Possible subsidence caused by leaking soil pipe/water mains.

[lenny]

Bare with me as I tell of my dilemma any help will be very much appreciated.

Hi first of all could anyone recommend a structural engineer based in Manchester/North West to look at and give advice on the problem below please?

I moved into a Victorian house with a 30 year old extended kitchen. After about a year there were some sunken flags at the side if the extension where there is also a drain and soil pipe. These enter the ground where the extension meets the old build.

I had the soil pipe fixed as it looked like some one had made a hole in it to rod it and re-levelled the flags.

About a year later the drain cracked at the side of the gulley and water has been running down into the ground for about a year and the flags have sunken again. I also noticed small cracks running up the wall of the old build about a 2 feet away from where it meets the extension.

I recently found out from a neighbour that just before I moved in there was a mains water leak under my extension, as there is an old lead water main that feeds the neighbours as well as the soil pipe running along the back. It looks like the previous owner had the leak fixed by digging under the foundations.

I was hoping to fix the problem my self by either smashing thru the kitchen concrete kitchen floor or digging along side the building and pouring in concrete. Has anyone any suggestions about which route to go down please?

Also inside there is plaster crumbling along the skirting which would suggest damp coming thru the floor.

Oh yeah I also recently moved Insurers just to make things worse but from what I have read the Insurance route is not necessarily the best route.

Any help/advice will be greatly received as I'm pretty stressed out about the whole situation!

Cheers

Lenny.

[Phil L]

This doesn't sound like the house is sinking, but that the extension has dropped, pulling the house with it, nothing to wory about though, providing the cause of the sinking has been seen to.

How far under? - if it was just a short dig under one sdmall part of the extension there should be no trouble, however if he has excavated one elevation of the extension and not backfilled with something substansial like lean mix concrete, or at the very least compacted hardcore, there could be problems ahead.

you are talking about underpinning here, and it's not something to enter into lightly, firstly, if the extension isn't built on solid ground and you add even more weight to it by doing the underpinning, you could make matters worse because it will sink faster.

You may need a new floor, back in the 70's, cowboy builders were everywhere and building regs were nowhere near as stringent as they are today, meaning there's very likely no membrane between your floor and the substrate, but this is the least of your worries.

There are a few things you can check yourself before you start throwing money around, and don't panic about it falling down - it's been there 30 odd years now, it's not likely to collapse in the next few decades, firstly, are there any internal cracks where the extension meets the house? - if there are, they will be worse higher up, IE where the uppermost 'new' brickwork meets the existing brickwork. Secondly, does the extension look like it's leaning? - if you can get far enough back, have a butchers and see if it looks pissed (don't sight along the roof or gutter line, these may be miles out anyway)

If it were my house, the first thing I would do would be to uncover the foundations of the extension and see what the depth is, also the depth of concrete under the brickwork, and most importantly, what the concrete was poured onto, ideally it should be clay or compacted sand and should be at least 1m from ground level to the bottom of the concrete, more is better.

[calums]

Lenny I agree with all Phil's comments. Especially a trial dig to see what the existing founds are like.

I would also put some 'tell tails' on to the wall where the cracks are so that you can monitor if there is any further movement, and if so how much. They are very simple to make. Just get 2 rigid strips of plastic one 40mm wider than the other (cut up a square tupperware box or something similar) and attach one horizontally to one side of the crack using 2 screws, and do the same on the other side of the crack. Allow the 2 strips to overlap each other. Now using a permanent marker draw a straight continous line horizontally between the strips. Now do another line vertically again where the 2 strips overlap.

If in a few months time if these lines are still all lined up then the property has settled. If the lines are broken then at least you know how much movement is taking place.

Leave the tell tails in for a year or 2 even if no movement has taken place, just for your own piece of mind.

I would also check that your gutter down pipes are all in sound condition once they go under ground, as this can also cause problems.

Hope this helps

Calum Sabey (NewArk Traditional Kitchens 01556 690544)

[Lobster]

I'd wholeheartedly reccommend

if they are near enough to you David

[Hugo Nebula]

On Fri, 09 Feb 2007 16:38:07 GMT, a particular chimpanzee named "Phil L" randomly hit the keyboard and produced:

In Manchester, 750mm into clay [*] or 450mm into sand or similar is acceptable. [*] Except if there are any trees within several metres.

The other thing to consider is the depth of the drain and water pipes. To the OP: you say the water pipe had to be replaced 'below the foundations'? Water pipes aren't normally buried very deep, so this would make me concerned that the footings are shallow, and whether they are they undermined by the drains as well.

I agree with Phil that the first thing you have to do is a trial hole to check the level of your foundations, and also check the levels and the condition of the drains.

If you have to underpin the extension or replace the drains you may have to get your insurance company involved to cover the costs. Beware if you do; make sure you get on well with your current insurers and that they will provide cover to anyone, because if you get them to even investigate whether there is settlement (irrespective of whether they then pay out for remedial work), then some other companies may not even consider you or any future owners.

[lenny]

Thanks guys for the advice I'm going to have a dig around in the next week or so I will let you know of my findings!

Cheers

Lenny