What paperwork should I get for spray foam insulation?

Four documents matter. Citizens Advice lists them as: a report from a survey done before any work started, a product certificate showing what type of spray foam was used, a guarantee from the trader who carried out the work, and a guarantee from the manufacturer of the insulation². They belong together, kept after the work is finished, and kept with the deeds rather than in a loft folder that gets lost in a house move.

The paperwork to demand and keep

The full set is straightforward, and Citizens Advice in Wales sets it out plainly: "This should include: a report from a survey that was done before any work started; product certificate showing what type of spray foam was used; guarantee from the trader who carried out the work; guarantee from the manufacturer of the insulation"⁷. Each document answers a different question later on. The survey report shows the state of the property before anyone touched it, which matters if damp or timber problems appear afterwards. The product certificate identifies the material, which matters to mortgage lenders and to anyone assessing moisture or fire risk. The two guarantees say who pays if something goes wrong.

The reason for keeping all four is that spray foam is hard to reverse. It is difficult to remove from floor joists, wires and pipework, so it can present a problem when maintenance work is needed in the future⁸. Removal is sometimes forced by damp and condensation, damage to the property, or the need for a repair such as a roof repair². A household that can prove what was installed, when and by whom is in a far stronger position than one relying on memory.

The pre-work survey report

The survey report comes first because it is the only record of the property's condition before the foam went in. Which? describes what a proper pre-installation survey involves: a U-value calculation showing how well-insulated your home is, an assessment of the risk of condensation occurring, and identifying any problems and measures needed to prevent them⁹. The same principle applies across insulation types: the property must be surveyed thoroughly before any material is installed¹⁰, and for some floor systems you may be required to pay for a survey in advance to establish whether your floor is suitable⁴.

A survey report that shows a condensation risk assessment is worth particular weight. Condensation inside a roof or floor structure is the mechanism by which spray foam can lead to timber problems, and a survey that identified and addressed the risk before installation is the document a surveyor or lender will look for. If the report is thin, a page of measurements with no risk assessment, that is a weakness in the record even if the installation itself was sound.

The product certificate

The product certificate records which spray foam was actually used. This matters because spray foam comes in two forms, open cell and closed cell³, and both are usually made from polyurethane filled with bubbles of gas or air⁹. The two types behave differently in a roof, and a lender or surveyor assessing a property cannot tell them apart by looking at the finished surface. The certificate is the only document that names the material.

The type also matters for risk. Government-commissioned fire testing of retrofitted spray applied closed and open-cell polymeric insulation to the underside of roofs found that such sprayed configurations can satisfy the highest demands for roof covering classification in current guidance¹¹. That finding applies to a specific configuration, not to spray foam in general, which is exactly why the certificate identifying the product matters: the evidence is attached to the material, and only the paperwork connects your roof to it.

The trader's guarantee and the insurance-backed guarantee

There are two guarantee documents to check, and they are not the same thing. The first is the guarantee from the trader who carried out the work. The second is the guarantee from the manufacturer of the insulation⁷. A trader's guarantee is only as strong as the trader: if the firm has ceased trading, the paper may be worthless. That is why professional insulation installation is expected to come with an insurance-backed guarantee as well as public liability and employer's liability insurance, alongside TrustMark registration and membership of a trade assurance body such as the Installation Assurance Authority, the Cavity Insulation Guarantee Agency or the Solid Wall Insulation Guarantee Agency¹².

An insurance-backed guarantee is underwritten separately from the installer, so it survives the installer. Where a scheme such as ECO4 Flex is involved, the grant rules tell recipients to check whether guarantees or warranties are offered and make sure these documents are received after the installation¹³. Signatures on scheme evidence can be digital or wet signatures¹⁴, so an emailed PDF guarantee is as valid as a posted original, provided it is kept.

TrustMark registration and ECO-funded work

For grant-funded insulation, the installer's registration is not optional. Installers under ECO must be TrustMark accredited and will have a registration number, except in the case of installers of district heating connections¹⁵. ECO4 delivery guidance goes further: measures should be installed by or under the responsibility of a TrustMark registered installer and have a relevant certificate of lodgement¹. In Scotland, Home Energy Scotland grant and loan funding requires a TrustMark registered installer for solid wall, underfloor, flat roof or room-in-roof insulation¹⁶, and the same requirement applies to the Private Rented Sector Landlord Loan¹⁷.

TrustMark is a government endorsed quality scheme¹⁸, and its role is that of a competent person register for finding an installer who will assess your circumstances and property to identify suitable measures¹⁹. The practical value to a householder is the lodgement: when work is registered with TrustMark, there is a central record of what was done, which is the backstop if your own copies are lost. The installer's TrustMark registration number can be requested before work starts and checked against the register.

Listed buildings: consent comes before any paperwork

No amount of certificates and guarantees cures a missing consent. Listed building consent must be obtained before installing spray foam insulation anywhere in a listed property, and this is unlikely to be granted⁶. The planning position is consistent across local authorities: introducing new materials to the property, such as insulation, requires listed building consent²⁰, more disruptive work like internal or external insulation will usually need it²¹, and listed buildings require consent for any significant work²².

If spray foam has already been installed in a listed building without consent, the paperwork problem is different in kind: the installation itself may be unauthorised, and no survey report or product certificate will change that. For a listed home, the sequence is consent first, then survey, then installation, then certificates. See insulating and glazing a listed building for the wider rules.

When the paperwork is missing

If the documents cannot be found, the first call is TrustMark on 0333 555 1234²³. Where the installer was registered, the lodgement record may fill the gap, and from August 2026 onwards, appropriate information from corresponding TrustMark lodgements may be used to complete incomplete linked grant recipient records²⁴. Where the work was done under ECO4 or GBIS and quality problems are suspected, the UK Government began offering affected homes free audits in October 2025, with TrustMark conducting the audits and arranging repairs where problems are identified²⁵.

The free audit involves a surveyor carrying out a thorough inspection of the work completed at your property⁵, and it is booked by calling 0333 555 1234 and choosing Option 1⁵. For wall insulation installed inside and outside your home, TrustMark also runs a free home check in which a qualified professional looks at the insulation to see if it was installed correctly²⁶. When TrustMark writes to arrange a visit, the letter quotes your unique measure reference number so you know it is genuine, and a visitor can be asked for their ID and that number to check they are genuine²⁶. The same number check applies to letters about insulation work, as covered in how to know if an Ofgem letter about insulation is genuine.

For the wider background on spray foam and its risks, see spray foam insulation: risks, mortgages and removal, and for the scheme failures that led to the free audits, see the ECO4 and GBIS insulation failures.