drain relining

Does anyone have experience with drain relining? Was it OK? Did rodding damage it aftrerwards?

Our gable wall is moving slowly down and out and the likely cause is that the foul drain is leaking. The house is victorian so the wall footings are shallow. The drain runs parallel to the wall about 1 metre down and about 1 metre away but gradually gets closer and eventually bends and passes under the wall. The drain is the usual cermaic clazed clay sections with mortar/sand at the joints (125mm ID I think). By the time it reaches our house it carries the output of

4 houses.

"Lanes for Drains" did the TV survey which showed three joints displaced 'moderately' and they propose that we locally patch them. They do this from inside the drain with a special 'pig' which holds the patch against the drain wall while the glue sets.

They can also reline the whole drain, although they did not propose this. It's about 12 metres long. This would cover all the joints.

Many thanks for any comments anyone cares to make.

Robert

Reply to
RobertL
Loading thread data ...

There's a private sewer which runs across several of my neighbours' back gardens, and joins into a public sewer under my garden. A few years ago, the private sewer was always getting blocked because some of the joints had settled and come apart. After excavating to repair the worst problems, the powers that be [at the expense of the houses served by this sewer - thankfully not mine!] lined the whole thing - and it has been fine ever since. As far as I know, it hasn't neeeded rodding since this was done - so I can't comment how it would stand up to that.

However, my understanding is that the lining is pretty strong. It starts off like a large inside-out epoxy-coated stocking which is unrolled (if that's the right word) into the pipe using compressed air. When the epoxy cures, it leaves the equivalent of a strong plastic tube inside the original pipe.

Reply to
Roger Mills

Should work. But my instinct is to lift the lot and replace with plastic.

But are you sure the drains are the cause? On most soils wetness makes them expand, leading to heave, not subsidence.

Far more likely that tree roots are sucking the water out and causing the movement.

In any case get professional advice from structural engineers before doing anything: its cheap, and insurance companies will believe them, not us here.

You will probably have to underpin the wall, which is not cheap, (£1000 a meter) and will require deep trenching down the wall side. The drains can be sorted properly at the same time at very little extra cost.

This SHOULD be covered by insurance.

Stage one is to get structural engineers in. They will probably take soil samples and see what's causing the problem. My niece has a similar situation: Underpinning was required and some drastic willow tree pruning and root truncation. The new foundations go below any future tree root levels.

Your drains however, may not. They might need encasing in concrete,. But that's what structural engineers are for.

Then you will need to contact your insurance company: The engineers report will be what you need to force them to pay for remedial work AND force them to reinsure you afterwards. The whole job has to be signed off by the building inspectors and the engineers and the insurance company follows along. Or you wont ever be able to get insurance again.

Please do not attempt work at your own cost and without an engineers report. You could get refused insurance on the grounds the property is suffering from subsidence.

You MUST get a report. It will be a few hundred, and will ultimately be paid for by insurance if you decide what it says warrants containing the insurers, after all.

And believe me, they are going to give you an answer that is not only on the post, backed up by years of experience, but also usable in legal cases against builders and insurance companies. All we can do from here is make educated guesses. That carry no weight with anyone but ourselves.

Walls should not move even WITH leaky drains.

Get expert advice ASAP. and pay for it.

Reply to
The Natural Philosopher

Salt glaze is rigid, so if theres any future movement it would come apart at the joints again. Laying new plastic would much reduce that risk, and it could be laid in a somewhat more convenient position.

The subsidence may significantly complicate things. How much movement and do you want it to be insurable are relevant questions.

NT

Reply to
NT

I would say they are the primary problems, and that the cracked pipes are mere symptoms along with the wall, of a deeper underlying (sic!) problem that needs professional assessment.

Reply to
The Natural Philosopher

We really dont know, it can happen either way. Getting a qualified professional in sounds like a good idea, but having dealt with them on such matters I cant say I'm very convinced. But if one knows nothing about such matters, its probably the best option.

NT

Reply to
NT

In message , NT writes

Two points on subsidence in sandy soil. Yes, damaged drains can cause problems with nearby foundations. I have direct experience at a house in Cambridgeshire.

Also, some years ago, I discovered that house construction in the Black Forest (Germany?) is preceded by dumping large quantities of water into the soil to *wash out the fines*. Quite where this gem originated is beyond my few remaining active brain cells:-)

regards

Reply to
Tim Lamb

Thank you all for your comments. The house is, in fact, in Cambridge. We did have a structural survey before we bought it and the possibility of the drain causing problems was noted. the drai ncamera survey showed some moderate dislocations but nothing terrible and nothing collapsed. We later brought in a structural engineer to advise on some other work in teh house. He was clear that no more weight should be added to that wall (it wasn't).

We will probably get the structural engineer back again to advise us and I expect him to advise relining the drain and seeing if that stops the movement. i wanted to get a feel about whether people have gorror stories about such operations.

