Spray Foam “Non-Toxic”?


Spray foam insulation gets sold like it’s the final boss of home performance: seal everything, crank the R-value, live happily ever after.

But here’s what doesn’t make it into the sales pitch:

Spray foam is made from reactive chemicals that can seriously harm people during application and when something goes wrong. And yes—there have been waves of lawsuits from homeowners alleging the foam made their homes unlivable.

This isn’t “anti-innovation.” This is pro-truth.

The part contractors gloss over: spray foam is a chemistry experiment in your house

Most spray polyurethane foam (SPF) is a two-part system mixed at the spray gun: “Side A” and “Side B.” The U.S. Consumer Product Safety Commission (CPSC) summarizes it plainly: Side A contains isocyanates, and Side B contains a mixture that can include polyols, amine catalysts, flame retardants, blowing agents, and surfactants. U.S. Consumer Product Safety Commission

If that mix is off, if the temperature/humidity is wrong, if ventilation is poor, if the installer is rushing, if the substrate isn’t right—you don’t get “miracle insulation.” You get a problem trapped inside your building envelope.

“Toxicity” isn’t a vibe. It’s documented occupational hazard.

Multiple public agencies warn about the chemicals involved—especially isocyanates:

  • NIOSH (CDC) notes that exposure to key SPF ingredients (including isocyanates and other SPF chemicals in vapor/aerosol/dust form) can cause asthma, sensitization, lung damage, and irritation. CDC

  • OSHA states that the main effects of hazardous isocyanate exposure include occupational asthma and other lung problems, plus irritation; it also notes some isocyanates are classified as potential carcinogens / known to cause cancer in animals. OSHA

  • CPSC warns consumers may be exposed to chemicals released during and after application and provides safety recommendations for homeowners. U.S. Consumer Product Safety Commission

  • EPA (archived guidance) notes potential exposures can occur even later—during renovations or “hot work” near polyurethane foam—and also says the potential for off-gassing of volatile chemicals is not fully understood and needs more research. US EPA

Translation: the risk conversation is real, and it’s not coming from random internet hysteria—it’s in official safety communication.

Why some homes go sideways after spray foam

When SPF is done perfectly, allowed to cure fully, and the job is managed like a true chemical install (PPE, ventilation, controlled conditions), risks drop substantially.

But the failure modes are ugly:

  • Off-ratio / improper mixing → lingering odor, tacky foam, ongoing chemical emissions complaints

  • Bad ventilation during cure → occupants breathing stuff they shouldn’t

  • Spraying onto damp/dirty surfaces → adhesion problems, long-term performance issues

  • Encapsulating problems → moisture/rot can be hidden and worsen behind “sealed” assemblies

And here’s the kicker: when SPF fails, the “fix” people end up facing is often removal, which is invasive and expensive.

Yes, there have been “numerous lawsuits”—and the paper trail is public

This is the part people don’t hear about until they’re already in trouble.

There have been many homeowner claims alleging injuries/damages tied to SPF insulation products installed in properties. The U.S. Judicial Panel on Multidistrict Litigation described actions involving “injuries and damages allegedly caused by various spray polyurethane foam (‘SPF’) insulation products installed in plaintiffs’ properties.” jpml.uscourts.gov

And reporting has noted lawsuits in multiple states and a surge of complaints around that time period. GreenBuildingAdvisor+1

Important nuance (because we’re being real):

  • Lawsuits ≠ automatic proof of wrongdoing in every case.

  • SPF problems can involve product, installer, jobsite conditions, or all of the above.

But the existence of repeated litigation and official safety warnings should kill the idea that spray foam is automatically “non-toxic” or “risk-free.”

The “buried” part: what homeowners typically learn after the install

A lot of homeowners only discover the hard truths after they smell something off or feel symptoms. And then they’re chasing:

  • what exactly was sprayed,

  • what went wrong,

  • whether the foam cured,

  • what air testing actually means,

  • and what “safe” re-occupancy even looks like.

Meanwhile, the marketing stays simple: “It’s inert after it cures.”
Sometimes that’s true. Sometimes the job was never in a condition to cure correctly.

Even EPA’s own consumer-facing guidance admits uncertainties remain about off-gassing and exposures. US EPA

So what should a homeowner do?

If you’re considering spray foam, treat it like what it is: a chemical application inside your home.

Minimum baseline questions to demand answers to:

  1. What exact product system is being used (brand + SDS)?

  2. What are the re-occupancy instructions from the manufacturer (hours/days)?

  3. What ventilation strategy will be used during and after spraying?

  4. Will the installer document temperature, humidity, substrate moisture, and mix settings?

  5. If something goes wrong: who pays for removal/remediation?

And if you want “high performance” without turning your house into a chemistry project, there are other approaches (air sealing + safer insulation strategies) that can get you most of the benefit with far less downside—especially in a humidity-chaos climate.

The bottom line

Spray foam can be effective.
But pretending it’s “non-toxic” by default is misinformation.

Public agencies warn about its key chemicals and exposure risks. US EPA+3CDC+3U.S. Consumer Product Safety Commission+3
And the litigation history shows plenty of homeowners have alleged serious problems after installation. jpml.uscourts.gov+2GreenBuildingAdvisor+2

If a product demands perfect chemistry and perfect conditions, it’s not “foolproof.” It’s fragile.

And fragile systems don’t belong in people’s homes unless everyone is being fully honest about the risks.

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