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The Natural Philosopher
 
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Andrew Mawson wrote:

"The Natural Philosopher" wrote in message
...

Been looking at a poetntial buy for a friend, and it looks like part


of

it - a rather shoddy 70's extension - has a bit of a subsidence


problem.

Possibly due to a couple of trees nearby - one a willow.

IF - and pending investigation - it needs underpinning, has anyone


any

ball park estimates for costs?

Walking away from the buy is not in the frame really - its more


about

price adjustment to reflect the condition.


Relevant information is :-

- access for machinery is no problem
- it's on clay soil, and wettish clay (quite low lying)
- about 20 meters of wall might need treatment.
- my guess is there are minimal foundations - one or two feet at the
very most.

My wet finger guesstimate was a grand a meter absolute tops,


thinking

that it could hardly take more than a week for a bloke with a shovel


and

a cement mixer to dig out a bit and fill it with concrete. At 10


quid a

day max.

It could be possible to take up the internal floors as well if this


is

desirable, but that would be far more of a job.

I am after any information anyone has on techniques that are


employed to

do this job, and any real world data that is better than my wet


finger

guesstimates.

In fact any information on mild subsidence and its remedy would be


welcome.

I seem to recall a test case (?? in Wimbeldon??) where if the work was
done on the extension when it was built under normal planning and
building regs control the local authority picked up liability as they
had charged for inspections. It was following that case that local
authoities increased the required depths of foundations markedly.


I would not be surprised.

When I pulled down my old house, which had foundations of a massive 6
inches, and was showing mild signs of subsidence due to trees and clay,
in one corner they made me go down 2.2 meters...for the new ones..

But these days, with a digger and simply pouring concrete,the
opportunity cost on a new property is not that great, to add massive
foundations.

I often wondered what 'Time Team 3000' woild have to say about it in due
course..
..

AWEM