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.
Four years ago it cost a neighbour £4k to drill and fill sixteen piles of 25 feet deep. As I assume this situation isn't so bad (this was on an ex-marsh) you should be able to interpolate down.
Walking away is the only rational option. It will be impossible to insure the property and the costs of a properly designed scheme would certainly escalate way beyond your estimate.
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.
Can you actually prvide evidence for that? I have seen underpinnig done roun here and it was certaily not a total ecsalation such as you describe. Lbour intensive, messy, and a right royal pain, but it took only about 6 weeks of three blokes to do a similar section.
At a garnd a weekm thats 18 grand...
..walking away is not an option here, unless it truly is 'cheaper to demolish and start over'...which would be about 100k estimated.
You really, really, *really* should make sure you can get buildings insurance on this property. If you can't, even should you be foolish enough to buy it, you won't be able to sell it, so it will be valueless.
BTW, and this is from personal, current, experience, underpinning is no longer flavour of the month. We have a problem due to adjacent trees (mainly a mature oak about 20 feet from the house) and the insurers want all of them cut down. When I mentioned underpinning, both my structural engineer and the insurer's structural engineer said "it doesn't work".
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.. .
Its insured right now, and there may be a claim on it by the current owners.
Its not for residential purposes BTW. That's why its had to walk away. Its required for business purposes and has the requisite planning for that type of activity, and is in a perfect location for it - with no suitable alternatives anywhere remotely near.
I totally agree that an uninsurable property is worth only plot value less clearance costs.
Its not as bad as you think - there are signs of cracks and maybe up to an inch of sink in the worst place. Since estimated 1970. I don't think its dangerous, or will fall down, but fit for purpose means stopping the process and making good the existing damage.
Costs of fixing it to a level that satisfies BCO and insurance companies is the issue.
One assumes contacting the correct type of structural engineers, and getting a report and recommendation and implementing it is what will have that effect.
Well it does, and it doesn't.
As I said before my house had tree problems. I being reluctant to remove them, the engineers simply said 'well we well go down soil sample wise to a level at which the tree roots are not present in any form, and then some, and build a concrete wall that will stop fresh roots dead in their tracks' essentially. They also insisted on a raised concrete floor to allow the already shrunk earth to expand without upsetting the floor levels, which is a serious problem if you simply cut the tree down - soil moisture returns, expansion happens and the building gets pushed up again.
The essence of underpoinning or piling - as I understand it - is to get the solid base of the fondations down to a level with stable charcteristics, and let the soil above move as it will, without that affecting the structural integrity of the house.
I am intersted in the piling type methods - that was given to me as a potentially cheaper way in my case, but that would have consisted of building a sort of viaduct of vertical concrete posts, with beams laid across othe top, to form the foundations.
I cannot see how it cold be done as a remedial method.
If anyone knows, please share.
Indeed.That is an option as well in the current case, for a couple of nasty conifers.
But the main protagonist is a rather nice weeping willow some 10 meters from the worst corner. I am fond of willows, though they have a reputation for this kind of thuggery.
What might be very simple and totally possible is to trench down a couple of meters about a foot from the footings, and fill that with concrete. That would cut the roots there, and stop any further penetration to the footings area. I believe willow roots are pretty shallow.
Of course doing that UNDER the footings and backfilling with concrete and mortar would be ideal..
The arborist who came to look at our situation said that the rule of thumb is 1.5 times the diameter of the drip line for oaks and twice for willows, although the rule I've heard for willows is that if you can see them from an upstairs windows, they're too close. Pity, 'cos I like willows.
I would add that you should contact the current insurers and check whether they are willing to insure any future buyer of the property to ensure continuity of cover by the same insurer. I always thought there was an 'unwritten rule' amongst insurance companies that they would always do this; however when I recently looked into buying a property which had been underpinned (properly, with all necesary guarantees etc) the current insurers said 'no'. Which rang alarm bells. A few enquiries via brokers produced either responses of 'not-with-a-bargepole' or 4-figure annual premiums (where about 150GBP would be the norm).
The message from The Natural Philosopher contains these words:
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Would the current insurer have an obligation to continue to offer insurance on the property?
That seems a bit extreme. If the property doesn't get any worse then not insuring might be financially beneficial. Total loss claims are very rare and those from subsidence even rarer. I once tried to shift my house insurance but putative new insurer wouldn't cover it for subsidence on the grounds that it was too old and decrepit with shallow to nonexistent foundations and, to add insult to injury, refused to reduce the premium to take account of the lack of cover for subsidence.
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ISTR reading somewhere that piles are inserted both sides of the walls and linked at the base of the existing foundation. However that was a long time ago and memory fades ....
Its the ideal place to run a specialised business from, has planning permission for it, and is in every other way totally ideal for the job. There is nothing or 15 miles - the catchment area of that business - remotely as good.
No. Building (in fact, all) insurance is there to make money for the share holders. They REALLY don't like paying out. Give them 1/2 an excuse and you're on your own!!
Good advice. I will relay that to the prospective purchaser.
However in terms of 4 figure insurance, well 1000 quid a year more is - at say 5%, £20,000 equivalent on purchase price. So since this is a commercial buy, simply another factor in the cost benefit equation. Knock 20 grand off the asking, and it comes to the same in the end.
I reckon the site alone is worth about 150k, and the current 'guide price' is 300, but we suspect that it might be worth offering 265...
My 'demolish and rebuild' costs show that it could be reproduced in good order as a 4-5 bedroom house for around 450k including purchase, so in the final analysis, if the property is cheap enough its not a losing proposition.
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