Clay Soil Pipe cracKen

[Mark R]

Hi all.
I’m in the process of clearing my old patio and under a slab and builders sand I found the soil pipe from our bathrooms. After cleaning the soil away I found that it is cracked. It’s in a very awkward spot as it’s comes out of the house at 45 degrees and to replace would mean removing part of the wall. Is there an alternative to this? Some kind of sealant? It’s not leaking when we pull the flush.
I will be pouring concrete over it to build my sub base but would like to now if it’s ok to do without it being a problem later.

 

[vxxbcks]

Can be lined probably

 

[Hugh Jaleak]

I think the main reason it has cracked in the first place is movement, it may do more harm than good concreting it in now. What is the floor made from inside?

 

[Mark R]

I think the main reason it has cracked in the first place is movement, it may do more harm than good concreting it in now. What is the floor made from inside?

The house was built in 1979 and has a concrete floor. There are a lot of trees surrounding the rear of those house and there has been some movement but nothing serious.

 

[Hugh Jaleak]

It wouldn't take much movement to crack that, especially if there is insufficient flexibility in the pipework. It looks like is encased in concrete just after it leaves the hose, if it's also embedded in a concrete floor with inadequate expansion provision, then the slightest movement will crack it. (You can see where the wall has cracked alongside the drain, so there has been some movement in the past. A clay soil could also be part of the issue.

I would be seriously concerned about adding any more concrete to the situation, the pipe needs to be able to move, otherwise I fear it may collapse, leaving you with a far bigger problem than you have already. Patch Lining that section may be an option, provided the liner will flex a little. I would then wrap the pipe in fibreglass insulation before putting any concrete down, to give the pipe some space to move in future.

 

[Mark R]

It wouldn't take much movement to crack that, especially if there is insufficient flexibility in the pipework. It looks like is encased in concrete just after it leaves the hose, if it's also embedded in a concrete floor with inadequate expansion provision, then the slightest movement will crack it. (You can see where the wall has cracked alongside the drain, so there has been some movement in the past. A clay soil could also be part of the issue.

I would be seriously concerned about adding any more concrete to the situation, the pipe needs to be able to move, otherwise I fear it may collapse, leaving you with a far bigger problem than you have already. Patch Lining that section may be an option, provided the liner will flex a little. I would then wrap the pipe in fibreglass insulation before putting any concrete down, to give the pipe some space to move in future.

Thanks Hugh. The pipe enters the house and immediately bends up towards the first floor so I don’t think it’s embedded in the concrete ground floor. It’s located inside a right-angled plasterboard box (I don’t know how you would call it).

 

[Hugh Jaleak]

That's handy, now there may be an alternative method, if not a little tricky.

If you can carefully dig away around the pipe where it goes under the house, you should be able to find a plastic 'Collar' where the broken pipe joins the rest bend at the bottom of that stack. Ideally if you can get to that, it may be possible to remove the broken section from that collar and replace. If you put a flexible coupling immediately outside to join the new section to the old, that will not only help with any future movement, but gives you a watertight drain. Any idea where it goes to downstream of the house?

If unsure, I'd engage a reputable Building or someone who understands drains. What I wouldn't do is try and bodge it now, as it may come back to bite you later.

 

[Mark R]

Good to know. The pipe leads to a branch channel in a manhole which is just over a foot away from the pipe. This has an outlet to a 3m pipe leading to another inspection chamber where it leads to a drain going down the side of the house to the main sewer in the street. The manhole is pretty much the same as the illustration I’m attaching.

 

[Hugh Jaleak]

If you can couple onto a decent section of pipe before the manhole, then it should be fine, they key will be allowing for movement. 2 large lumps of masonry with a short run of clay drain between them, and no room for movement, is never a good recipe.