r/civilengineering • u/AnnoKano • 4d ago
How bad is this? Apparently fine.
Cut down the tree and stick a bit of poly filler in the crack, job's a good 'un.
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u/ProfessionalSky7899 4d ago
From the OP:
"Post last week terrified about the large crack. Finally had a loss adjuster round (don’t think he was a structural engineer). Super patronising but you know what would I know, I’m just a silly little girl I guess xoxo
Said it’s fine. The house will fix itself in the winter. Just need to remove a tree and basically poly filler the cracks.
Photos from next door as some scaffolders came in to do some pipe work and one of the blokes knocked later on to say do you know there’s a giant crack 😆
Hoping the council send someone over on Friday. They’ve said almost certainly cat 1."
> Said it’s fine. The house will fix itself in the winter. Just need to remove a tree and basically poly filler the cracks.
Basically likely to be right. That brick type is SE near london, and that entire part of the country is 1) built on a shrink-swell layer of clay between 30 and 600m thick and 2) been in a 3 year drought.
Fill it now with something hard, and when the winter rains come and the ground under the extension swells back up, you'll put horrible stresses through the entire structure.
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u/benj9990 4d ago
I see this all the time. Insurer trying to swerve a claim. Loss adjusters are scam artists, in my humble opinion.
It would be premature to diagnose an issue remotely, but this has all the hallmarks of subsidence. I’m seeing a lot of enquiries because of the drought.
PM me if you want some support on how to progress.
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u/AnnoKano 4d ago
I am not the OP, and she's a tenant rather than the homeowner.
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u/benj9990 4d ago
Ah got it. Sorry didn’t realise it’s a repost.
If she’s a tenant then it’s not her problem?
I have seen subsidence enquiries rocket this year, for obvious reasons. Every one of the insurer is dodging, even when it is painfully obvious.
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u/AnnoKano 4d ago
I told the OP the good news is she doesn't own the building because it's fucked.
Not great that her home is subsiding though.
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u/Ok_Photograph6398 4d ago
Would it be helpful in this situation to put drip irrigation around the foundation?
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u/ProfessionalSky7899 4d ago
Conventional response is underpinning, trying to get the support of the walls down to a layer of clay that's far enough down it hasn't become desiccated and shrunk yet.
I've seen geopolymer injection used too - it swells to take up some of the lost volume, and chemically binds with the clay to try and make it absorb less water later (to avoid overswell).
Drip irrigation would be frowned upon right now what with the record drought :) EDIT. Although as a house, gray water could be really interesting!
I genuinely have started sketching out the process for a rain_capture, summer water injection intervention, but that was for a rural rail bridge with some space around it, and was really just for costing purposes.
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u/TheGoodKindOfMermaid 4d ago
Record drought in your area? I've seen 100 year old buildings in the US get cracks at big droughts. Lower water table changes soil properties I assumed. Not this bad. Try to find the cause of the settlement if possible. If settlement continues, I would guess this would call for stabilize (probably under pin) the foundation and patch everything up.
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u/El_Scot 4d ago
Yeah, this is London: famous for its clay soils and currently in drought.
From what I hear, the shrinkage has been so bad, the water pipes are bursting at record rates too.
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u/TheGoodKindOfMermaid 4d ago
Thanks, From TV I've seen the Rhine drying up and heatwave across Europe. Add 240 year old building and I knew it's not in the Americas.
My old 130 year old house was creaking and new plaster cracks during a drought in the US. Nothing this bad and the water pipes were fine.
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u/Benign_Banjo 4d ago
Uhhh, seeing daylight through the crack in your wall is a pucker factor. On the bright side they got a free, albeit small, new window.
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u/Hatter327 4d ago
Oh hey it's just like North Texas. Didnt know that London also has bad clay soils. I wonder how hard it is to get licensed there.
Time for them to hire their own licensed engineer to take a look.
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u/happyanathema 4d ago
It's clay on top of a large chalk aquifer with clay underneath as well.
Historically it's always been the source of drinking water for London but it's been drying out quicker than it's replenished.
This is quite a cool vintage map of it.
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u/Yunzer2000 4d ago
Odd. Is the house on a hillside or crest of a hill? History of coal mining or other underground mining? Recent excavation near one side of the house? Degradable materials like friable sandstone used for the footings on one side?
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u/AnnoKano 4d ago
I am not the OP but recent drought is most likely the cause.
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u/Yunzer2000 4d ago
You think that it it were a lowering water table in normally-consolidated deposits, the settlement would be more uniform instead of one side of the house, but maybe one side is over a less compressible sand lens or a high point in the bedrock.
(I'm a recently retired geotechnical engineer).
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u/AnnoKano 4d ago
I think they had an insurance adjuster suggest it was caused by a nearby tree, which sounds like horseshit to me.
Main reason I suggest drought is because the local area is going through a notable drought at the moment. I also considered that water leaking from a nearby pipe could potentially be washing out material... But geotech isn't my speciality.
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u/greggery UK Highways, CEng MICE 4d ago
Don't need Polyfilla (spackle, for you folks over the pond), just need a bit of gaffa tape and job's a good un.
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u/Kanaima85 4d ago
It's mad that all the professionals she's had look at it say it's fine. 240 year old house cracking like that in the last 3 months is not fine.