Can Spray Foam Rot Your Roof?
Spray foam insulation has been marketed as a modern solution to heat loss and rising energy bills — especially in older UK homes. But many homeowners are now discovering the hidden problems that come with it. One of the most serious? Timber rot.
At Countrywide Roofing and Insulation, we regularly inspect properties where spray foam has done more harm than good. If you're wondering whether spray foam can cause your roof to rot, the answer is yes — and here's what you need to know.
How Spray Foam Traps Moisture
Roof timbers need ventilation to stay dry and healthy. Even in well-built homes, small amounts of moisture naturally enter loft spaces. Normally, airflow takes care of that. But once spray foam insulation is added — especially closed cell spray foam — the moisture can't escape.
Closed cell foam forms a hard, airtight seal. If any water gets into the roof space, it becomes trapped. Over time, this can soak into the timber and lead to rot. The danger is made worse by the fact that this damage is often hidden behind the foam.
Even open cell spray foam, which is more breathable, can absorb moisture and mask signs of early decay.
📊 Stat: Around 1 in 4 homes with spray foam insulation develop moisture or timber-related issues within five years of installation.
Why You Might Not Notice Until It's Too Late
One of the biggest dangers with spray foam is how well it hides problems. Because it's sprayed directly onto the rafters and felt, any signs of rot, mould, or water damage are covered up.
We've removed foam from lofts where homeowners had no idea there was a problem — until parts of the timber structure had already started to break down. In many cases, the only warning signs are a faint damp smell or soft spots in the ceiling.
Lenders and Surveyors Are Flagging It
Spray foam isn't illegal in the UK, but it is now a major red flag for mortgage lenders and surveyors. Most won't approve a mortgage — or will heavily condition it — if the loft has spray foam insulation. The reason? They can't assess the condition of the timber underneath.
If you're planning to sell your home, refinance, or apply for equity release, spray foam can delay or even block the process until it's removed and the roof structure has been inspected.
📊 Stat: More than 70% of UK lenders now restrict lending on homes with spray foam insulation in the loft.
Open Cell vs Closed Cell: What's the Difference?
Understanding the type of spray foam in your loft is key to knowing the risks:
Open Cell Spray Foam
Light, soft, and slightly breathable
Absorbs moisture like a sponge
Easier to remove
Still problematic for surveys and valuations
Closed Cell Spray Foam
Hard, dense, and rigid
Creates a full vapour barrier — traps moisture
Strong bond to roof timbers and felt
More likely to cause rot and structural damage
More difficult to remove
We offer safe, professional open cell spray foam removal and closed cell spray foam removal throughout the UK. Our team carefully removes the foam and restores the breathability of your loft, helping protect your home from long-term damage.
Like Wrapping Timber in Cling Film
Think of your roof beams like skin — they need to breathe. Now imagine wrapping that skin in cling film. You might stay warm, but eventually, you'll start to sweat. That trapped moisture leads to discomfort and damage. It's the same with spray foam. It seals everything in — and that's where the trouble starts.
What to Do If You Suspect Roof Rot
If you've already had spray foam installed and are worried about the effects, don't ignore it. Here's what you should do:
1. Book a Professional Survey
We'll inspect the type of foam and assess your loft for any signs of damage — even those not visible to the eye.
2. Request a Spray Foam Removal Quote
We'll provide a free, no-obligation quote tailored to your home and the specific type of insulation.
3. Restore Breathability and Protection
After safe removal, we can help improve loft ventilation and insulation, making your home healthier, mortgage-ready, and rot-free.
FAQs: Spray Foam and Roof Ro
Can spray foam cause timber to rot?
Yes. Especially closed cell spray foam, which traps moisture against the wood. Without airflow, rot can develop unseen beneath the insulation.Does spray foam need to be removed?
If you're planning to sell, remortgage, or have signs of moisture or damage — then yes. Most lenders now expect it to be removed.
How can I tell if I have closed cell or open cell foam?
Open cell foam is soft and spongey to the touch. Closed cell is hard and rigid. We can inspect your loft and identify which one you have.
Is it expensive to remove spray foam?
Costs depend on the size of your loft and the type of foam. We offer competitive pricing and free surveys to give you clarity.
Can spray foam removal damage my roof?
Not when done professionally. Our team uses specialist tools to remove the foam carefully, avoiding damage to your rafters or roof felt.
Final Thoughts
At Countrywide Roofing and Insulation, we help property owners remove spray foam safely and restore their roof to a healthier, more breathable condition. Whether it's open cell or closed cell spray foam, we've got the tools, experience, and expertise to put things right.
Worried spray foam might be damaging your roof?
Contact Countrywide Roofing and Insulation today for a free, no-obligation quote and expert advice on removal.
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