Ash tree removal - risk of ground heave?

[Claire Bennett]

Hi,

 

I'm new to this forum and looking for a bit of guidance! 

 

Our neighbour's insurers have asked us to remove a large ash tree due to it being the cause of subsidence in their conservatory. We don't want to get into arguments about whether it is the cause or not, or how well their conservatory was built, so to keep the peace we'll get the tree removed and have had quotes already. We were only advised in December, so we are moving things along as quickly as possible.

 

We are just nervous about ground heave, and this is has so far stopped us booking the appointment to have the tree removed. The tree is on heavy clay (Cambridge) and next to a brook, which fills to around 3 feet in winter with field water run off. The garden slopes down away from the house so we are thinking this may reduce the risk of heave? 

 

I've attached some photos so you can get an idea of the size of the tree and proximity to the house, along with some excerpts from the insurers report re soil plasticity. 

 

Any help or guidance would be really appreciated We are just not sure where to turn to for guidance as our arborist doesn't want to get involved!

[Vedhoggar]

You could try the Arboricultural Association website (www.trees.org.uk), go to 'Find a Professional' then 'Find a Registered Consultant'. 

 

[Jon Heuch]

Claire

Heave is a complex issue that is difficult to be certain of even if I had visited your property and had all the information available. Luckily it is not particularly common so that is some reassurance.

If your neighbour's insurance wants you to remove your tree then you can be reasonably assured that they will cover the risk of heave to their property.

I can't see if your property is detached or semi detached? Has movement in their property affected  your property at all? Has there ever been any movement in your property? Clearly, the usefulness of that information depends on how long you have lived there....

 

The best advice I can give is make sure you have the standard buildings insurance that includes the standard section on heave, landslip and subsidence. It will typically have an excess of £1000. This, by itself, will cover the "risk" arising from the removal of your tree. You could spend money on time trying to ascertain what risk of heave there is but in reality that risk doesn't not act a defence to not removing the tree if indeed it has been shown to be the cause of movement.

 

The other aspect to an ash tree is that it may succumb to ash dieback and die; a similar "heave" risk applies then, so you may not be able to avoid it. I see the tree has been pruned back before and regrown.

 

The above provides some insight into the situation but doesn't provide a comprehensive analysis.

[benedmonds]

I agree with Jon that it is a complex issue, but this is classic blame the tree first.  I am not an engineer but land slipping down the slope is far more likely to be the cause of the subsidence IMO. 

Have they provided crack monitoring and root id from underneath the conservatory? 

 

I would be surprised if the tree has caused the subsidence and very surprised if removing it would cause heave. Plus it is an ash tree that is quite likely to die from ADB in the next few years so you are probably going to have to remove it and cope with any ground movement.

 

There is no cost effective method of preventing any potential heave and you would just repair the damage, so I would just crack on and remove the tree. Having insurance would be prudent but I don't think there is a benefit of paying for consultants who could tell you if the risk is high or low.    

  

Edited January 22 by benedmonds
typo

[doobin]

There's just absoloutely no way that tree is causing subsidence- look at the height difference FFS! And being right next to a brook, well there's the water table. It's not got to go far for water and it's not a particularly thirsty tree either.

[Paul Cleaver]

Ah the old conservatory issue.

 

Edited January 22 by Paul Cleaver

[Canal Navvy]

58 minutes ago, Paul Cleaver said:

Ah the old conservatory issue.

 

 

Sits back to enjoy the candyfloss 

[Steven P]

I'd ask their insurers to write an indemnity for your loss of the tree in the case that further cracks occur after the tree is removed.

[daveatdave]

i am far from been an expert on these things but i think the tree has been there before the houses were built never mind the conservatory and they appears to be a few smaller trees and large shrubs closer than your tree. is there a TPO on the tree? as mentioned before it will more than likely serum to ash dieback if the Nabours insurance will pay to have it removed get it done it might save you money. 

[Claire Bennett]

Hi everyone,

 

Thanks so much for your responses, they have been really helpful!

 

The insurers are totally adamant that our tree is the issue, and we are adamant that it is not and the conservatory is falling apart due to a myriad of other issues/ reasons. 

 

However, given that we don't want the stress (or even more costs!) of a legal battle we are reluctantly having the tree felled.

 

Your comments around Ash dieback actually make us feel better about it, and that it would probably have to be done in the future anyway... plus the point around the cost of hiring consultants to assess the risk probably isn't worth it.

 

I'll make sure I check our insurance docs for heave coverage though, that's a good shout.

 

Sad to lose the tree for no real reason, but we'll crack on and get it felled and the neighbours conservatory will still continue to suffer from subsidence (or basically continue to fall apart as it's 30 years old).. but at least they can't point the finger at us anymore 🙄

 

Thanks again