02/21/2026
When deciding between spray foam insulation and traditional batt fiberglass insulation, the differences go far beyond just R-value. Spray foam offers performance advantages that can significantly impact comfort, durability, and long-term energy costs.
Here’s why many homeowners choose spray foam over fiberglass batts:
1. Superior Air Sealing
Spray foam expands after application, filling cracks, gaps, and hard-to-reach spaces. This creates a continuous air barrier, reducing drafts and preventing uncontrolled air leakage.
Fiberglass batts, on the other hand, do not stop air movement. Air can pass through or around them, reducing real-world performance.
Why this matters:
Lower heating and cooling costs
Fewer cold/hot spots
Less strain on HVAC systems
2. Higher Energy Efficiency
While fiberglass typically provides R-3 to R-3.7 per inch, spray foam provides:
Open-cell spray foam: ~R-3.5 to R-4 per inch
Closed-cell spray foam: ~R-6 to R-7 per inch
Closed-cell spray foam delivers nearly double the insulating power per inch, making it ideal for tight wall cavities or roof assemblies.
3. Moisture and Mold Resistance
Closed-cell spray foam acts as both:
An air barrier
A moisture barrier
This helps prevent:
Condensation inside walls
Mold growth
Wood rot
Fiberglass can absorb moisture. Once wet, it loses effectiveness and may promote mold growth in surrounding materials.
4. Structural Strength (Closed-Cell Only)
Closed-cell spray foam hardens after curing and can increase wall and roof structural rigidity, especially in high-wind areas.
Fiberglass provides no structural reinforcement.
5. Long-Term Performance
Spray foam:
Does not sag
Does not settle
Maintains performance for decades
Fiberglass batts can:
Shift
Compress
Leave gaps over time
6. Indoor Air Quality Benefits
Because spray foam seals air leaks, it reduces:
Dust infiltration
Outdoor pollutants
Pollen and allergens
Fiberglass allows more air movement, which can carry contaminants into the home.
While spray foam costs more initially, many homeowners recover the investment through lower utility bills and fewer moisture-related repairs.
When Fiberglass Might Make Sense
Fiberglass can still be appropriate when:
Budget is tight
The home already has good air sealing
It's used in combination with air barriers and v***r barriers
Bottom Line
Spray foam insulation offers:
Better energy efficiency
Superior air sealing
Moisture protection
Greater durability
For homeowners focused on long-term performance, comfort, and energy savings, spray foam is often the better investment. Message us with your insulation needs either spray foam or fiberglass insulation