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Understanding subsidence – a practical guide

Subsidence is a scary-sounding condition. Thinking of the ground shifting beneath our feet and causing our homes to sink would quite rightly make most people feel uneasy.

Yet this condition affects many houses in the UK – up to a fifth of them, according to some studies. While it could develop into something serious, in most cases, homeowners can manage subsidence with an effective ongoing treatment plan.

Here, we’ll explain what subsidence is and why it’s particularly essential to be aware of it when buying a house.

What is subsidence?

Subsidence is the ground level beneath a building lowering – or ‘subsiding’. As the ground falls, the home on top of it drops down too.

There are a few different subsidence causes, but most relate to the soil’s water content. As the ground loses water, it shrinks, compacting down into a smaller volume. This makes the property above it – foundations and all – lower a little.

The most significant root issue (no pun intended) is trees, as the roots absorb large quantities of water from the ground. It’s particularly bad in dry weather, as the trees search for moisture to survive.

This type of subsidence is usually caused by soil with heavy clay content. The clay absorbs moisture and is particularly prone to swelling and shrinking during wet/dry times, respectively. This phenomenon is known as shrink-swell, with the shrinking aspect leading to subsidence.

Other causes could include:

  • A change in the direction water drains through the soil.
  • Living near a mine (active or discontinued).
  • Damage to nearby drains or underground pipes.

What are some signs of subsidence?

As a potential homebuyer, it’s always crucial to keep an eye open for any signs of subsidence when you view a property.

Some of the major things to look out for include:

  • Big diagonal cracks in the walls, greater than 3mm.
  • Cracks visible in plasterboard and brickwork outside.
  • The cracks are usually wider at the top and near doors or windows.
  • Wallpaper ripples.
  • Doors or windows won’t open or shut properly.

In the UK, according to the British Geological Survey, the South East is the worst area of the country to be affected by shrink-swell issues, as the clay found in its soil is young and ‘soft’. As such, you should be especially on the lookout in this area.

A good approach would be to research the history of subsidence in the local area before viewing any houses.

Can you buy a house with subsidence?

If you find signs of subsidence and a survey confirms its active presence, can you still go ahead with the sale?

Yes – but mortgage companies probably might not be willing to help you. This is because the building will be very susceptible to severe damage, which would make their loan insecure. As such, most homes sold with active subsidence are sold to cash buyers.

If a survey, or a look at the property’s history, finds evidence of historical subsidence – that is, it suffered from subsidence in the past but has since been treated and fixed – it should be technically possible to get a mortgage and insure it. However, it’ll be much trickier than a standard property, and you may have to chat to several providers.

Is it worth it to buy a house with subsidence?

Buying a home with subsidence could be a fairly high-risk move. It would be impossible to say, on a broad basis, whether buying one is worth it or not. Instead, we’d recommend hiring a professional surveyor to inspect the house and give you an honest opinion on how you should proceed.

Most cases of subsidence are manageable. In fact, it’s estimated that only a tenth of homes suffering from it need to be underpinned (digging out the soil underneath the foundations and replacing it with new material such as concrete).

Repairing subsidence could cost anywhere from a few thousand pounds to £50,000 or more, depending on the severity of the problem. As such, hiring a chartered surveyor to analyse the situation for you is usually a sensible investment.

If you’d like to get in touch with us for a brief chat about subsidence or to arrange a home survey, you can contact us through email (contact@gbhomesurveys.co.uk) or phone (03333 600 685).

Looking for a quote, or maybe you have a question? Get in touch today.

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