To dig up and relay the drain would be a big operation; The passageway between houses where the drain runs is about 2m wide so it would involve digging near the foundations of our house and the next one both of which are 110 years old. A 'keyhole surgery' apporach would be best if it would work.

thanks again for your help people.

Robert

Reply to
RobertL

That's symptomatic of underpinning work anyway.

Its mostly hand dug.

I didn't comment on te lining, because others did: it works pretty well. My worry was you might be looking at the wrong problem.

I assume you are using Firebrace..get them back in and be guided..top notch boys IMHO.

Reply to
The Natural Philosopher

A word of warning. A 'keyhole surgery' approach from inside the pipe run may sound the best but lining the pipe doesn't address what other damage the leaking joints may have done.

Any leaking joint in vitrified clay, or any other kind of sectional pipe, will not only lose water into the surrounding ground, but it the leaking water will also bring in some of the ground from around the pipe. Cleaning out the pipe and relining it will render it useful again as a drain, but it won't address the problem of voids in the ground that may have been caused by the leakage.

These voids can be surprisingly large, and if your house has shallow foundations they may well have been undermined. If you only line the pipe, you will never know, but the future may bring structural problems that may dwarf your current troubles with the pipe.

The video survey that has been done will have identified precisely where the leaking joints are located along the pipe run. I would strongly advise that you should excavate the pipe at these points and fill any voids around the pipe. These voids may be surprisingly large because the pipe joints may have been leaking for years.

You should not worry unduly about disturbing your foundations, or your neighbour's. The weight of the structure of the building is transmitted into the ground from the base (underside) of the footings and not from the sides. So you can excavate down to the level of the base of the footings without affecting anything at all.

Below that level, the load is assumed to be spread out at 45 degrees each side from the base of the footings. If you need to excavate below that level, you need to stay out of that 45 degree zone. But if you are digging only a small hole down to the pipe, you should be able to infringe on the 45 degrees locally in order to do that. Your structural engineer will be the best person to advise you on the details of this and you should follow his/her advice to the letter.

Your neighbours will also have an interest, because as the owner of the pipe you could be held responsible for any damage caused to the neighbours' property as a result of any unfilled voids caused by the leaking pipe. So it is in both your and your neighbours' interest to ensure that any remedial work addresses not only the leaking pipe, but any voids in the ground that the leakage may have caused.

Reply to
Bruce

mmmm this is a waste run not a high pressure water main.....

due to the nature of the pipe contents I wouldn't expect humungous (if any) voids to be found as there's no pressure in the pipe. Maybe some seepage into the soil/subsoil but that depends what the soil/subsoil is, density etc.

IME misaligned joints/sections can "self seal" with waste matter.

Spose the question wrt "voids" is how long have joints been misaligned, how badly and how frequently are they disturbed to leak again after self sealing?

Only way to find out would be to dig up one of the alleged leaky joints and see/smell how bad it really is.

NB any of Tony's "voids" will be full - of sewage...

Jim K

Reply to
Jim K

yes indeed. I have used Firebrace several times and always find them excellent and will contact them again abotu this. there are no trees nearby so it is most likely that the movement is from drains washing the fine sediments out, slowly. I feel it is worth lining the drain anyway so it's not money down the drain (ha ha).

Robert

Reply to
RobertL

Ah yes, but the footings are shallower than the drain and the drain passes under the wall. At the front of the house the drain is about 1 metre from the wall running roughly parallel to it. it gets closer as you go back and at 6 metres further back is passes under the wall and curves round to go next door (under the back kitchen of my house).

To excavate the drain at the identified bad joints would involve digging right under the wall.

R
Reply to
RobertL

So you know that the bad joints are in the most critical possible area for washout, directly under the foundations of your house.

And you are going to ignore the problem, apart from putting in a flimsy lining that in no way addresses the washout problem.

Have you notified the insurer of your structure and your mortgage lender of your proposed course of action? If not, and there are any problems in future, you are likely to find yourself uninsured.

Reply to
Bruce

....sayeth Tony the alleged retired surveyor, no doubt remembering the "jobs for the boys" training he was indoctrinated by...

IMHO if you tell insurers they'll GUARANTEE not to insure you possibly by hiking the premiums/excesses so that you are potentially uninsurable..

How about do the relining "repair" and see what happens - if things get worse re walls etc THEN involve insurance (and keep shtum about the relining.....)

T'would be good to have a way of monitoring things over months (real surveyors put little target things on the walls and periodically measure their positions - you got a laser measurer thingy?)

Can we take it the back kitchen with the pipe under the foundations was (at some time) an extension of the original building? is it single or more storeys? digging and probing/looking for tony's "underground sewage filled caverns" wouldn't phase me (or a decent builder) as much if only a single storey above... The hole(s) needn't be big. How deep is the drain at the back of your kitchen?? (perhaps there a drain cover you can lift and peer into to estimate depth)

Jim K

Reply to
Jim K

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.