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Foundations For homeownersFree
Soundproofing with Spray Foam
How open-cell spray foam deadens sound between rooms and from outside — and where it helps most.
3 min 2 modules
Lesson
Open-cell foam fills cavities and air-seals, which cuts airborne sound. For serious isolation, pair it with mass and decoupling — foam alone dampens but doesn't block low frequencies.
Key takeaways
- Open-cell foam fills cavities and air-seals, which stops airborne sound transmission.
- It works best in interior walls, around plumbing, and between floors — not as a standalone sound barrier.
- For serious sound isolation, pair foam with mass (drywall) and decoupling, not foam alone.
Step by step
- 1Identify the sound path — shared wall, floor/ceiling, or exterior.
- 2Spray open-cell in the cavities to air-seal and dampen resonance.
- 3Seal gaps around outlets, plumbing, and duct penetrations.
- 4Add mass (double drywall or sound-rated board) for higher STC needs.
Quick checklist
- All cavities filled with no voids.
- Penetrations (outlets, ducts, pipes) sealed.
- Foam paired with mass where high STC is needed.
- Decoupling considered for serious isolation.
Common mistakes
- Expecting foam alone to soundproof a shared wall — it dampens, but mass does the heavy lifting.
- Using closed-cell where sound dampening is the goal — it's rigid and transmits more than open-cell.
- Leaving gaps around outlets that leak sound.
Ready to put it into practice?
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