[Closed] Movement in a house

Sounds like subsidence caused by vegetation. Clay soil? Cracks will be biggest now and close by may. Insurance for you... And a long and stressful battle

Some clay soils change in volume depending on soil water content. Cracking occurs during drought and/or a period of high rainfall.

How far away are the trees and what are they? Some have a main central root that goes straight down and others have more horizontal root systems.

Could well be soil related if you are on clay. We have an old (1910) house with effectively zero foundations. Next door (semi detached) and our house both have new extensions with metre-deep foundations to the gravel bedrock. Both houses move (sticking doors etc) and walls crack in the summer as they clay dries and shrinks, then move back in the winter when the soil gets wetter. I regularly watered the ground around the house this summer, and the problem definitely improved.

Hopefully accepting an offer this week, so we won't have to worry about it too much longer!

The surveyor made a point of stressing that he didn't consider it subsidence and not to bother going down insurance route for reasons that it devalues house even after work has been carried out and he didn't believe it needed doing. He said that it's just seasonal movement and that until the tress are properly managed it will keep occuring, plus we are on a steep hill. Although we have just as many cracks along rear wall of house where there are no trees which he could identify the source of.

I dont really want to get into a fight with the insurance company without it being actually confirmed first independently that it is subsidence for the reasons above, but it needs addressing as it becoming something that I'm losing sleep over and spending too much of my time coveribg. It's really disheartening to be constantly filling cracks!

I believe the house is built on previously made up ground with a clay substrate.

So that's more likely to be your problem than a few trees. Cracking from tree roots will be localised and related to the root pattern.

We get a few small cracks here and there with the seasons. Sometimes nothing, sometimes a bit. Doesn't worry me. I know the drains and water are ok. No mining or secret caves. Just clay soil, old house and a few trees around. It's been up nearly 100 years and it's still here.

Hopefully, given the date your house was built, they used a lime mortar rather then a Portland cement. Lime is a more flexible substance. Houses move depending upon the local soil type and other factors. The house is 80 years old and still standing, result.

Cracks due to trees can be throughout the house even with trees 'affecting' one corner. The corner dropping pulls on the whole structure and damage radiates. I have it, every wall of the house but the trees causing it are only to the rear.

There's no real risk asking the insurance, check your policy but normally they investigate for free and trust me, if they don't think it's subsidence they won't say it is, but from your description.... I'd be surprised if it's not subsidence caused by shrinkage of clay soil desiccated by vegetation. It's easily sorted if the owners of the vegitation comply with requests to remove or reduce. If they don't.... Then you have a problem.

Is that a 4" gap or 0.4"? 4" would be quite significant.

A relation of mine who works for a large building firm says that insurance are not interested unless cracks are larger than 10mm (becuase all house move to some extent)

Might be worth looking into rain water harvesting to keep a resevoir to irigate the clay substrate. If the narby tress are taking some moisture then it may well be heave or movement casued by the clay shrinking
wetted clay expands and the forces involved are substantial when it hydrates
Keeping it wet all year helps stabalise the clay water content and reduce movement
I dont think tree roots like pushing through thicj lay that much and either go above or round clay bands , but I could be wrong on this
You would need a way to be able to monitor the moisture of the earth and then a way to get water around your property
I dont knoow if underpinning can be seen without a mini digger tbh so the strutual engineer would be up against it

A "trees height to foundation subsidence ratio" is generally 1.5 times the height of the tree i.e an 8m high tree will have a zone of influence of roughly 12m horizontally. Clay does indeed shrink and swell by potentially up to 60% by volume, living at the bottom of a steep hill you may be subject to "soil creep". Your house is almost 90yr old so I would not be too concerned. For general settlement on building structures 20mm is a bench mark number where geotehcnical/structural engineers would be concerned (lesser amounts are generally due to thermal expansion & minor settlement). You could dig a trial put down the outside wall of the house and easily identify if previous underpinning has occured. Housing settlement is usually due to insufficient foundations, trees drawing moisture out the ground in summer and broken utility pipes. If the cracks cut through the mortar that's not a big issue, if they cut through the bricks/blockwork that's more of a concern. Hope this helps a little (I'm a chartered Geotechnical Engineer).

ackalice

Subscriber

Hopefully, given the date your house was built, they used a lime mortar rather then a Portland cement. Lime is a more flexible substance. 

