Subsidence dilemma

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Hi,

I am helping an elderly family friend with his home in London. A decorator/builder pointed out cracks and uneven door frames and said this was subsidence. I contacted a friend who has experience renovating houses who (logically I think) advised me to call the insurance company, since we are lay people in this regard and have them take a look to see if it is or it isn't. I did so, but just getting them to evaluate it involved "making a claim" which made me apprehensive.

OK I've descended into a story, so instead I will just summarise what people have told me, which will hopefully be clearer (though you will see why I am very confused). I have included photos of the cracks at the end.

Friend with experience renovating houses: subsidence he associates with cracks from the base of the property, of which there are none (at least not visible) in this case. He says cracks/movements around doors and bay windows are quite common as these are weak points susceptible to settlement.

Neighbour who has been on the road for a long time and pretty much knows about everything that is happening here: he laughed at me saying these are not cracks! He says they have been there for a very long time (this corresponds to what the family friend/owner of the house says) and they are just the result of settlement. He knows only of one house on the street that had subsidence and this was because of a bad tree the council planted (they are – ahem I mean we are – footing the bill) and says he can’t recall there ever being a large tree outside the family friend’s house. He says he has worse cracks that he is not concerned about at all. He warned about getting a ‘history of subsidence’ on a property (this corresponds with what I have read).

Insurance lady: so at this point I call the insurance lady saying how foolish I am and that this is probably nothing. Interestingly she echoed what the friend with experience renovating houses said about no cracks at the base of the property, saying that based on the description I gave this didn’t sound like subsidence to her. She says not to worry, that the insurance claim can be withdrawn and because the value on it would be zero, this should not affect premiums. However, she asks me to get a builder to look at it just to be sure. In hindsight this seems a bit strange since I don’t think the average builder would be qualified to say, or at least would be unwilling to make an assertion, unless perhaps it was very clear-cut, e.g. superficial cracks in the plaster.

Friend (former estate agent) and her friend, an expert in building materials: This is where it gets confusing. So, I contact the friend to ask if she knows a builder that would be suitable. Her friend, in Poland, is an expert in this type of thing (his company was hired by the government to investigate the collapse of a large hall, under snow I believe), and she shows him the pictures attached to this post. He says this is definitely subsidence! Whether it is ongoing he is unable to say without actually visiting the property. The estate agent friend also said that when she visited properties she always looked at the doorframes and bent doorframes were usually a sign of subsidence.

So what is the dilemma? (Btw, thank you for getting this far!) Well, if this is ongoing subsidence then fine, no use crying over spilt milk, this is what insurance is for. What I am worried about is if this subsidence is old, and not ongoing, i.e. the cause is gone: if the insurance lot come down and make this determination, there won’t be extensive works/costs to them, but they would put a lovely “history of subsidence” on the policy and then changing insurance companies becomes a nightmare and they can charge pretty much whatever they like.

Should I ask the insurance company to commission a structural survey (are my concerns justified?) or should I get a survey done privately (as the estate agent friend suggests) and if there is history of subsidence, but it is not ongoing, perhaps it would be possible just to remove all the evidence (the survey would be a backup to say there is no ongoing subsidence)? Apparently if the survey says it is ongoing (which I think is unlikely) and we then go through insurance, the cost of the survey should be recoverable?

Or is this not subsidence at all? I am totally confused. Thank you for reading! Any suggestions would be greatly appreciated.

Pictures (pic followed by close-up)




The crack in this picture is 3mm – this is the largest one I believe. Note: the family friend/owner informs me that the door in this picture, which appears crooked, was cut uneven by him, i.e. this here is not a crooked door frame, at least not obviously.






Here you can probably see the crooked door frame.
 
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Some pictures of the outside would probably help put things in context.

Subsidence is either ongoing or may have happened due to a problem that has since been fixed. Everything in your pictures looks fairly old and if it was still moving then you would have some much more significant cracks.

This looks like settlement or old movement and I would not be overly concerned, I'd make good and then keep an eye on it - the chances are it is done and dusted.

HOWEVER, I am now expert and we would need to see much more to make an informed decision. My house is 130 years old and has been underpinned due to subsidence which was the result of a failed drain, the underpinning was done 30 years ago and there is no ongoing movement. I do still have cracks like yours in a few rooms which haven't yet been renovated.
 
The problem with asking five different people who have not got a clue, is that you get five different clueless answers

A little knowledge is dangerous, comes to mind.

