Noisy Soil pipe

27 Nov 2021
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United Kingdom
Hi all,
I have recently had major works done in my flat, with walls and partitions being removed and redone because of previous damage.

following this the soil stack has gone way louder than it was before, it makes a bad knocking sound as if something is banging from behind the wall whenever someone on the flats upstairs flushes their toilet.
its usually worse when it hasn't had anything go through it for while.

the boxing that encloses the pipe doesn't seem to have any kind of insulation as far as I can see so I figure that is one issue,
but other than that I wonder if there might be any other potential cause we should be aware of or look into?
thanks for any advice.

edit: I'm attaching an audio file of what it sounds like.


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It may be the sound travelling through the boxing and the new stud walls, rather than the soil pipe itself - insulation might dampen the noise.

thanks @blup! but what would be the cause of the sound, the pipe hitting the boxing as it vibrates?

should the insulation go both around the pipe and the walls of the boxing?
Difficult to say, if the pipework is loose that would be a concern; it might be the boxing, or loose woodwork somewhere. It sounds like you have a long leasehold so your neighbour ought to co-operate.

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There are various additional parts in a concealed cistern, if fitted, which could be creating the noise.


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