Does Underpinning Devalue Property?

Written by Millie Archer

I love all things property and have a real eye for detail. I’m always reading up on property news, whether it be renting a first property or buying a mansion.

Explaining what underpinning is, what the costs are and answering 'does underpinning devalue property'...


In 2021, subsidence claims increased by 49%, according to SOLD.co.uk, meaning the chances of your house being affected by subsidence is quite high. Underpinning a property can be extremely costly and it also raises the question ‘does underpinning devalue property?’ – something you will want to know when selling your house.

We’re going to answer this question, alongside talking you through the cost of underpinning a house and what are the key signs of subsidence in a house that you need to look out for.

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What is underpinning?

Underpinning is a technique to correct properties that have suffered from or are suffering from subsidence, causing weakening of the property’s foundations.

Underpinning will strengthen these foundations, as this is a necessary repair to a property affected by subsidence. The process involves removing soil from beneath the property that has been moving away. The soil is then replaced with stronger materials and deeper footings to stabilise the property and the property’s structure.

Essentially, underpinning involves weakening the property’s damaged foundations in order to put in newer and stronger foundations, stabilising the property’s structure.

There are many different types of underpinning and which type is best will depend on your property and its situation. The different methods of underpinning are:

  • Piling – Piling consists of piles being placed into the ground on more stable soil, rather than the weak soil the property’s foundation is currently on
  • Beam and base – Beam and base, also known as pier and beam, is where reinforced concrete beams either replace or reinforce the existing footings, by helping to disperse the weight of the property onto the more solid new beams
  • Cantilever needle beam – This method is faster and less disruptive than other underpinning methods, as the work takes place outside the property
  • Jet grouting – Jet grouting acts to strengthen the weakened existing soil beneath the property foundations. High-pressure jets mix the soil with grout to create a stronger base for supporting the foundations. A similar method to this is called ‘resin injector’, where a resin mix is injected into the ground, causing a chemical reaction and therefore expansion once it enters the ground. The expansion strengthens the ground by making it level again
  • Mass concrete – Mass concrete is the most common method of underpinning, and it consists of deepening the current foundations and filling the area below with concrete

Why would a house need underpinning?

A house would need underpinning as a result of being affected by subsidence. Subsidence occurs if the ground underneath a property begins to sink or cave in, which results in the property moving or sinking.

Subsidence can be particularly problematic if the ground and foundations underneath the property are sinking at different rates as it causes the house to become misaligned.

What causes subsidence?

Subsidence can occur as a result of a number of different causes. The most common cause of subsidence is tree roots. Tree roots that are planted close to your house will absorb water and moisture from the soil, causing the soil to dry out and shrink. As a result of this, the ground is destabilised.

Another cause of subsidence is the weather altering the ground underneath your property. When the weather is wet, the soil expands and when it’s dry, the soil contracts. After a long period of dry and wet weather, the constant fluctuations between the soil expanding and sinking will cause the soil beneath your property to become unstable.

Properties that have been built in areas that have previously been used for mining or as quarries are susceptible to subsidence. This is because these areas already have weaker and more unstable foundations and so are more likely to sink below your property.

Leaking drains and gutters are another cause of subsidence. Water leaking into the soil under your property will wash away the soil foundations, causing the ground to be unstable and sink below the property.

A final cause of subsidence is the soil type that your property has been built on, with clay soil more likely to suffer from subsidence. Soils that have high sand or gravel content are also vulnerable to subsidence, as they can be washed away from the foundations, leaving the property weak and unstable.

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Signs of subsidence in a house

There are a number of warning signs of subsidence in a house which you will need to look out for so you’re able to act fast if your house displays any of these signs:

  • Large cracks in the wall – one of the big signs of subsidence in a house is large cracks, thicker than 2mm, in the walls of a house. The cracks are normally visible both externally and internally and tend to be in a diagonal direction, getting wider at one end of the crack
  • Large trees close to the property – having large trees close to your house can mean the roots cause disruption with the property’s foundations, as they dry out the soil leaving it unstable and more likely to move
  • Older foundations – another one of the warning signs of subsidence in a house is if your property is built on old foundations. Old foundations are less deep than newer ones, meaning properties on old foundations are less secure and therefore more likely to move and be affected by subsidence
  • Torn wallpaper – torn wallpaper is a tell-tale sign of subsidence in your house, as wallpaper will crinkle and rip on walls and around joints if the property is affected by subsidence, as it will cause walls to move
  • Mining history – if your property is built in an area of mining history then it will have an increased risk of subsidence, due to the mining weakening the earth and foundations of the properties nearby
  • Clay soil – if your house is built on clay soil then this is another one of the signs of subsidence in a house. Clay soil actually makes up an estimated 80% of subsidence claims, as the soil is prone to cracking and movement during warm, dry weather, unsettling the property’s foundations
  • Windows and doors sticking – as a result of subsidence, windows and doors can start to stick in their frames as they can warp due to the movement
  • Water leaks – the final of all the signs of subsidence in a house is to look out for any water leaks, as the water will saturate the soil, causing it to become unstable


If you spot any of these signs in your house, don’t panic! It doesn’t necessarily mean that your house is affected by subsidence, but you should get it checked out so you’re able to get the best advice on what to do.

