Is expanding foam good for sound proofing? | ASLONG Guide

Is Expanding Foam Good for Sound Proofing?

This article explores whether expanding foam is good for sound proofing, answering common questions for industry professionals. Learn about expanding foam’s acoustic properties, performance data, and the most effective materials for professional sound insulation applications.

Expanding Foam and Sound Insulation: Key Considerations

- What Is Expanding Foam?

- Expanding polyurethane foam is widely used for sealing gaps and cracks in construction.

- Known for thermal insulation and reducing air leakage, not specifically designed for sound insulation.

Acoustic Properties of Expanding Foam

- Sound Absorption vs. Sound Blocking

- Expanding foam works as an air sealant but is not effective at mass-based sound blocking.

- NRC (Noise Reduction Coefficient) values are limited for foams compared to dedicated acoustic materials.

*(Ref: Johns Manville (https://www.jm.com/content/dam/jm/global/en/building-insulation/Files/BI_BSI_ExpandingFoam_Datasheet.pdf))*

- Frequency Performance

- Performs better at mid-to-high frequencies due to open cellular structure.

- Low-frequency sound transmission remains largely unaffected.

- STC Ratings

- Expanding foams rated STC 14–20, while standard soundproofing products (rock wool, dense fiberglass) range from STC 30–50+.

- Source: (https://www.usgbc.org/credits/sound-transmission-class-stc)

Practical Applications

- Best Uses

- Effective for sealing penetrations, electrical boxes, and irregular joints to prevent air and flanking paths.

- Useful in combination with heavy soundproofing barriers, not as a primary solution.

- Limitations

- Lacks density to block transmission of impact and airborne noise.

- Not suitable as a standalone product for rooms requiring high-level acoustic isolation.

Alternatives: Superior Sound Insulation Materials

- Mineral Wool / Rock Wool

- High density, strong sound absorption, and better fire resistance.

- Acoustic Batts and Fiberglass

- Effective for both absorption and limiting transmission, suitable for walls, ceilings, and floors.

- Mass Loaded Vinyl (MLV)

- Flexible, dense sheets increase wall mass and dampen sound transfer.

- Acoustic Sealant

- Remains flexible, maintains long-term acoustic performance at joints and seams; does not shrink like foam.

Key Takeaways for Professional Use

- Expanding foam is good for filling gaps to reduce air leaks, not for blocking noise transmission.

- Use as a supplement with denser, mass-loaded insulation for optimal results.

- Rely on STC and NRC ratings when selecting materials for professional soundproofing projects.

- For high-performance environments—studios, offices, healthcare—opt for proven acoustic materials.

Authoritative References

- Acoustic Performance of Building Materials: (https://nrc-publications.canada.ca/eng/view/fulltext/?id=08cde544-c045-4da8-87f8-2649ae2e9ff5)

- Green Building Standards: (https://www.usgbc.org/credits/new-construction/v4/surrounding-quality/sound-transmission-class-stc)

For professional advice or more information about sound insulation materials, consult ASLONG manufacturers and technical specialists.