Foam sprayed under a roof used to be a selling point. Since 2023 it has more often been a line in a surveyor's report, and the line can hold up a sale. A buyer who needs a mortgage depends on a lender being willing to accept the property, and some lenders have not been.
This guide is written for the seller. It sets out the choices open to you, what evidence helps whichever you pick, what it costs on national figures, and where a roofer fits into the process. The buyer's side is covered separately in our guide to buying a house with spray foam insulation, and the whole service sits on the main spray foam insulation removal page. Nothing here is legal advice; your conveyancer decides what you must disclose.
Why foam in the roof slows a sale
A purchaser's lender wants to know that the house is good security for the loan. Spray foam coats the inner face of the slates or tiles, hides the timbers and, if it was fitted badly, can lead to moisture trouble that nobody sees until the damage is done. The Royal Institution of Chartered Surveyors (RICS) published a consumer guide in March 2023 warning of exactly those risks, and advising owners to check with both their mortgage provider and their insurer before foam goes in.
The mortgage market has reacted unevenly. A November 2024 report drawing on a BBC investigation described several lenders refusing homes with foam in the roof, and others weighing each case separately. Our guide to spray foam and equity release deals with one corner of that picture, and the mortgage guide with the rest.
What it means for you
If the buyer's lender declines, the sale does not simply wobble: it can fall through, or the price can be renegotiated downwards. A cash buyer may care less, but their surveyor will still raise it. Each of these outcomes is more likely when you have no paperwork at all and a stranger finds the foam first.
Find out what you actually have
Many sellers did not install the foam themselves. It came with the house, or a previous owner had it done, and the papers are missing. Before you decide anything, get facts, because every later step depends on them, from the asking price to what your buyer's surveyor writes down.
Start with the loft
When the roof void can be reached safely, look at the underside of the slopes. Foam is usually pale yellow, off-white or grey, and has a solid, slightly crumbly surface. Take photographs, and note whether it covers rafters entirely or sits between them. Do not cut into it or lean on it, and keep to the joists, because ceiling plasterboard will not take a person's weight. If the loft has no safe boards or light, a roofer can look instead and send you pictures.
Then get a written assessment
An assessment records the foam type, the extent of coverage, any signs of moisture, how the roof breathes and what the timbers look like where they can be seen. MyBuilder's 2026 guide puts a typical assessment at about £100 to £200 across the UK. The details of what such a report holds are in our guide to spray foam assessments.
For a seller, the report has a second use. It turns an unknown into a documented condition, and a documented condition is easier for a buyer to price than a mystery.
Order the assessment before you instruct an estate agent where you can. It then goes into the sales pack from day one rather than arriving as a bad surprise after the buyer's survey.
Three routes: leave it, evidence it, or remove it
Once you know what is there, there are three realistic ways to go. None is right for every house.
Leave it and disclose it
If the assessment shows dry timbers, sound slates and ventilation that works, you can sell with the foam in place and present the report alongside it. This keeps your costs down but leaves the buyer with the lender question. Expect a narrower pool of purchasers and possibly a price conversation. Agents tend to ask early whether a mortgage buyer can proceed, so have the answer ready, and have the assessment to hand when you do. RICS does not say foam must come out, and nor do we.
Evidence it more fully
Some sellers go a step further and ask for a moisture and ventilation check from a qualified professional, since RICS expects thermal and condensation checks to be done by someone qualified. This gives the buyer's surveyor something to read, not just something to fear. It also gives your own agent a firm answer when a viewer asks what the white or yellow layer under the roof is, and what, if anything, has been done about it.
Remove it before sale
Removal takes the issue off the table, at a price. MyBuilder's 2026 national figures put removal at about £20 to £50 per m², averaging around £1,500 for a job, with disposal around £150 to £400 and repairs plus new insulation between £500 and £3,000. Our guide to spray foam removal costs explains what drives them.
Removal also means re-insulating, so plan for the loft being left in a fit state, not simply bare. A roof stripped of foam and then re-insulated can be described honestly to a buyer; one left half-done raises more questions than it answers.
Timing removal against your sale
The calendar matters more than people expect. A removal needs the roof void cleared, the foam taken off by hand, the timbers checked, and the loft made good. It is not a job to squeeze into the week before exchange.
If you have not yet listed
This is the easiest case. Complete the work, collect the paperwork and list with the evidence in hand. Viewers then see a house with a settled roof history, and the survey has little to find.
If you are under offer
Tell your conveyancer at once. Depending on the lender's attitude, the buyer may want the foam removed before completion, a retention from the price, or a reduction. A written quote for removal gives everyone a number to work with instead of a guess.
Weather and access
Plenty of Stroud valley houses stand up a steep lane or on a terraced slope. We look at where the scaffold can go and how materials arrive during the survey, and that goes into the figures before you see them. Our answer on how long removal takes sets out the duration, and the winter answer covers cold-season issues.
Should the roof need repairs once the foam is off, you will want to hear about it before completion, not afterwards. That is a good reason to arrange the inspection of the timbers at the start, not the end.
Evidence that helps a buyer say yes
Buyers and their advisers trust documents more than reassurance. A good file for a house with foam, or one that has had it removed, might include the following.
- The assessment report. It identifies the foam and the condition of what lies beneath.
- Dated photographs. Pictures of the roof void before work, during it and after, taken from your own roof. We take these at survey and again when the job ends.
- Any original paperwork. A guarantee, a survey or a letter from whoever installed the foam, even if it is old.
- The invoice for removal and re-insulation. A bill that records scaffold, stripping, labour, waste and making good reads clearly to a stranger.
- Certificates where the work was notifiable. Where building control was involved, keep the completion paperwork. Our answer on spray foam removal and building control explains when that arises.
A word on guarantees
Our own work carries a written guarantee on workmanship for ten years. A buyer or lender may ask for more than that, such as a surveyor's confirmation, and we can supply the photographs and the invoice to support one.
What you must say, and what your conveyancer will ask
This is the part where we step back. What a seller has to disclose, and how, is for your conveyancer to explain, and we are not in a position to advise on it. Here is the practical side.
Your conveyancer will send you forms that ask about the property, including work done to it and any guarantees. If you know there is spray foam in the roof, the sensible and straightforward approach is to say so and to hand over the assessment or any photographs you hold. A buyer who learns about the foam later may feel misled even where no rule was broken, and that feeling costs sales.
If you do not know
Sellers who really do not know should say so, and consider arranging the assessment to find out. Guessing in either direction is worse than saying you have not checked.
Insurance and mortgage on your side
Check what your own insurer and lender understood about the foam. RICS tells owners to confirm that their policies allow it. If you have a mortgage with the same lender as your buyer, ask them directly what they would require. A short email to a lender can save weeks in the sale. Ask what documents they would want to see, and in what form, so that you gather the right ones once instead of three times.
If your conveyancer needs a roofer's note on the condition of the roof void, we can write down what we found at survey in plain terms, with the photographs, for you to pass on.
Talking to us about a sale
We are roofers, and our part in a sale is the roof. We survey, photograph and report on what is there. If removal is the choice you make, the quote we write after the survey covers scaffold, removal, disposal, any timber repair, re-insulation and making good, so your buyer's advisers can read exactly what was done.
On VAT, the re-insulation part of a home loft job is zero-rated through to 31 March 2027, but removal and repair work normally carries the standard rate, so the totals differ by line.
Materials go back like for like, and we leave the site tidy with the waste taken away. Our number is 01453 933613, and WhatsApp and the enquiry form both reach us too. If a sale has a date attached, tell us when you start, because the sequence of survey, quote, work and paperwork has to fit around your conveyancer.