Stressed about house subsidence issues - advice gratefully received!

[adamski606]

We bought our current house in March 2025 and I’m feeling pretty miserable and stressed about something that has happened since.
We bought an older detached house in Dorset for £580k. It’s roughly 100 years old and has had a couple of substantial extensions, one in the 1990s and another later in the 1990s.
We had a full RICS Level 3 Building Survey done before buying. The survey was in September 2024 and said there were no signs of unequal movement externally or internally and no evidence of distress around the rear extension. It did mention some normal movement over the lifetime of the building and some old cracked/uneven ceilings, particularly in the older part of the house, but nothing that the surveyor considered indicative of structural movement.

We also didn't notice anything concerning when we viewed the house or during the months after buying it.

Over the summer, though, we've noticed some fairly substantial new cracking in one corner of the house. There is a large crack internally around the ceiling/wall junction, with some vertical/diagonal cracking, and externally there is cracking through the render and into some of the concrete blocks.
It seems to be quite localised to one corner rather than cracks appearing all over the house. There are no obvious signs of the house being unsafe but obviously seeing a fairly substantial crack in your house is horrible.

We've contacted the buildings insurer. Their inspector came out and was fairly confident that it could be subsidence, although they haven't formally confirmed that yet. They have now instructed a firm of structural/ground investigation specialists. The insurer has said they will share the reports with us

.
I'm trying to be rational about it, but I'm finding it really upsetting. I can't help feeling incredibly unlucky that we've apparently developed this problem shortly afterwards.

I think what's worrying me most is the thought that this could turn into a massive, expensive problem, that the house might need underpinning, or that it will be difficult to sell in the future even if it's repaired.

Has anyone been through something similar, particularly where subsidence appeared relatively soon after buying a property that had a clean survey? how bad did it actually turn out to be? Was it ultimately something relatively localised and repairable or did it become a much bigger job?
And for anyone who has had a subsidence claim: how did the monitoring/investigation process work and how long did it take before you actually knew what was happening?

I'm not really looking for people to tell me that I should have spotted it before buying – I'm already kicking myself enough! I'm mainly looking for some real-world experiences of what happened after the initial panic.

I'm particularly interested in experiences several years down the line – whether you were able to get the house properly repaired and insured/sell it normally afterwards.

I know nobody can diagnose our house from a forum post, but I'm hoping some people might be able to reassure me that “possible subsidence” doesn't automatically mean you've bought a write-off!

TIA

I had subsidence appear a couple of years after I bought a house of a similar age. Apparently it's becoming more common now with hotter summers.
For me, it was due to the roots of nearby trees running into the drains under the house. It felt like it took ages to get sorted but it was right over lockdown so I'm not sure it was representative (the thing that took longest was trying to get the housing association who owned the trees to respond, and the water company to give access to the drain).
Trees were removed, drains were fixed and monitoring put in place. All was ok and I got a structural certificate. I paid £1k excess but insurance barely went up over that which surprised me. Sold it 2 years ago with no issues, I just had to provide the structural certificate.

I had similar and went through insurance. It was monitored for 3 months, they said it wasn’t subsidence but suggested I get a cracked drain looked at.

I wasn’t convinced they did a thorough job as another surveyor said it should be monitored for at least 12 months, so im doing some monitoring myself!

I didn’t get a structural certificate which worries me now!

We had subsidence, fixed during renovations and a big wisteria removed sadly, it had been sucking all the water out of the clay soil under that side of the house. I don’t think underpinning is as big a deal as you might be imagining.

I'd be suspicious of the really long dry summer that's caused it. Sometimes these things can close up on their own once the soil gets back to normal over winter.

Builder here, nearly 30 years in the trade, and I've been on the repair end of quite a few of these claims. Try not to panic. Most subsidence claims on houses like yours turn out far less dramatic than people fear.

How it usually goes:

• The specialists normally start with a CCTV survey of the drains near that corner and a look at any trees or big shrubs nearby, yours and the neighbours'. Leaking drains and tree roots on clay are the two usual suspects.
• They may dig a trial pit beside the foundations and take soil and root samples to pin down the cause.
• Then monitoring, usually level readings or crack gauges every month or two. Expect 6 to 12 months, because they want to see a full wet and dry cycle. Cracks that open in summer and close up over winter point to clay shrinkage, which fits the dry summer we've had.
• The cause gets fixed first (drain repair, or a tree removed or reduced), then they monitor again to show it's stable.
• Underpinning is normally only needed if the cause can't be removed or the movement carries on. A lot of claims end with the cause sorted, the cracks stitched and the rooms redecorated.

On the extensions: 1990s extensions often sit on foundations at a different depth to the original house, so cracking where old meets new is common and doesn't always mean the main house is moving. Worth asking the investigators about that specifically if the corner is near a junction.

Things that will help you later:

• Keep every report, the monitoring results and the engineer's final certificate of structural adequacy. That's what a buyer's solicitor and future insurers will ask for.
• Stay with the same insurer if you can. Insurers will usually keep covering a house they've repaired, and switching straight after a claim is harder.
• Don't fill or paint over the cracks yet. Take dated photos with a ruler or coin next to them so you have your own record.
• If a neighbour's tree turns out to be the cause, the insurer deals with that, not you.

Plenty of houses with a past subsidence claim that was properly repaired and signed off sell perfectly normally. It's the unresolved or undisclosed ones that cause trouble.