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Banging noise in walls when I flush a specific toilet.

  • Last Updated:
  • Nov 27th, 2019 9:46 pm
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Feb 4, 2015
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Canada, Eh!!
themank wrote:
Nov 18th, 2019 7:13 pm
Negative, it's ONLY when the toilet is flushed which is why this has me stumped. I can hear the water flow when doing as you suggested but there is no banging.
Flushed with anything? Whether it be pee or poop with toilet paper? Just wondering if more volume causing noise or does not matter.
[OP]
Member
Nov 20, 2015
340 posts
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Calgary, AB
georvu wrote:
Nov 18th, 2019 7:47 pm
Flushed with anything? Whether it be pee or poop with toilet paper? Just wondering if more volume causing noise or does not matter.
Yup, even flushed with nothing in the bowl.
Member
Mar 15, 2007
475 posts
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Toronto
After we had our third floor bathroom renovated we started getting a knocking noise in the walls when we flushed the toilet (Toto dual flush) in the second floor bathroom.

I took apart the fill valve and there was something that looked like a small rock or piece of concrete lodged in the filter. After cleaning everything up in the fill valve there was no more knocking after flushing.
Sr. Member
Oct 3, 2011
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OTTAWA
drain pipe is just banging on the drywall or framing.. probably just strapping that came loose over time. But since I have a similar bang, I'm subscribing to this thread lol.

I'm pretty sure I know the fix required... I just don't want to cut open my wall again.
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nonlinear wrote:
Nov 19th, 2019 8:11 am
After we had our third floor bathroom renovated we started getting a knocking noise in the walls when we flushed the toilet (Toto dual flush) in the second floor bathroom.

I took apart the fill valve and there was something that looked like a small rock or piece of concrete lodged in the filter. After cleaning everything up in the fill valve there was no more knocking after flushing.
This is very common to get sediment in fill valve also in tubing. Also with some flappers there are holes over time that fill up and hamper the seal.

I believe in this case it is as lurkknight says.
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lurkknight wrote:
Nov 19th, 2019 12:27 pm
drain pipe is just banging on the drywall or framing.. probably just strapping that came loose over time. But since I have a similar bang, I'm subscribing to this thread lol.

I'm pretty sure I know the fix required... I just don't want to cut open my wall again.
Yeah would be good to be able to pinpoint where to rip drywall... stethoscope? Have similar noise in one of our bathroom.

Op: Might also want to check in basement where can see drain pipe if can feel/see any movements when someone else flushes toilet.

Unlikely but also check by adjusting stop valve... close for less pressure.

Another far off idea... try flushing toilet and have someone hold/further close faucets in bathroom especially if have separate shower... if feel vibration there or further closing helps then could be a cartridge... Again highly unlikely but might as well try before ripping up any drywall. We had noise once toilet stops flush and whenever close sink faucets in one of our bathrooms... by chance happened to put hand on shower handle and felt vibration. Changed shower cartridge [delta $30USD!!] and no more noise.
[OP]
Member
Nov 20, 2015
340 posts
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Calgary, AB
Right! So the plumber described it as "water slap". The banging noise wasn't nearly as loud when he was there - it seems to be loudest first thing in the morning and after a few flushes it is not as loud. He basically said there is nothing you can really do without opening up some walls and even then there is probably not much you can do. With some of the pipes in the utility room you can see that they are really close to the framing or even have some framing chisled out to hug the pipe. He doesn't think that it is a strapping issue. So I guess we live with it until we decide to paint the house then we can open up a wall and check it out.

I really think we are probably overreacting because this is the first time we have lived in a 2 storey and haven't had to hear water running through pipes in the main floor walls.

I'm glad we had it checked out, just to put our minds at ease!
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Oct 15, 2007
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themank wrote:
Nov 27th, 2019 1:58 pm
Right! So the plumber described it as "water slap". The banging noise wasn't nearly as loud when he was there - it seems to be loudest first thing in the morning and after a few flushes it is not as loud. He basically said there is nothing you can really do without opening up some walls and even then there is probably not much you can do. With some of the pipes in the utility room you can see that they are really close to the framing or even have some framing chisled out to hug the pipe. He doesn't think that it is a strapping issue. So I guess we live with it until we decide to paint the house then we can open up a wall and check it out.

I really think we are probably overreacting because this is the first time we have lived in a 2 storey and haven't had to hear water running through pipes in the main floor walls.

I'm glad we had it checked out, just to put our minds at ease!
Water hammer is most often due to a failure in the system and not solely because of pipes that aren’t supported. It is also difficult to diagnose especially over the Internet. The most common culprits are a failed toilet fill valve, a shutoff valve with a loose washer or valve not completely open. There are other possibilities but these are the first things I would look at
Everything has been said before, but since nobody listens we have to keep going back and beginning all over again. - Andre Gide

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