The short answer
There is no single form that every lender accepts, so ask whoever wants proof exactly what they need. A useful file usually holds the original assessment, photographs of the rafters after the foam has come off, a description of the new insulation and ventilation, any building control paperwork and the written invoice. Ask for these before you book, not after the job.
Why people ask for proof
Once foam has been removed, the next buyer, lender or surveyor needs to know the roof was left in good order. Because RICS accepts that the presence of foam may weigh on a valuation, proof that it has gone can weigh the other way. A sale that stalls over the roof often restarts once a clear paper trail appears.
A report from November 2024 split lenders into those that would not lend on foamed homes and those that looked at each case. A lender in the second group may well ask what was done and by whom. What they ask for is their decision, so request the requirements early rather than guessing and paying for a document nobody wants.
What a good record contains
Think of the file as a story with a before, a during and an after. The before is the assessment, with photographs of the foam and any timber damage that could be seen. The during is a note of what was removed, whether any rafters needed repair, and how the waste was handled. The after is photographs of the cleaned timbers, a description of the new insulation and the ventilation at the eaves, which are the bottom edge of the roof, plus the ridge if an opening was added.
To that, attach the quote, the final bill and the guarantee. Keep it all in one folder, on paper or on a drive, so your solicitor can have it within minutes. Our guide to the spray foam assessment shows how the first part is produced.
Paperwork that depends on the work
If removal is followed by work that counts as notifiable under the Building Regulations, the records from the building control body belong in the file too. The Planning Portal says that renovating a thermal element can bring in further requirements, such as making sure the insulation is sufficient. Where the job is notifiable we handle the Building Regulations notification and explain what consent is involved, so that paperwork reaches your folder instead of being left to chance.
Not every reinsulation job is notifiable, and that is fine. In those cases the file leans on photographs and the description of the work, and the contractor should say plainly why no notification was needed. A short note to that effect, signed and dated, is far better than silence when a conveyancer comes asking years later.
Swindon Borough Council runs its own building control team, and a registered building control approver is the private alternative. Your solicitor can tell you what the buyer's side will expect to see, and our page on spray foam removal and Building Regulations sets out when notification arises.
Who should supply what
The contractor supplies pictures from the survey, the quotation, the bill and the guarantee. You supply the property details and any history of the foam. The lender can say what it wants to see, and the insurer can confirm its terms in a letter. Nobody can supply a document that has not been created, so the time to ask is before work starts, when it costs nothing to take an extra set of pictures.
It also helps to date everything. A photograph with a clear date, a numbered invoice and a quote that matches the work make it easy for a third party to follow what was done. Where pictures are taken, ask for the whole length of the roof, not a single cherry-picked rafter, so a reader can trust the set.
Ventilation, flat roofs and listed buildings
Many of the questions a surveyor raises are about moisture, so a note on ventilation helps. Read whether the roof needs ventilation after spray foam removal to see what should be recorded. If your property has a flat section, spray foam on a flat roof covers why the deck and the membrane above it need their own entry in the file.
Listed buildings are different again, because altering one can require listed building consent, and a roof is no exception. The page on spray foam in listed buildings covers it, and a copy of any consent should sit in the same folder.
Records you can start before the work
Some of the best evidence is cheap to gather today. Photograph the loft hatch, the visible foam and any stains on ceilings, with the date showing on your phone. Write down the name of whoever installed the foam, the year, and anything you remember being told about the type used. If the original invoice or a guarantee card is in a drawer, scan it.
Then keep a log of anything that changes. A smell that appears after heavy rain, a patch that grows, a bedroom that feels damp in the morning: dated notes like these help an assessor focus, and they give a lender a believable picture. None of it replaces an inspection, but all of it makes the inspection quicker and the final file more complete.
If a surveyor has already flagged the foam
A surveyor's comment is often what starts the search for a certificate. Our page on what to do when a surveyor flags spray foam walks through the usual route, which begins with the roof being inspected.
When we survey, we take pictures of your roof and send a quote on paper, so you can see the starting point and what the work will involve. Ask us at that stage which photographs and notes will reach you at the end, so the record meets what your lender or solicitor wants. The spray foam insulation removal page explains how to start.