Where should you not use spray foam? | ASLONG Guide

Where Should You NOT Use Spray Foam? – A Guide for Sound Insulation Professionals

Spray foam is often considered for soundproofing, but its disadvantages—such as poor acoustical performance and potential damage to certain structures—mean it’s not always suitable. This article addresses the keyword “Where should you not use spray foam?” so professionals can avoid costly mistakes and ensure effective insulation.

Where Should You NOT Use Spray Foam?

Risk Zones for Spray Foam Application

- Historic or Breathable Structures

- Spray foam blocks vapor movement, undermining the breathability of old brick or timber walls.

- May accelerate decay and void the building’s heritage status (Heritage England).

- Areas with Electrical Wiring

- Can overheat and embed electrical cables, contravening NEC recommendations (National Electrical Code).

- Difficult to inspect or maintain wiring, increasing fire risk.

- Damp or Wet Surfaces

- Spray foam fails to adhere properly to moist substrates.

- Traps existing moisture, promoting mold, rot, or structural compromise (U.S. Department of Energy).

- Enclosed Cavities without Adequate Ventilation

- Emits volatile organic compounds (VOCs) during curing.

- Poor ventilation poses a health risk to installers and occupants (EPA).

- Ceilings or Attics with Vermiculite/Asbestos

- Agitation during foam installation may release hazardous fibers.

- Should only be handled by licensed abatement professionals (OSHA guidelines).

Inadequacies for Sound Insulation

- Thin Wall Assemblies

- Open-cell foam provides limited mass and is not effective for blocking mid-low frequency sounds (NRR data, OSHA).

- Partition Walls for Confidential Spaces

- Spray foam’s air seal helps with airborne sound but lacks density for soundproofing compared to mineral wool or acoustic panels.

- Data: Mineral wool achieves up to 45 STC vs. 36–39 STC for open-cell foam in similar wall cavities.

- Floor Cavities between Multi-Unit Dwellings

- Footfall and impact noises are poorly mitigated; recommend mass-loaded vinyl or rigid insulation.

Material Compatibility and Code Issues

- Unvented Metal Roofs

- Risk of trapped moisture leading to corrosion (Metal Construction Association).

- Not recommended unless foam is specifically rated for closed-metal systems.

- Buildings Requiring Easy Retrofit Access

- Hardens to a rigid structure, complicating future retrofits and upgrades.

- Fire-Prone Applications

- Many spray foams are combustible and require additional barriers, per the International Building Code (IBC).

Sustainable and Health Considerations

- Green-Building Certified Projects

- Petroleum-derived spray foam may not meet LEED or BREEAM criteria due to global warming potential and emission of hazardous chemicals.

- Sensitive Occupant Environments

- Avoid in hospitals, schools, or spaces used by chemically sensitive individuals due to off-gassing (EPA).

References

- Heritage England, “Energy Efficiency in Historic Buildings”

- U.S. Department of Energy, “Spray Foam Insulation”

- National Electrical Code (NEC)

- Occupational Safety and Health Administration (OSHA)

- Environmental Protection Agency (EPA)

- Metal Construction Association

- International Building Code (IBC)

Key Takeaways

- Avoid spray foam in buildings where breathability, electrical safety, or future retrofit needs exist.

- Its sound-absorbing qualities are limited compared to industry-preferred solutions like mineral wool or acoustic panels.

- Always verify compatibility with building codes and health guidelines.

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