Potential subsidence in SE London

[AdamAntlers]

Hi,

id really appreciate any advice from anyone who has experienced this. DH and I aren't from the UK and don't have any experience of subsidence.

we bought a 1930s semi in Kidbrooke in 2018. It had an extension on the back (permitted development) and the extension had some hairline cracks where it met the old house. We had a full structural survey done which found no problems.

this year, we came back from holiday to find a massive crack (£1 width) running along the ceiling where the extension meets the old house.

we keep getting different advice from people:

• we found a surveyor online who said it's due to trees near the house. He said it's best not to involve insurance, cut down the trees and repair the damage
• our neighbour on one side says he has the same. He had a trench in his garden, they found tree roots and cut the trees. He says no repair is possible/ necessary and it will eventually fix itself
• Our neighbour ob the other side said that we need to underpin the whole house and prepare to lose 30% of the house value.

we're basically petrified. Our biggest concern is preserving the sales price of the house - since we only bought 4 years ago, it hasn't increased in value much. if anyone has any insights, I'd really appreciate it

very few houses are actually underpinned these days.It’s a last resort situation. If your London based you probs have clay soil which is known for subsidence especially where trees are involved. The dry weather will not of helped as if you have trees near, the roots will spread looking for water.

We have just had work done on our house following a subsidence issue. House was monitored for movement for 3yrs after the initial shift. They removed trees, plants and had a look at the drains. They don’t under pin. They put metal bars in some areas depending on size of cracks .our street had a few houses affected following a very unusually hot summer. Once the work is completed you get a certificate so shouldn’t affect any sales going forward

Thank you for replying! This is the gist of what our neighbour said. Would you recommend a trench to find the cause or is it so likely to be a combination of trees/ clay that it's not worth it? We have a huge willow and several sycamores which predate the house along ours/ our neighbours gardens.

Thank you! The original surveyor mentioned that he could issue a certificate to show the subsidence had been properly rectified but he said he could issue it immediately following repair work.

did you go through your insurer and if you don't mind me asking, was it very expensive?

Not sure in terms of a trench. A structural engineer would be the best bet before insurance. I personally would avoid insurance until I knew the facts. Just be careful removing trees that predate the house as this can cause heave. You ideally need some proper advice from SE and if trees are the cause a tree surgeon. Might be worth a drain cctv also if you have drains near by.

Willow trees apparently are awful for subsidence.

We went through our insurance. We had work done outside and inside and nearly every room had evidence albeit subtle so had small cracks widened and sealed too. We paid 1000 and insurance the rest.

Thank you. No one had mentioned the possibility of heave, I'll ask the next surveyor about it.

can anyone recommend a structural surveyor in SE London?

glad it worked our. Ours isn't cracked all over the house, just the line where the ground floor extension meets the old house

We have the same in our house too so not sure what the next steps are. We've got a drain survey booked in and trying to get hold of a tree surveyor!

AdamAntlers sounds more like a structural problem than subsidence. if it is related only to the extension.

I am in SE London too- I will
see If I can find the details of the surveyor

I would suggest involving a structural engineer, and probably a different surveyor. A competent structural engineer should br able to discuss options to repair the damage and more importantly, to stop it from getting worse.

The surveyor who suggested not involving insurance sounds possibly dodgy. If it’s about not making an insurance claim, fair enough, but if it’s about concealing the problem, that would be dodgy.

The neighbour who said it would ‘fix itself’ sounds deluded. Cracks don’t fix themselves. Gravity is one-way.

I think, regarding the insurance, people are sometimes advised to do their own investigations, before involving them. Apparently once a house has been investigated for subsidence, it stays on file and can put the policy up, even if it's proven the cracks are due to something else. I'm not sure how true this is, and seems ridiculous to me... but worth looking into.

If it is subsidence there's generally a 1k excess on most insurance policies.

You just hand this over to your house insurer and let them sort it.

i should add that I got builders round initially and they immediately told me to go through my insurance company. I haven't had any hikes in monthly cover zilch.

A few houses on my street have been sold and had no issues at all with selling. They had the subsidence work completed a certificate of completion. No drop in price nothing. You need to seek professional assistance and stop listening to neighbours who clearly have no idea.

My house has suffered from subsidence since we owned it. We initially paid for a surveyor to come and have a look at the cracking , but once he agreed that it probably was subsidence, he suggested we went through the insurance company for further investigation.

They did a lot of investigations which would've cost a fortune – drain survey, dug pits near to the house to look at the foundations, and took soil samples to analyse (both to determine the type of soil but also a giveaway was the amount of moisture in the soil samples and traces of sewage and soap suggested it was indeed a drain issue ).

It would cost a huge amount to have a specialist to come and do all of that (our claim for repairs was £20k, paid only £1k excess).

Plus if subsidence is agreed, then when you do come to sell, and if you're not upfront about it, you could find yourself in a lot of trouble, if ever it came to light.

Or what if you fixed it, and then it came back a couple of years later and you decided you'd have to get insurance in to do it properly this time, how would you explain to them what had happened before? They might decline your claim on the basis that you'd known about it all along but not told them.

Far better to be honest in my view. Plus if there's ever an issue in future, all I have to do now is phone the insurance company and they'll send somebody straight here. I wouldn't even have to pay any more excess.

Just call out your insurer. As a PP has said, it's not something you want to be anything less than upfront about, in case it turns into bigger problem.

If it proves to be subsidence, it might put your insurance premiums up slightly (but you'll be glad to have cover), but it won't if it's nothing.

It's been a very hot summer; many, many people are going to be having the same issues,

I would get a surveyor to come and look at it. We bought a house with suspected subsidence on the (separate) garage and insurance claim in progress.

Whilst the actual claim/repairs in the end were not expensive (£3k), you had to keep declaring the subsidence on the insurance and stick with the same insurer each year. And then obviously disclose when you sold. Even though we subsequently knocked the garage down....

I'm not saying don't tell the insurer, but I would get someone independent to take a look at it first just in case it's something else.

Thank you so much for all your answers.

I used the RICS find a surveyor tool to find surveyors specialising in structural issues in my area and contacted them all. A few declined and a few have offered initial consultations.

what confused me the most was one of them said that this was not a job for a structural surveyor, but a structural engineer. I asked a different surveyor and he said that some banks preferred structural engineers to sign off on the works before offering a mortgage backed by the property but others preferred structural surveyors?

would anyone know which would be best to go with?

the (slightly) good news is that based on the position of the cracks and our area, a few have said it might be movement under the extension rather than subsidence.

I'll take on board the advice to involve my insurer - as you say they may reject a later claim based on not disclosing an issue. However, I'd prefer to have a qualified opinion first before I speak to the insurer. My insurance is with Ageas, does anyone have experience with them?

bump

You want a structural engineer.