Is Spray Foam Insulation Toxic?

If you've read conflicting information online about spray foam, you're not alone. Some sources say it’s totally safe, others say it’s dangerous. So what's the truth?

The reality is a bit more nuanced. While spray foam insulation is generally considered safe once fully cured, there are still some legitimate concerns — especially with older installations or homes where ventilation isn't properly managed.

Here’s a clear look at the risks, and what UK homeowners need to understand.

What Is Spray Foam Made From?

Spray foam insulation is created by mixing two liquid chemicals on-site. These typically include:

• Isocyanates (a known respiratory irritant)
• Polyol resin (often containing flame retardants or blowing agents)

When sprayed, these chemicals react and expand to form a solid foam. During this curing phase — which lasts between 8 to 24 hours — the foam releases fumes that should not be inhaled.

Is It Toxic After It Sets?

Once fully cured, spray foam is generally stable. But:

• If it wasn’t mixed properly
• If curing was incomplete
• Or if it breaks down due to moisture or poor ventilation

…then chemical off-gassing may still occur — especially in sealed, non-breathable lofts.

This is why you’ll often see complaints about lingering odours, respiratory irritation, or headaches in forums — particularly in cases where the foam was installed poorly or the space lacks airflow.

Is It a Carcinogen?

Some of the chemicals used in spray foam (especially isocyanates) are linked to occupational risks for installers — including asthma and long-term respiratory conditions.

For homeowners, exposure risk drops significantly after curing, but again, that depends on proper application. If spray foam is flaking, discoloured, or damp, removal might be safer than leaving it sealed inside your roof.

Is Spray Foam Safe in My Loft?

Only if:

• The area is ventilated properly
• The foam is fully cured and intact
• No one is exposed to dust or debris from deterioration

Unfortunately, most older UK lofts weren’t designed with airtight insulation in mind — which is why spray foam often causes more issues than it solves.

What If I’m Concerned?

If you’re unsure what’s in your loft or whether it's safe:

• Don’t disturb it
• Avoid heavy loft use until assessed
• Contact a professional for advice

At Snug & Secure, we offer no-pressure guidance and safe, documented spray foam removal — including breathable re-insulation that meets all UK standards.

Final Thoughts

Spray foam isn’t automatically toxic — but it does come with real chemical risks, especially when applied incorrectly or left in poorly ventilated lofts.

If you're noticing odours, health symptoms, or simply want peace of mind, contact us for straightforward advice — or explore our blog for more no-nonsense guidance.