 5–7 years.

Can you combine both materials in one home?
Yes. Hybrid systems use spray foam in critical areas (rim joists, attics) and fiberglass in less vulnerable zones to balance cost and performance.

What happens if fiberglass gets wet?
It loses its insulating properties and can develop mold. It must be dried or replaced to regain efficiency.

Does spray foam offer soundproofing benefits?
Open-cell spray foam absorbs sound well, making it ideal for interior walls or between floors.

Spray Foam vs Fiberglass Cost Comparison

Cost Type	Spray Foam (Closed-Cell)	Fiberglass Batts
Material Cost (per sq ft)	$1.00–$2.00	$0.40–$0.90
Installation Labor	High	Low
Average Project Cost (Attic)	$2,000–$6,000	$1,000–$3,000
Maintenance/Replacement	Minimal	Medium (10–15 yrs)

Bonus Tip: Always calculate total lifecycle cost, not just upfront installation expense, when choosing insulation.

Topic FAQ

Which insulation lasts longer—spray foam or fiberglass?
Spray foam typically lasts over 30 years without degrading, while fiberglass may sag or settle over time, reducing performance.

Is spray foam safe for indoor air quality?
Once fully cured, spray foam is inert. Proper ventilation during installation is essential to avoid chemical exposure.

Do insulation R-values degrade over time?
Fiberglass may lose R-value if compressed or dampened. Spray foam maintains its R-value unless physically damaged.

Can insulation be installed over old material?
Yes, but the existing material must be dry, clean, and mold-free. Consult a professional before layering new insulation.

Which insulation is more environmentally friendly?
Fiberglass is made from recycled materials but has lower efficiency. Spray foam offers long-term energy savings but contains chemicals.

Make the Right Decision

Choosing between spray foam and fiberglass depends on your climate, budget, and long-term energy goals. Spray foam offers better performance, energy savings, and durability—ideal for maximizing insulation efficiency. Fiberglass remains a cost-effective option for short-term needs or milder climates.

Evaluate your home’s insulation needs based on location, structure, and financial priorities. For maximum efficiency, consider combining materials strategically.

For more: https://www.hituponviews.com/the-best-social-media-marketing-agency-for-insulation-contractors-in-reading-pa/