What to note before you ask anyone
A smell is easier to investigate when it has been described. Spend a few days noticing it, and write down the answers to these:
- When did it start: straight after the foam went in, or weeks or months later?
- Is it stronger in one room, at the top of the stairs or only when the hatch is opened?
- Does it change with the weather, getting worse in damp or humid spells and fading when it is dry?
- Is it musty, sharp, sweet or chemical, in your own words?
- Do other people in the house notice it too, and has anything else changed: new stains, condensation on windows, a damp patch on a ceiling?
Those details are useful to the person you ask next. A smell that arrived the week the foam went in has a different story from one that crept in over a wet winter.
Pinning down the exact cause of a particular smell, and judging any effect on health, are both matters for the manufacturer's information and, if you are worried about symptoms, for your doctor. What a roofer can address is the condition of the roof and the timbers.
Asking the installer first
The company that installed the foam is the first call. They know the product, the date and the conditions it was applied in, and they hold the data sheet. Ask for these in writing:
- the product name, and which of the two foam types is on your rafters
- when it was installed and what the weather was doing
- any guidance supplied about airing or ventilating the property afterwards
- what they say about the smell, and what they propose to do about it
Keep a record of the conversation. Email is better than a phone call, because it gives you a dated reply to refer back to.
If the installer cannot be traced, or has no answer, you can still get the same information from the product's manufacturer, whose details should be on any paperwork from the job. Failing that, a loft survey can often identify the type of foam by looking at it.
If the smell has gone within a short time, nothing more may be needed. If it persists, move to the next step rather than waiting it out for months.
Bringing in a surveyor
A smell that does not fade is a reason for an independent look. Foam hides the roof timbers, and RICS says in its consumer guide that timbers under foam cannot be examined in full. So if the odour might point to damp, the loft is the place to find out.
A survey looks at the outside of the roof first, for tiles or slates that have slipped, for flashings and valleys that could be letting water in. It then moves into the loft to check any exposed timber, the edges of the foam and the underside of the felt wherever it can be reached. Our page on the spray foam survey sets out the whole visit.
The Energy Saving Trust notes that water reaching timbers sealed behind foam can cause rot, so a persistent damp smell is worth treating as information and not as a nuisance. It may turn out to be something harmless, and it is far better to know.
You get photographs of whatever the surveyor finds, and the findings tell you which of an installation question or a roof one you are facing.
When taking the foam off is worth considering
Removal is one option and not the automatic answer. If the installer resolves the smell and the roof survey finds dry, sound timbers, there is no need to take the foam off for that reason alone.
It comes into view when the survey shows damp or rot behind the foam, when a leak has been found that cannot be repaired properly from outside, or when you decide you would rather have a roof you can inspect. Some owners also decide to remove foam because a buyer, lender or insurer has raised questions about it.
The work itself is straightforward to describe. Foam comes off the rafters by cutting and scraping and goes into bags, the felt and timbers are checked and repaired, and the loft is insulated again with ventilation suited to the roof. Spray foam removal sets out the stages, and the page on whether spray foam is bad puts the wider concerns in context.
The survey comes first, so any decision is made with the facts in front of you.
