Somerset and Devon clay soils are among the most susceptible to subsidence in England. When the clay dries out in summer, it shrinks — and foundations move with it. If you have noticed new cracking, sticking doors, or a structural survey has flagged foundation movement, this guide explains what underpinning actually involves, what it costs, and whether your insurance will pay for it.
Why Somerset Properties Are Particularly Prone to Subsidence
Somerset sits on a significant layer of shrink-swell clay, particularly in the Vale of Taunton, the Somerset Levels fringes and across South Somerset. During dry summers, this clay contracts significantly. Older properties built with shallow strip foundations — as virtually all pre-1970s homes were — experience foundation movement as a result. The summers of 2022 and 2025 produced more subsidence insurance claims in Somerset than any period since 2003.
How Do You Know If Your Somerset Property Has Subsidence?
- Diagonal cracking from the corners of windows and doors — typically wider at the top than the bottom
- Cracks that are wider than 5mm and appear to be growing
- Doors and windows that have started sticking despite no recent changes to humidity
- Visible tilting or stepping of brickwork courses
- Floors that feel uneven or are sloping noticeably
- Cracking that mirrors on both inside and outside of the same wall
Note:Important: Not all cracking means subsidence. Settlement cracking in new builds, thermal movement cracks and shrinkage cracks in plaster are all common and not structurally significant. A structural engineer assessment is the only reliable way to determine whether underpinning is required.
Types of Underpinning Used in Somerset
| Method | Best For | Typical Cost |
|---|---|---|
| Mass concrete (traditional) | Most residential properties | £1,200 – £2,500 per bay |
| Beam and base | Deep clay profiles, two-storey properties | £2,000 – £4,000 per bay |
| Mini-pile | Restricted access, unstable ground | £3,000 – £6,000 per bay |
| Full project (typical 3-bed terrace) | Complete underpinning | £8,000 – £30,000 |
Will Insurance Pay for Underpinning in Somerset?
Most building insurance policies cover subsidence and the resulting underpinning works, subject to your excess (often £1,000–£2,500 for subsidence claims) and the insurer accepting the cause of movement. You will typically need a structural engineer report confirming the cause before the insurer approves the repair. We are experienced in working within the insurance claims process and can coordinate directly with your loss adjuster throughout the project.
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