My neighbours' insurance company claim that my shrubs caused subsidence of his extension

procleon

My neighbours have a single story extension that forms approx 60% of the west boundary of my garden. Our houses are on a hill and the level of their house is about a metre below mine and the extension built in 1988 was built right up to the retaining wall that marks the end of my property. There is one of those high up the wall, long narrow windows in the extension wall - it is not very high up from the point of view of my garden! I knew the extension was there when I bought the property but I did not know the window was there until I saw the light from their kitchen shining through the very thick, mature bush in front of it!

My structural survey in 2004 did not mention the extension as a problem; it did not mention the shrubs growing against the wall and it did not mention the oak tree at the bottom of the garden.

This year my neighbour pointed out a crack in the front wall of his extension. We are in a small close of six houses and no. 2 has been underpinned for subsidence. He did not say that he thought I was to blame for the subsidence, so I made sympathetic noises and thought no more about it.

Recently I received a report from arborists working for the Technical Claims Consultants for his insurers which says that the damage relates to clay shrinkage as a result of moisture extraction by roots. As a first step they want  all the shrubs on the boundary removed to provide 4m clearance; they say "given their overall size and transpiration rates" it is unlikely "they will be the dominant cause of movement". But their removal will expose me to the ugly flat roof extension and the window in it. It will also destroy the appearance of my back garden and destroy a rich source of food and habitat for birds and insects. They are perfectly ordinary shrubs - buddleia, mock orange and forsythia, myrtle - not the ones I think of as dangerous and they have been there since before 2004. The next step will be to dig a pit to test whether the real culprit is the oak that grows at the end of my garden. It is very old and the report puts its height at 16m and distance from my neighbour's house at 18m. The report says that the tree does not have a protection order but that the council would likely put one in place if anybody requested it. The report suggests regular pruning to maintain the tree's height. 

I have reported the claim to my buildings insurers and made an owner liability claim, but clearly the problems will persist for at least two years and I wonder how easy it will be for me to get insurance next year. Claims for underpinning may come two or three years in future and will I have insurance cover then? I resent the fact that the whole liability for the problem is being unloaded onto me, with no consideration of the possibility that poor construction of the extension may be a contributing factor. The crack are confined to the extension as far as I can tell. The repot indicates the extension's foundations are 0.8m and we are on very shrinkable clay.

Any advice? M

pbartlett

fior each shrub, google root damage

buddleia can be problematic for example

TELLIT01

Buddleia would be the only one I would have any major concerns about.  Their roots can be thick and widespread.  If it has been there for the best part of 20 years I would expect them to be both. 

Your insurer may want to get their own report but if you have legal assistance on your insurance I would consider contacting them too if your insurer isn't helpful.

Given the extremes of wet/dry/hot/cold weather we've had over the past several years I would expect that to have had far more effect than even a very established Buddleia.

mrsS_2

Our house is on clay.   We had to have 1.5m foundations for our extension in 2001 that was one storey and 2m where it was 2 storey Our neighbours had to have 2m when they did their recent  1 storey one.   0.8m doesn’t seem very much even for a one storey especially if the trees and shrubs were already there. Could you ring your local building control at your council and ask what the current recommendations are?   Then at least you know if it is purely your shrubs or if the foundations are partially responsible ?

dunstonh

My structural survey in 2004 did not mention the extension as a problem; it did not mention the shrubs growing against the wall and it did not mention the oak tree at the bottom of the garden.

That is because it was your property it would have been focusing on. Not your neighbours.

Plus, shrubs in 2004 are likely to be very different to shrubs in 2021.  For example, someone in the 90s on our property put in a flowerbed alongside two barns.   A picture on the historic england website from some years later shows  a small colourful flowerbed.     Last year, we dug the flowerbed out as trees had got in there are some point and some the shrubs were getting under the brickwork.   We dug down and the damage underground requires over hundred new bricks and repointing.   They had also damaged the field drainage allowing it to build up and cause some movement.    

They are perfectly ordinary shrubs - buddleia, mock orange and forsythia, myrtle - not the ones I think of as dangerous and they have been there since before 2004. 

So, it is likely that they are involved in root damage then.  

The report suggests regular pruning to maintain the tree's height. 

In general, if you have trees on your land, you need regular pruning.   Its not particularly expensive to do but you do have a responsibility.   We have an Oak and and Ash within 10m of the building and the recommendation was to leave it as it was mature and the ground has settled with it being in place.    More damage would be caused by removing it.

I resent the fact that the whole liability for the problem is being unloaded onto me, with no consideration of the possibility that poor construction of the extension may be a contributing factor.

Just because you have involved your insurance, doesn't mean they will accept the liability.  

The repot indicates the extension's foundations are 0.8m and we are on very shrinkable clay.

Your thread title says subsidence.  Yet what you describe sounds more like movement.    Our house has constant movement as its on clay and every hot summer you can hear the pings when in bed at night.   Its all pretty routine and there isn't a house in our area that doesn't suffer the same.      Movement is much more understood nowadays and not anywhere near as scary as subsidence. 

Do you know the rating the structural engineer gave for the movement?   Building Research Establishment Digest No. 251 is categories are used by structural engineers and anything at 2 or below is considered cosmetic.   Insurance companies don't normally pay out on that as its routine maintenance. 

theoretica

So these technical people have said it unlikely the shrubs are the dominant cause?  Seems to me that starting from whatever is likely to be the dominant cause would be more effective.

procleon

Thank you for all your comments. I do appreciate the time you took to explore this problem with me. I think the future looks bleak for the maintenance of large shrubs in my garden! And also for my savings!

TELLIT01

procleon said:

Thank you for all your comments. I do appreciate the time you took to explore this problem with me. I think the future looks bleak for the maintenance of large shrubs in my garden! And also for my savings!

I don't understand why you say that at this stage.  The technical survey has said that it's unlikely the shrubs are the dominant cause so I would suspect any liability to you would be minimal.

Aretnap

Also you have home insurance to cover any liabilities that you do have. So even in the worst case scenario, you're looking at paying your excess and having a slightly higher premium next year (and having fewer shrubs). Your savings ought to be mostly OK. 

eddddy

procleon said:

Thank you for all your comments. I do appreciate the time you took to explore this problem with me. I think the future looks bleak for the maintenance of large shrubs in my garden! And also for my savings!

It's unlikely that you will have any liability for the current damage, because it doesn't sound like you've done anything negligent.

(I guess somebody might argue that not pruning the shrubs was negligent, but I guess your neighbour could see the shrubs from the road and never asked you to prune them - which would make them equally negligent.)

But now that a professional arborist has put you "on notice" that your shrubs are causing damage, you might well be negligent if you do nothing about it, so you might be liable for future damage.  i.e. You now need to deal with the shrubs.



If you disagree with the arborist's opinion, you could hire your own arborist and/or structural engineer who might have different opinions.

But if, for example, you do nothing on the advice of your own arborist and/or structural engineer, it might be very messy if more damage occurs in the future.

Thrugelmir

Leave the matter for your insurers to resolve. They'll investigate any claims made not simply accept the technical report per se. No need to panic.