Why do we get lost redarding lime mortar on any building thread. Founding of any building on whichever substrate varies hugely and has nothing to do with lime mortar. Internal finishes would not, unless wattle and daub (piss take) benefit from "lime mortar".

Had fairly major subsidence (finger width cracks you can see daylight out of) in the summer of 2018. Never before that, and since then it's got worse and got better depending on the weather. At some points we physically could not shut our back or front doors because the frames were like parallelograms!

In my case, the cause is clay soil and a neighbour with a massive load of oak trees they have not been maintaining. 👍

Trees now felled at our insurers expense (ongoing battle), and we are waiting to see how much it recovers before getting they house redone. Looks like we'll have to move out for three months. Floors up, kitchen out, bathroom out,
drains all dug up and redone, windows out and refitted, walls tied back together then re-plastered. The lot basically. Everything except underpinning.

THe biggest cost to us so far is £1000 for our excess and our yearly insurance bill going from £200 to £900. I managed to talk them down to £600 but until the claim is resolved even specialists wont touch it.

The insurer has spent shit loads, at least £3K removing the trees, £4k on soil analysis, drain examinations, boreholes and something else I've forgotten. Inspection of the house every month, many many temporary repairs.

Although unpleasant retro, I wish I were in your situation. I've been at this 11 years and neighbours still haven't removed their f'in trees. I'mm taking the insurers off to the ombudsman again shortly in all probability. Stressed, i am.

Wow, sound like some real nightmares going on.
The trees are easily 10m high and within about 8m of the front of the house.
We aren't at the bottom of the hill, we're half way down. But end of a terrace.
The surveyor checked resins and was happy they were ok.
I'll probably have to go down insurance route.

Yes, gap between external wall and internal dividing wall was 4 inch at bottom. It was covered by old kitchen units and wall was backing on to under stairs cupboard so couldn't see it.

You still haven't answered the question about what sort of trees they are, it's not only distance the tree is from the house but also the type of tree. A 10m silver birch at 8m from your house is highly unlikely to be the source of the problem however an Oak with a deep central root drawing water from low down might be, it's still a small tree though with limited impact. Anyhow have a read, I'm not happy with coconut's 1.5 x height but rather than argue I'll just post these and let you read for yourself:

http://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2011/Part4/section2/default.htm

http://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2011/Part4/section2/appendix.htm

There's a table for distance affected in relation to tree type in the first link and a tree type table in the second link. Combine the two and you'll be able to calculate how much impact the trees are likely to have.

And how steep is the slope?

Not all clays shrink to the same degree. Which geographical area is the house in?

neilnevill

Member
Although unpleasant retro, I wish I were in your situation. I’ve been at this 11 years and neighbours still haven’t removed their f’in trees. I’mm taking the insurers off to the ombudsman again shortly in all probability. Stressed, i am.

Posted 8 hours ago

Thanks mate, your situation sounds horrendous. Have the trees been proved to be causing a problem in your case?

I think a case can in theory be made regarding nuisance, in my case the insurer was unwilling to go to court because it was too expensive.

Proof? Well plenty of evidence yes, everything short of DNA of roots and the remaining trees. As you say, insurers are reluctant to do anything more then periodically plaster over the cracks, which is why I'll be off to the ombudsman again shortly in all likelihood.

Subsidence claims don't progress swiftly but 11 years is taking the biscuit.

Btw I understand that watering could make things worse as it can attract more tree roots into the area, so actually resulting in more water removal. At least they was my understanding of why my insurers lined a drain on my property which had nothing wrong beyond a slightly misaligned joint. They wanted to ensure there was no potential for a slight leak to attract more tree roots to the area and make the potential for subsidence greater.