UKTC Archive

RE: Subsidence where foundations less than 300mm deep

Subject: RE: Subsidence where foundations less than 300mm deep
From: Atkinson, Joe
Date: Sep 09 2020 08:06:47
I thoroughly recommend the AA course "Getting to grips..."

Vividly recall Dr Biddle opening with "trees can and DO cause subsidence".

He went on to offer several nuggets, including the point about climate.

Wayne - while the UK and US have similar soils and similar tree species, 
growing at similar rates and sizes, our climates are very different. UK 
climatic variations are mild (temperate, Atlantic, island), whereas US 
climate is continental. US sees much greater range of winter lows and summer 
highs, and background soil volume variations are considerably greater.

Meaning that, in the UK, I could build my house from rigid, modern materials 
(brick, steel, glass, concrete - as opposed to historic use of stone and 
wood) on relatively shallow foundations, and it should stand. In the US, many 
houses are built as a timber superstructure on a deeply founded cubic 
concrete basement, because it will move with the seasons (I'm thinking of my 
cousin in Minnesota - 5 months of winter with 5 feet of snow on the ground, a 
five-day "spring", then 6 months of summer with temperatures in the 80/90 
farenheit range, five-day fall, then bang! More winter...). Built in the 
1890s, and surrounded by huge oaks, it still stands on a basement footing. 
Little bit of timber superstructure movement just adds character!

2 anecdotes from my own experience:

As city Arb officer, fought tooth and nail to keep a plane in front of an 
Edwardian brick house with bay windows and a side extension. Fended off the 
initial claim. Head of Legal nervous. House was repaired, then owner's 
insurers asked if we would pre-emptively remove our plane, lest damage should 
reoccur, at which point our insurers advised Head of Legal to set aside a 
hefty sum as reserve in case of future claim - tree was removed forthwith, 
leaving a hole in a fabulous avenue. The tree gang found that someone had 
filled a decay column in our plane with concrete at some point. Amazing.

More recently, standing in as contract TO in Berkshire, a TPO Oak was 
suspected of contributing to damage. Owner had removed all woody vegetation 
on their property. House still moving, level monitoring showing differential 
movement, particularly where services entered the dwelling (bridge 
foundations over utility trenching). Quick glance at Google Earth (to help 
site visit logistics) showed yellow grass everywhere locally in drought 
summer of 2018. Uh-oh. Very big tree, 9m from side elevation, crown 
overhanging the eaves. Terrible shame, but not sensible to retain - as Jerry 
has said, the property value and our insurance system makes it hopeless - the 
'80s development should never have been allowed with the tree retained, IMO.

Cheers

-----Original Message-----
From: uktc-request@xxxxxx.tree-care.info <uktc-request@xxxxxx.tree-care.info> 
On Behalf Of Wayne Tyson
Sent: 08 September 2020 21:18
To: UK Tree Care <uktc@xxxxxx.tree-care.info>
Subject: Re: Subsidence where foundations less than 300mm deep

Lookit what I found! Very characteristically politely stated, but 
knowledgeably. However, it is not impossible to measure the rate of water 
absorption by clays.

https://www.youtube.com/watch?v=dTRdmt0BlVk

Unfortunately, I found the more senior gentleman somewhat difficult to 
understand, but Mr. Crilly was quite clear. In the absence of solid research 
to the contrary, I'm presently placing the tree-caused subsidence (actually 
shrinkage, in expansive clays) in the persistent myth category (back where I 
found it).

Wayne


On Tue, Sep 8, 2020 at 12:22 PM Bill Anderson < 
anderson.arb.original@xxxxxx.com> wrote:

I don't think Law comes into it Liam. It's insurance industry
practice, unless there's a dispute over who's tree it is that causes
the problem and who should have done something to prevent it. As far
as I can see if my tree causes my house to subside, the only person to
blame is the one that designed the foundations. Of course that person
might have said these foundations are OK but don't let your Mulberry
tree 5 metres away ever get to be more than 6 metres tall with a
commensurate spread, but as far as I'm aware foundation-designers
rarely say that. I'd agree entirely that growing a dirty great Oak
tree hard against a wall ought to be an obvious no-no, but building
something without foundations and then blaming a random nearby tree is just 
illogical.

