Subsidence — the downward movement of ground beneath a building — affects thousands of UK properties. It can cause cracking, structural damage, and significant reduction in value. But many properties with historic subsidence have been successfully repaired and are perfectly mortgageable.\n\nWhat Causes Subsidence — Clay soil shrinkage (the most common cause, affecting properties in London, the South East, and East Anglia during dry periods). Tree root activity drawing moisture from clay soil. Historical mining activity. Water course erosion. Poorly compacted fill material beneath foundations. Leaking drains washing away subsoil.\n\nHow Lenders Assess Subsidence — Lenders rely on the surveyor's assessment. The valuer will look for cracking patterns (diagonal cracks wider than 5mm are particularly concerning), signs of historic movement, evidence of monitoring or remediation, and whether the property has been underpinned. The key factors are whether the subsidence is ongoing or historic, whether it has been properly investigated and remediated, and whether the property is insured.\n\nUnderpinning — This is the main structural remedy for subsidence. It involves strengthening the foundations by extending them to a deeper, more stable layer of ground. Traditional mass concrete underpinning is the most common method. Mini-piling and resin injection are modern alternatives. A property that has been professionally underpinned with appropriate engineering sign-off is generally mortgageable. The certificate of structural adequacy (from a chartered structural engineer) is the document lenders need to see.\n\nLender Attitudes — Halifax and Nationwide are generally pragmatic about underpinned properties, provided there is an engineer's certificate and the property is insured. Some lenders restrict LTV to 75% or lower. A small number of lenders decline underpinned properties outright. Building societies with manual underwriting (Leeds, Bath, Furness) often take a common-sense approach. A whole-of-market broker experienced in non-standard properties is essential.\n\nInsurance — Buildings insurance for a previously subsiding property costs more than standard cover. Premiums may include a higher excess for subsidence claims (typically 1,000). Insurers may exclude further subsidence claims for a period. Crucially, the property must be insurable for a lender to proceed. If you cannot obtain buildings insurance, most lenders will not lend. Specialist insurers like Adrian Flux and some Lloyd's syndicates cover previously subsiding properties where mainstream insurers decline.\n\nBuying a Subsiding or Underpinned Property — Commission a Level 3 Building Survey with a structural engineer's assessment. Review all monitoring records and remediation certificates. Obtain insurance quotes before committing. Expect a price discount of 10% to 20% versus comparable unaffected properties. Factor in potential future monitoring costs. The discount can represent genuine value if the problem has been properly resolved.