Direct answer
Closed-cell foam at 2"+ thickness IS a vapor barrier. No additional barrier needed. Open-cell foam is vapor-permeable; in cold climates, a separate vapor retarder may be required. Partner-network installers design per IECC code.
Authoritative sources
- US Department of Energy ↗
DOE Energy Saver guide to insulation types, R-values, and recommended applications.
- IRS Section 25C ↗
Energy Efficient Home Improvement Credit, up to $1,200/yr for qualifying insulation work.
- Energy Star ↗
Energy Star recommendations for attic and wall insulation R-values by climate zone.
Related questions
- How much does spray foam insulation cost in Cincinnati? →
- Should I use closed-cell or open-cell spray foam? →
- How does spray foam compare to fiberglass and cellulose? →
- Are there tax credits for spray foam in 2026? →
- How long does spray foam insulation last? →
- How much will I save on heating and cooling? →
- How long does spray foam installation take? →
- Can I be home during the install? →
- Should I foam the roof deck or the attic floor? →
Ready to get started in Cincinnati?
We connect Greater Cincinnati homeowners with BPI-credentialed spray foam installers in our partner network. Mon-Fri 7am-6pm · Sat 9am-3pm.