Spray Foam vs Batt Insulation
**Fiberglass batts** are cheap and DIY-friendly but need careful installation to avoid gaps. **Spray foam** air-seals and insulates in one step—closed-cell adds structure but costs more and requires pro install.
Step by step
1. Target R-value
Match climate zone code minimums for walls and attic.
2. Air sealing first
Batts need caulk and foam gaps; spray foam seals inherently.
3. Moisture strategy
Closed-cell in bands can trap moisture if assembly is wrong.
Spray foam vs batt
Hybrid approaches—flash-and-batt—balance cost and sealing.
- Batt: Low $/sq ft; labor-sensitive; common in retrofits.
- Spray foam: Higher cost; excellent seal; pro application required.
Use our calculators
Common mistakes
- Compressed batts
- Open-cell in below-grade damp spaces
FAQ
Does spray foam pay back?
Payback depends on energy prices and how leaky the house was.