Help identifying hollow banging noise under house

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timmmay

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# 205572 18-Nov-2016 08:12

From my bathroom I can hear this weird noise (soundcloud link, few seconds of audio) from my bathroom sometimes when the wind blows. It can happen every 5 seconds then not happen for 5 minutes, or it can happen every ten seconds for minutes. It's not regular. My wife doesn't notice it. Anyone care to guess what it is?

Here's what I know:

I hear the noise intermittently from my bathroom when the wind blows - there's no regularity to it
I can feel a short, sharp vibration (ie a bang) through my feet when I hear the noise
You can't hear the noise when you're sitting outside the bathroom in the wind
It's been happening for months but seems to be getting a bit louder
I've been under the bathroom and I can't see anything loose. I put a bit of padding between two pipes that were close together
It could be something hitting something else, or something becoming unbalanced
It's a hollow sounding "bong / bung" type nose
House is 100 years old (ish), with a new bathroom
(Update) I haven't observed any correlation with water use, either in the bathroom or the rest of the house

Any ideas what it could be?

I know most people will say "go have a look". Unfortunately I have a sports injury that means crawling around under the house isn't possible. I'm not even sure who I'd get to look at this - a builder, plumber, or handyman?

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# 1673336 18-Nov-2016 08:23

Is it related to using water? I get some weird sounds when I turn the tap off in bathroom

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timmmay

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# 1673340 18-Nov-2016 08:30

I haven't observed any correlation with water use, either in the bathroom or the rest of the house. I can only hear it when it's quiet in the bathroom, with no taps running.

MikeB4

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# 1673352 18-Nov-2016 09:06

Do you keep an outside hose tap turned on with a hose attached?

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Coil

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# 1673356 18-Nov-2016 09:13

You may find it will be pipes moving from something drawing water, Most likely your hot water cylinder.
The momentum in the water is quite strong when it stops flowing instantly, With old plumbing it can jolt the pipe work down the line. Some instances you can get a tap vibrate or resonate really badly with hot water, Super loud farting like noise.

Edit: Added below.

IIRC you have a recent build right? Brick and tile? If so most of your plumbing will be in walls and probably is plastic so might not be plumbing. (If the above is true)

Do you have a central vac?

frankv

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# 1673366 18-Nov-2016 09:26

It could be that the noise is generated elsewhere, and conducted along the pipes to where you hear it in the bathroom.

Bung

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# 1673368 18-Nov-2016 09:27

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Correlation is "when wind blows". Do you have a toilet in bathroom? Sometimes the wind blowing across vent pipe can cause the water in the trap to bounce around and sometimes empty. If you've noticed anything like that happening maybe that's where the noise is coming from.

timmmay

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# 1673397 18-Nov-2016 10:00

MikeB4:

Do you keep an outside hose tap turned on with a hose attached?

Not anywhere near there, and no not always.

TimA:

You may find it will be pipes moving from something drawing water, Most likely your hot water cylinder.
The momentum in the water is quite strong when it stops flowing instantly, With old plumbing it can jolt the pipe work down the line. Some instances you can get a tap vibrate or resonate really badly with hot water, Super loud farting like noise.

Edit: Added below.

IIRC you have a recent build right? Brick and tile? If so most of your plumbing will be in walls and probably is plastic so might not be plumbing. (If the above is true)

Do you have a central vac?

Nothing is drawing water when this happens. For example this morning I was the only one up and hadn't used water for 5 minutes, no washing machine or dish washer was on. When taps are running strongly and get turned off I do hear a clunk, but it's quite different to this.

The house is very old, the bathroom is tile with plastic and copper pipes. Plumbing is ceiling, wall, and under floor.

frankv:

It could be that the noise is generated elsewhere, and conducted along the pipes to where you hear it in the bathroom.

Interesting idea, thanks.

Bung: Correlation is "when wind blows". Do you have a toilet in bathroom? Sometimes the wind blowing across vent pipe can cause the water in the trap to bounce around and sometimes empty. If you've noticed anything like that happening maybe that's where the noise is coming from.

Yes there's a toilet in the bathroom. The sound doesn't come from the toilet trap, it comes from under the floor somewhere, but that's something worth considering, wind into a pipe like that.

Adamww

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# 1673415 18-Nov-2016 10:25

Do you have a ducted extractor fan in there? Some of those have one-way non-return flaps in them that can be pulled open by wind and bang closed.

timmmay

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# 1673426 18-Nov-2016 10:39

Adamww:

Do you have a ducted extractor fan in there? Some of those have one-way non-return flaps in them that can be pulled open by wind and bang closed.

Yes ducted extractor fan, no flap. Good thinking but the noise is definitely coming from the floor not the ceiling.

webwat

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# 1673482 18-Nov-2016 11:16

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It sounds like a piece of timber is kind of teetering on a loose nail or something, just enough to upset its balance when a bit of wind gets on it. I would say its a job to put on the backburner until after you're back to 100% over the sports injury, but any handyman should be able to crawl under and have a closer look. Give a kid $10 to crawl around. EDIT: and some knee pads and safety glasses!

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