The short answer
To sell an underpinned house smoothly you need a clear documentation pack: the Certificate of Structural Adequacy, the building-control completion certificate, any contractor guarantees or warranties, the structural engineer's reports, and the insurance and claims history — plus a truthful TA6 Property Information Form disclosing the underpinning. These documents prove the work was designed and approved correctly, that the property was confirmed stable, and that it has remained insurable. They are exactly what the buyer's solicitor, surveyor, lender and insurer will ask for, so assembling them before you list prevents delays. Missing paperwork is the most common reason an underpinned sale stalls, while a complete pack reassures buyers and helps protect the price.
An underpinned sale lives or dies on its paperwork. The sections below list each document, explain what it proves, and show how to fill any gaps before they cost you a buyer.
The core pack
- Proves it workedCertificate of Structural Adequacy
- Proves it's legalBuilding-control completion certificate
- Proves it's backedContractor guarantee / warranty
- Proves it's insurableInsurance & claims history
- Discloses itTA6 Property Information Form
The documents and what each proves
- Certificate of Structural Adequacy: issued by the structural engineer on completion, this is the headline document. It confirms the underpinning was designed and carried out to remedy the movement and that the structure is now adequate.
- Building-control completion certificate: shows the underpinning was inspected and approved under the Building Regulations — essential proof the work was lawful and signed off.
- Contractor guarantees / warranties: any insurance-backed guarantee for the work, ideally transferable to the buyer, covering defects for a set period.
- Structural engineer's reports and monitoring records: the investigation and any post-works monitoring that confirmed the property had stabilised.
- Insurance and claims history: evidence of how the original subsidence claim was handled and that buildings cover has continued — vital for the buyer's lender and insurer.
- TA6 Property Information Form: the standard conveyancing form on which you formally disclose the underpinning and movement history.
Who asks for what
Each professional in the chain wants a particular subset of the pack, which is why having it complete saves repeated back-and-forth:
| Document | Primarily reassures | Why |
|---|---|---|
| Certificate of Structural Adequacy | Surveyor, lender, buyer | Confirms the fix was adequate |
| Building-control certificate | Solicitor, lender | Confirms legal sign-off |
| Guarantees / warranties | Buyer, lender | Cover for future defects |
| Insurance / claims history | Insurer, lender | Property stays insurable |
| TA6 form | Buyer's solicitor | Formal disclosure |
Indicative mapping of documents to the parties that rely on them in an underpinned sale.
Organising the pack for a smooth sale
Beyond simply holding the documents, presenting them well speeds the transaction. A few practical steps:
- Make a single digital folder with clear filenames, so your conveyancer can forward everything to the buyer's solicitor in one go rather than piecemeal.
- Include a short covering note summarising the history: when the movement was found, the diagnosed cause, what work was done, who carried it out, and the fact the property has been stable since.
- Confirm guarantees are transferable and note any steps needed to assign them to the buyer.
- Check the insurance position early, so you can tell the buyer whether the existing policy can transfer to them.
- Keep the originals safe and provide copies, retaining the originals until completion.
A buyer's solicitor who receives a complete, well-ordered pack raises fewer enquiries and is far less likely to cause delay. The contrast with a drip-fed, incomplete set of documents — which invites repeated questions and erodes buyer confidence — is stark, and it is entirely within your control as the seller.
How to fill gaps before you list
If you are missing documents, act before marketing rather than scrambling mid-sale. For a lost Certificate of Structural Adequacy, contact the structural engineering firm that issued it — they may hold a copy on file, or you can ask the original contractor or your insurer, who often retains claim records. Building-control records can usually be obtained from the local authority building-control department or an approved inspector. Guarantee details may be traceable through the contractor or the guarantee provider's register. If the work was old and some paperwork is genuinely unavailable, a fresh inspection and report from a chartered structural engineer confirming the property is currently stable can substitute for, or supplement, the missing history. Whatever you do, complete the TA6 honestly: disclosure is a legal duty, and a buyer reassured by a full pack is far less likely to renegotiate or withdraw than one who uncovers underpinning with no documents behind it.
Frequently asked questions
What is a Certificate of Structural Adequacy?
It is a document issued by a structural engineer once underpinning or remedial works are complete, confirming the work was designed and carried out to remedy the movement and that the structure is now adequate. It is the single most important document when selling or insuring an underpinned property, so keep it safe and provide it to buyers.
What if I've lost the underpinning documents?
Try the original structural engineer, contractor, your insurer (who may hold claim records) and the local authority building-control department for copies. If some paperwork is genuinely unavailable, a current structural engineer's inspection and report confirming the property is stable can help reassure buyers, lenders and insurers in its place.
Do I have to give the buyer all these documents?
You must answer the TA6 truthfully and provide the documents the buyer's solicitor reasonably requests. Supplying the full pack proactively is in your interest — it speeds the sale, supports the price, and reduces the risk of a buyer withdrawing or claiming misrepresentation after completion.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific property. They are guidance, not a quotation.