300 year old oak and subsidence

[Mark Richardson]

I have a 300 year old oak tree at the bottom of our garden, which is in excellent health. Our neighbour's insurers have applied to have the tree felled, as they have had a report suggesting that the tree has caused the subsidence, as it has dried out the clay soil. A significant number of local residents objected to the application and the local Council have now issued a preliminary TPO and we are now in the 28 day period where further submissions can be made to the Council, before they decide whether to confirm the TPO.

The Council tree officer has valued the tree and will have to convince councillors that the tree is of sufficient value for them to confirm the TPO and risk having to contribute to the costs of alternative solutions. The tree officer fully expects the insurers to object to the TPO.

This is all new to me, so can anyone help me with the following questions -

1.     HEAVE. The neighbour lives in a semi detached house and the occupants of the other half of the house faced the same issue of cracks when they moved in in 2011. Their insurers ended up concluding that the risk of heave (the oldest houses around the tree were built around 1900, so well after the tree was here) meant that they had to find an alternative to felling the tree. They ended up putting in a 2.5m deep root barrier, which appears to have largely dealt with the subsidence problem. There are 4 1900 era houses close to the tree and the one making the claim is the only one having subsidence issues. None of the houses had any foundations when they were built, but many of the houses, including ours, have had extensions since, which have included some proper foundations. The house making the claim has never had an extension and therefore still does not have any foundations.

My question is the Council do not seem to be worried about the risk of heave and the insurer’s report simply says “Heave is not a concern”. Indeed the Council say any submissions we make during the consultation period should address the amenity value of the tree and that there is no point in talking about heave. How can this be right when all of use are concerned about the risk of heave?

2.     MEASUREMENT OF MOVEMENT. The monitoring report shows that the largest movement in cracks was 8m, measured between February and August 2020. Is measuring just between a very wet February and a very dry August considered best practice?

3.     DRAINAGE INVESTIGATION. The drainage investigation performed seems to have identified some damage to pipework that needs to be repaired. However, the acoustic test to the water main suggested that there weren’t all leaks to that. How is it possible to establish whether any of the leaks involved might be encouraged the root growth from the oak and thereby contributing significantly to the problem?

Many thanks in anticipation! Mark

[monkeybusiness]

What do your insurers have to say about the issue (most importantly the potential for heave to your property following removal)? 

[Khriss]

I would view it as a healthy veteran Oak of substantial value, ecologically and historically ( from report)  the structural inadequacy of the properties have an engineering solution ( underpinning,  root barrier, pipe sleeving , etc ) confirm TPO and let insurers and utility  pay.   K

[Mark Richardson]

Thanks Khriss. How confident can I be that the TPO will be confirmed? The Council tree officer does seem keen to protect the tree, but she needs to convince the Councillors to accept the financial cost of contributing to the remedial work costs.

[Mark Richardson]

My insurers seem relaxed about heave, I think on the basis that my neighbour's insurers will be in the frame for the costs of fixing any heave issues.

[eggsarascal]

17 minutes ago, Khriss said:

I would view it as a healthy veteran Oak of substantial value, ecologically and historically ( from report)  the structural inadequacy of the properties have an engineering solution ( underpinning,  root barrier, pipe sleeving , etc ) confirm TPO and let insurers and utility  pay.   K

What will utility be paying for?

[Khriss]

1 hour ago, Mark Richardson said:

Thanks Khriss. How confident can I be that the TPO will be confirmed? The Council tree officer does seem keen to protect the tree, but she needs to convince the Councillors to accept the financial cost of contributing to the remedial work costs.

Sounds like you answered yr own question- the TO sounds a good type, I would err over its actual age but if they confirm it's predating the houses, it's a cracking tree to retain. Possibly flag up its value in yr community / social media group and promote retention. House insurance is there to pay for shortcomings in build and aging, without seeing the soil data and a site visit I couldn't advise on potential heave and it's consequences but the insurers job is to get an expert it to solve the issue with the buildings. K

Edited August 27, 2020 by Khriss
( I would put today's wages on Bat occupancy or forage use... hint hint ? )