Underpinning and Subsidence Repairs: Records Homeowners Must Keep

Subsidence is one of the most thoroughly scrutinised issues in UK residential property. If a house experiences ground movement and undergoes structural remediation—such as traditional mass concrete underpinning, mini-piling, or ground resin injection—the physical work is only half the process. The administrative trail generated before, during, and after the project is essential for securing future buildings insurance, satisfying mortgage lenders, and reassuring future buyers.

The Diagnostic Stage: Investigation and Monitoring Records

Remedial structural work is rarely undertaken without an extensive period of investigation. The documents produced during this investigative phase establish the root cause of the movement and prove that the chosen remedy directly addressed the underlying mechanism. Homeowners should retain all diagnostic reports commissioned by structural engineers, loss adjusters, or specialist contractors.

These diagnostic records typically include geotechnical soil reports detailing soil classification and moisture content, arboricultural assessments identifying tree root interaction with shrinkable clay subsoils, and CCTV drainage surveys checking for cracked or displaced pipework that may have washed away foundation fines. If tell-tale crack monitoring gauges or precision level distortion surveys were installed over a six-to-twelve-month period, the logged readings showing the stabilisation or progressive movement of the structure must also be retained.

Design Calculations and Building Regulations Approvals

Underpinning a foundation is structural work and falls directly under the remit of the Building Regulations in England and Wales. A formal Building Regulations application must be deposited before work commences. A homeowner cannot rely on informal assurances; full regulatory oversight is mandatory.

You should receive and keep the structural engineer's detailed design drawings and structural calculations. These demonstrate the depths of the new mass concrete bays, the load transfer mechanisms, the specification of reinforcement steel, or the layout of engineered piles and needle beams. Once the works are inspected and approved on-site at key stages by the Local Authority Building Control surveyor or a Registered Building Control Approver, a final Building Regulations Completion Certificate must be issued. Retaining this certificate is critical, as absence of statutory sign-off will halt future conveyancing.

The Certificate of Structural Adequacy and Contractor Guarantees

Where remedial works are completed as part of an insurance claim, the appointed consulting engineer or loss adjuster will issue a Certificate of Structural Adequacy (CSA). This document is central to the property's paperwork. It states the address, describes the cause of damage, lists the repair schedule completed, and certifies that the property is structurally stable and suitable for standard insurance terms.

• Geotechnical site investigations, soil testing logs, and arboricultural tree reports.
• CCTV drainage inspection reports and proof of any associated drain repairs.
• Precision crack monitoring records and movement graphs spanning the diagnostic period.
• Structural engineering drawings, calculations, and underpinning bay layout diagrams.
• Building Regulations Approval Notice and the final Building Control Completion Certificate.
• The formal Certificate of Structural Adequacy (CSA) issued upon project completion.
• Contractor guarantees, product warranties, or scheme insurance backed warranties (such as ASUC warranties).

Insurance Correspondence and Future Conveyancing

Standard property transfer forms—such as the Law Society Property Information Form (TA6)—contain direct questions asking whether the building has ever suffered from subsidence, heave, or landslip, and whether underpinning has taken place. Answering 'yes' without full supporting documentation can delay transactions or cause mortgage offers to be withdrawn.

In addition to technical files, homeowners should keep all written correspondence from their building insurer. This includes the formal claim closure letter, details of any policy excess applied, and written confirmation regarding the ongoing terms of cover. Retaining evidence that an insurer has continued to provide cover on standard terms after completion gives prospective buyers and their lenders the assurance they require.

Because subsidence repairs can take place decades before a home is eventually sold, physical paper files are easily lost, damaged, or misfiled across successive owners. Consolidating structural calculations, engineer certifications, and statutory approvals in an independent digital record like Project Passport ensures that vital technical history remains preserved and retrievable whenever proof of structural adequacy is needed.