Cost of underpinning a house

Naturally, the cost of underpinning a house will vary dependent on the size of the property, with a larger property bringing higher costs due to the larger footprint.

Also, the job will become more expensive should there be any complications, such as the area being difficult to access.

The table below gives you the cost of underpinning a single wall in a property using three different methods of underpinning, so you would have to multiply the amount by the number of affected walls to get a better idea of how much it will cost:

 Job description  Duration  Mass concrete  Mini piling  Resin injector
 Underpinning a single wall in a 2-bed terrace (4m)  3 weeks  £6,000  £10,400  £4,800
 Underpinning a single wall in a 3-bed semi (5m x 4m)  4 weeks  £13,500  £23,400  £10,800
 Underpinning a single wall in a 4-bed detached house (8m x 6m)  6 weeks  £21,000  £36,400  £16,800

Statistics from ‘Myjobquote’

On top of these costs, there are also likely to be added costs for extra professional help, such as a structural engineer needing to inspect your house regularly, before work is carried out, as they may need to examine and assess your soil and run further testing into the property’s foundations.

Does underpinning devalue property?

Underpinning will devalue a property, but there’s no set amount it will devalue it by, as it will depend upon how bad the subsidence was and how recent it has been affected by it.

Generally speaking, underpinning will devalue a property by about 20-25%. On top of this, it can be more difficult to find a buyer on a property that has been underpinned, as a lot of people don’t want to take on the risk of subsidence reappearing.

Also, subsidence will mean that lenders don’t want to lend on the property meaning you will need to find a buyer who doesn’t require house repayments, which are harder to find.

So, in short, the answer to ‘does underpinning devalue property?’ is yes it does AND it makes it harder to sell, not a great combination.

Do you have to tell buyers about subsidence?

It’s crucial that you’re open and honest with buyers about any problems your house has had with subsidence, even if it has been fixed with underpinning. It is actually a legal responsibility of yours to share this information on the Property Information Form, known as TA6.

If you’re not honest with your buyer and they later find out, it increases the risk of them gazundering you or, even worse, pulling out of the sale altogether.

Also, if you don’t declare any underpinning that has been done to your property, you could be taken to court, as buyers are protected by The Misrepresentation Act 1967.

Also, if you’ve had your property underpinned you will want to share the completion certificate with your buyer, as well as how long it has been free of subsidence issues, to reassure them about the property.

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How to sell a house with subsidence

As you would expect, selling a house with subsidence comes with a lot of issues, mainly that a lot of lenders will refuse to lend on this type of property, meaning you will have to find a buyer who doesn’t require house repayments.

You will also face the problem that a lot of buyers won’t want to buy a house affected by subsidence, even if the house has been underpinned, as there’s still more risk with this kind of property.

Even though it’s difficult to sell a house with subsidence, it’s not impossible, though it may feel it at times. Below are the best methods to sell your house with subsidence:

Auction

Selling your property through auction is one of the options which may make selling a house with subsidence a little easier. At auction, you will be met by a large number of buyers, meaning the chance of someone wanting your property increases.

When the hammer comes down on a deal, your buyer will put down a deposit and exchange contracts immediately. The buyer then has 28 days after the auction to complete.

Selling through auction requires minimal effort from you – all you have to do is pick the auctioneer, host an open day prior to the auction and set a reserve price.

However, at auction you will be presented with buyers who are all hoping to get a house for a ‘good deal’, meaning that houses at auction do tend to go quite a bit below the ‘market value’, especially if your house has subsidence.

On top of this, you will have to pay a percentage of the sold price to the auctioneer, as well as covering room hire, marketing costs and all legal fees yourself.

There is also no guarantee of your reserve price being met, meaning your property may end up not selling at all.

Cash buyer

Another option you have when it comes to selling your house affected by subsidence is to sell to a cash buyer. A cash buyer doesn’t require any kind of external funding from a lender, making them an ideal buyer for this type of property.

Due to cash buyers having funds readily available they can complete in quicker timescales and there’s less paperwork involved, with good cash house buying companies handling everything and only requiring a signature from you.

Also, with cash house buying companies, the sale is a guaranteed sale, meaning you don’t have to deal with any timewasters or buyers who will pull out close to exchange.

If this sounds like the ideal route to sell your house with subsidence, then we can help you out!

Here at The Property Buying Company, we’re a cash buyer of houses buying any property in any location and any condition – so no need to worry about subsidence or underpinning!

We can complete in a fast timescale of your choice, and we will cover all the fees for you – yes, no estate agent or legal fees here!

With us, you can choose a timescale to suit you, with our average completion timescale being 2-3 weeks! We will handle everything for you, meaning all you need to do is ‘sign on the dotted line’.

We only require one quick viewing of your property to check our cash offer is accurate and we’re a guaranteed buyer, meaning once you’ve accepted our offer, you will receive the amount in FULL.

On top of this, we’re members of The Property Ombudsman and the National Association of Property Buyers, as well as being highly rated on major review platforms, meaning with us you’re in safe hands!

Selling a house with subsidence doesn’t need to be difficult – just give us a call or fill in our online form today for a no-obligation cash offer which we can have in your bank as soon as you need…

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