Leaky stack

Discussion in 'Plumbers' Talk' started by Mark Griffiths, Jul 22, 2020.

  1. Hey all,

    I’ve recently pulled out my kitchen to fit a new one and I’ve just noticed a wet patch at the bottom of the soil stack from the bathroom.

    On closer inspection the clamp has broken on the fitting and there is a small trickle coming out when water is draining from the bathroom.

    What is the repair method for this?

    Dig out the stack/replace the fitting/a tube of sealer?

    Thanks in advance.

    Attached Files:

  2. terrymac

    terrymac Screwfix Select

    Remove the strap on boss. Which should be solvent welded to the soil pipe and may not be easy to remove.
    Clean up the mating surface and fit a new boss.
  3. Thanks, it’s good to know it’s not a dig out the floor scenario.
  4. terrymac

    terrymac Screwfix Select

    As long as you can remove the boss without damaging the mating surface of the soil pipe ,and have the space to fit a new boss it's doable.
    Unfortunately you will not know until you start to remove it.
  5. And if I can’t?

    what’s best to remove old solvent residue?

    sand paper?
  6. terrymac

    terrymac Screwfix Select

    If you can't remove the boss ,without damaging the pipes mating surface ,then it would have to be replaced ( in part) ,probably. Unless the white waste pipe can be re routed ,to a higher level.
    Can it ? What does it connect to and where ?
    Any residue can be sanded off.
  7. Tricky Dicky

    Tricky Dicky Active Member

    Hi, is the brown soil pipe also cracked, just below the grey strap on boss connector ?
  8. sparky steve

    sparky steve Screwfix Select

  9. Hi all, sorry for not responding to the previous posts, I didn’t see them until now.

    the brown pipe is not cracked and I managed to get the boss off without damage.

    unfortunately I can’t get a good seal at that connector for some reason. It seems like the solvent weld just isn’t doing the job. The tub is in date and been stored correctly so I don’t think it’s that.

    I’m now wondering if there is a blank that I could put over the hole and use a different fitting which is now unused slightly higher up the stack (see photo).

    does anyone know if there’s a blank for the hole in the stack?

    Attached Files:

  10. NoOhmToGoTo

    NoOhmToGoTo Screwfix Select

    Don't use solvent weld, use silicone.
  11. nigel willson

    nigel willson Screwfix Select

    You need gap filling adhesive not the normal one
  12. Ah, that’s interesting. I can’t see anything on the Screwfix site matching that description.

    Aany chance you would be able to share a link or name that I could search?
  13. Im tempted by this, but silicone seems like a temporary solution to me, this will be boxed in and access would not be easy in the future. It needs to be a permanent fix. Can silicone be relied on?
  14. terrymac

    terrymac Screwfix Select

    Have you cleaned the pipe ?
    Is it a new strap on boss ?
    Did you apply solvent cement to both pipe and boss ?
  15. terrymac

    terrymac Screwfix Select

    Floplast is one of the thicker solvent cements.
    The hole in the pipe looks quite a large diameter ,but maybe the pic is deceving. How much surface area is actually in contact ?
  16. Yes, yes and yes...
  17. It’s a 54mm hole, there is probably only 1mm play in the fit. It started as a 50mm, I had to enlarge It to get the new boss to fit. Loads of contact area.

    Floplast solvent is the one that I used. I’ve not had a problem with it before, it’s so strange.
  18. The only thing that I can think of that I did differently to normal is because it is not a new stack, I cleaned it off with sand paper to a good surface. Then to make sure that there was no adhesive or dust I gave it a wipe off with white spirit.

    gave it a couple of minutes to dry off before applying the solvent. But maybe that had an effect?

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