And off-hand I bet the insurance industry spends more of our premiums
on keeping their execs in Porsches and BMWs than it does on subsidence
payouts!

Bill.


On Tue, 8 Sep 2020 at 19:47, Liam McKarry
<Liam.McKarry@xxxxxxxxxxx.gov.uk>
wrote:

Sorry Jerry I don’t agree - the cost of increased numbers of
insurance claims is met by premium prices going up; it’s a cost met by 
customers.

Liam McKarry
Arboricultural Officer (Planning)
01206 XXXXXX
________________________________
From: uktc-request@xxxxxx.tree-care.info <
uktc-request@xxxxxx.tree-care.info>
on behalf of Jerry Ross <trees@xxxxxxxxxx.co.uk>
Sent: Tuesday, September 8, 2020 7:34:27 PM
To: UK Tree Care <uktc@xxxxxx.tree-care.info>
Subject: Re: Subsidence where foundations less than 300mm deep

This message originated Externally. Do not click links or open
attachments
unless you recognise the sender, were expecting it and know that the
content is safe.

"we demonise the insurance industry for trying to minimise the cost
to their customer"


Delete 'customer'; substitute 'shareholder'.

From my mobile
On 8 September 2020 18:43:44 Liam McKarry <
Liam.McKarry@xxxxxxxxxxx.gov.uk>
wrote:

Bill,

It’s merely a statement of how things are as per case law.

Even if the foundation is not deep enough, in the absence of tree
roots would the damage occur is one of the first questions asked.
I’m unaware that anyone has ever successfully challenged it in law
and therefore, however illogical it is, we just have to deal with it.

Subsidence is a divisive subject that as an industry we get
ourselves
in
knots over (unnecessarily in my opinion) and have never really
understood
that at the bottom of this is usually a person who just wants
their
house
fixed and  (how much flak will I get for that one!)



Liam McKarry
Arboricultural Officer (Planning)
01206 XXXXXX
________________________________
From: uktc-request@xxxxxx.tree-care.info <
uktc-request@xxxxxx.tree-care.info>
on behalf of Bill Anderson <anderson.arb.original@xxxxxx.com>
Sent: Tuesday, September 8, 2020 6:18:40 PM
To: UK Tree Care <uktc@xxxxxx.tree-care.info>
Subject: Re: Subsidence where foundations less than 300mm deep

This message originated Externally. Do not click links or open
attachments
unless you recognise the sender, were expecting it and know that
the content is safe.

"Whether we like it or not inadequate foundations is rarely a good
defence
if the property is on a clay soil with a cyclical pattern of movement"

I don't see any logic in this statement Liam; why bother with
foundations
at all? If the foundation is not adequate for the soil type,
doesn't
meet
spec, (specification) it's not really fair to even call it a
foundation.
However if the foundation does meet the spec and still moves then
yes remove the tree, and hope that another one doesn't grow.
Notwithstanding
the fact that if the foundation meets spec and still the building
cracks
then the spec must have been wrong.

I'm not saying your quotation isn't an accurate summary of what
happens,
just that it's not really logical, and certainly not fair. Jerry
has
summed
it up really eloquently in my opinion.



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upon it, or forward, copy or show it to anyone; please notify the
sender, then permanently delete it and any attachments. Any views or
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those of Colchester Borough Council. Although the Council has taken
reasonable precautions to ensure there are no viruses in this email,
the Council cannot accept responsibility for any loss or damage
arising from this
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or attachments. The Council takes the management of personal data
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and it does this in compliance with data protection legislation. For
information about how personal data is used and stored, please go to
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