Repair to cracked clay waste pipe?

Discussion in 'Plumbers' Talk' started by Malcolm Douglas, Jul 5, 2018.

  1. Malcolm Douglas

    Malcolm Douglas New Member

    Hi all,
    I'm currently laying a patio and while digging I have discovered that my soil pipe is cracked at the collar where the downpipe connects with the underground pipe. There is no leaking when the toilet is flushed but this is probably because the crack is on the top. Is it possible to repair the crack without removing part of the pipe?
    Any help would be greatly appreciated image000000_20180704212306861.jpg

    Attached Files:

  2. KIAB

    KIAB Super Member

    It ideally needs to be replaced.

    Is stack pipe cast iron.

    Sometime you can cut out damage clay pipe with grinder & used a piece of plastic soil pipe with flex seal couplers to make a repair.
    But, in your case space is tight, plus you have that block of concrete around pipe, which things even more harder to access.
    Last edited: Jul 5, 2018
  3. KIAB

    KIAB Super Member

    Cut pipe on red lines, might need to might cut out larger section to give you some wiggle room.

    Last edited: Jul 5, 2018
  4. Malcolm Douglas

    Malcolm Douglas New Member

    Hi there, thanks for the reply, yes the stack is cast iron, so ideally I would have to dig back away from house and cut the pipe then put a join in? Is a repair to the crack itself not feasable? My hope was to excavate (carefully) around the whole collar around make sure the only crack was at the top and then fill/repair the crack and encase the joint in a suitable concrete or is this unsuitable? I dont want to take any chances as it's a soil pipe?
  5. KIAB

    KIAB Super Member

    Might be possible with GRP or some other suitable product, but I've found it then crack somewhere else in the pipe.
    Also digging out might also cause rest of pipe to break.
  6. ramseyman

    ramseyman Screwfix Select

    Best to cut it out as suggested. However if the concrete surrounding the cracked area is fairly crumbly you could try carefully chipping away with a lump hammer and half inch cold chisel, then make up a box and cast a small block around the pipe with a mix of 3 and 1 sharp sand to cement. Have done this successfully on occasion, but make sure the ‘joint’ is well supported/stabilised
    KIAB likes this.
  7. Malcolm Douglas

    Malcolm Douglas New Member

    Thanks guys,
    If I was to cut the pipe would I not be able to leave the 'insert' part of pipe (that which goes into the collar) intact and just remove the collar and part of the pipe? Sorry for poor terminology! The pipe that come out of the bottom of the concrete block at a 90 degree angle seems too short to cut away?

    Attached Files:

  8. KIAB

    KIAB Super Member

    It is very difficult working from a photo & not seeing the actual pipe.

    But, looking at your second photo,the penny dropped:oops:,was too early,need coffee to function.:)

    You are right, forgot to allow for the pipe insert into bell end, cut on furthest white line should give you enough room for repair.

    Possible might have to cut even further back & use a shallow bend (you can get adjustable bends) to allow you to get perfect alignment, all depend on pipe & it's angle coming from concrete block.
    Last edited: Jul 5, 2018
  9. Isitreally

    Isitreally Super Member

    Seal with silicone, cover with concrete, forget about it and get on with patio.
    rogerk101, WillyEckerslike and PhilSo like this.
  10. seneca

    seneca Screwfix Select

    That would be my answer, Isitreally, dig around the cracked area, seal with silicone and then use it for a few days to make sure there's no leaks and then concrete the whole area in.
  11. KIAB

    KIAB Super Member

    Temporary bodge.:)

    Old school way may taken longer, but you know it unlikely leak.
  12. seneca

    seneca Screwfix Select

    It'll hardly be temporary if it's encased in concrete!
  13. Dr Bodgit

    Dr Bodgit Super Member

    Stixall FTW! :D
    KIAB likes this.
  14. KIAB

    KIAB Super Member


    Someone had to mention it.:D
  15. rogerk101

    rogerk101 Screwfix Select

    Clear out the whole area of mud/dirt ... spray the whole lot down with a hose, getting the internals of the crack as clean as possible ... let it dry ... smear some sticks-like-**** or something similar into the crack ... worry about it in the extremely unlikely event that it ever poses a problem.
    It's not a problem now, so is even less likely to be a problem in the future.
    The only risk it presents now is that roots might find their way into the pipe, but if you seal it off well using above method, that's extremely unlikely to happen.
    seneca likes this.
  16. seneca

    seneca Screwfix Select

    I can see you live and work in the "real world" Rogerk!
  17. Hi

    Hi I’m a newbie

    I’m so glad I came across this post. I did a similar thing. I’m currently digging a pond. However I’ve just hit a 6 inch hole into a clay rain/ storm pipe. Would I need to use flexiseals and pvc pipe or can I cover the hole with hard bendy plastic & pond mastic ?
    I’m concerned about cracking it more if I try to dig round it.
    Thanks for any advice in advance.
  18. pppmacca43

    pppmacca43 Super Member

    Try upload a photo if u can
    MotherTruckerPucka48 likes this.
  19. Hi

    yeah sorry that would help lol

    Attached Files:

    Crowsfoot likes this.
  20. pppmacca43

    pppmacca43 Super Member

    Ideally I would say needs to be cut out and replaced unfortunately. A patch would work as a temporary measure but is a bit of a bodge as a permanent job

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