When clueless people see cracks in a building, the first and probably only thing they say is "subsidence"

I'll give you a tip here. Ask the person to name one or two other possible causes of the cracking. Most people wont be able to. If they do, then ask why they definitely suspect subsidence instead of the other reasons, again, this tends to flummox the clueless

As the bloke from last century says, post up some external pictures, not too close though - of the whole elevation and then places where there are cracks. Also note positions of drain gullies, drain runs and large hedges or trees
 
From the style of architrave, the house looks like 1930's, they were built with shallow foundations and with soft mortar so are designed to move. What you have is absolutely standard for every 1930's house I've ever owned. The house is 'flexible' it's not going to collapse or sink, but polyfilling/ replastering/ replacing coving are jobs that have to be done every 40 years or so.

Don't bother with insurance (if they get involved and comission underpinning, you'll find most potential buyers in the future will be put off).
Having settled, the cracks aren't likely to get any worse. if you polyfill, the cracks will be back within 3 years (hairline only). It would be better to hack the plaster in the affected areas back to brick n replaster, above door frames is a classic weak spot probably not helped by bad bonding of 'breeze' blocks, attach some mesh to the blocks either side of the crack then get replastered.
 
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Thank you everyone.

That is 100% correct - it is 1930s :) I also forgot to mention it is semi-detached.

As the bloke from last century says, post up some external pictures, not too close though - of the whole elevation and then places where there are cracks. Also note positions of drain gullies, drain runs and large hedges or trees

I think that's two centuries ago now?

I will get some pictures of the outside soon, but there are no cracks visible from the outside. No hedges whatsoever; large trees at the bottom of the non-attached neighbour's house (I think the garden is approx 40-50 meters but I will check). Incidentally cracks are mostly near the internal wall between the two attached houses. I will mark positions of drain gullies, drain runs.

My house is 130 years old and has been underpinned due to subsidence which was the result of a failed drain

This is actually what the estate agent friend/her friend suggested as a possible cause.

Don't bother with insurance (if they get involved and comission underpinning, you'll find most potential buyers in the future will be put off).

Would they consider an underpinning if the subsidence is not ongoing? (Presumably if it is ongoing then underpinning is necessary?)

Thank you again for your knowledge.
 
Forgive me, I was wrong, some cracking is visible from the outside at the back of the house. Hope these are ok.


The garden is 30m long (not 40-50 sorry). I have posted a picture of the trees - sorry I don't know anything about trees and whether these are the type with big bad roots.


This one I forgot about before: north bedroom ceiling



By the way, I have titled the pictures in the album to give orientation:

//www.diynot.com/network/lm713/albums/16964
 
There does not seem to be anything there which screams out subsidence.

Perhaps some typical internal movement responsible for the doors, and some thermal (shrinkage) movement for the covings
 
Thank you. It is a relief to hear more people say it doesn't look like anything serious.

The only person I know to be a builder to take a look has (surprisingly) said it is subsidence. I wonder if this is because in Poland the buildings are more solid with deep foundations due to the harsh winters, so even movement of a small degree is considered subsidence. Actually, I have just checked and the word for settlement and subsidence is the same, so we probably just got lost in translation. I will get a builder based here who knows the lay of the land to confirm just to satisfy the insurance.

Thank you all once again for your input. Much appreciated!

Enjoy the weekend!
 
lm713;

Take a look at these pics from my own (1920s) house showing cracks in the same position as yours, bur somewhat larger

Is it subsidence? Possibly

Is it long-standing? certainly - it's been like that for years.

Am I concerned? Not in the least.
 
Just to add something to what the other guys have said.

Subsidence does not necessarily mean cracks originate at the base of a property. It depends on where the subsidence has occurred. If it occurs at the corner of a building the cracks will be far wider at the top and may not be visible at all at the bottom.

Heave causes the opposite problem. This can occur when a tree is removed and dessicated ground swells causing an area of ground to rise up rather than fall away.

Do you know if the ground in your area is clay or granular? Clay tends to be affected by dry weather and/or trees, and granular soils can be affected by broken drains when leaking water washes away the fines.

Much of London is clay but large parts of south London has granular
soils.

If you fill the cracks, a good idea is to use some scrim tape which will help to prevent the cracks reappearing.

People worry far too much about cracks in houses. They are usually nothing to worry about.
 
May I ask a quick question? People often talk about checking the drains to look for signs of subsidence, what exactly does that mean?

Thanks
 
You can get a CTV survey done. This will show if the drain run is damaged in any way; broken, cracked, or roots growing through a joint etc.

Any of the above can lead to water leaking out where it shouldn't, and in granular soils this can lead to the fine particles being washed away in that area, leading to an overall smaller volume of soil in that area.
If this happens under a foundation then the support is taken away leading to the possibility of subsidence.
 
im not entirely sure someone can look at those cracks and tell you its subsidence, whenever ive seen engineers checking it usualy involved attaching glass strips to the cracks and leaving them on for 6 months to see if they break.
 
The glass or plastic tell tales, are monitor the movement, not diagnose it
 

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