Noisy plumbing vent

Local Inspection Issues Canadian Home Inspectors
#1

This came to me any thoughts appreciated … Roy
…
Carol
Great question .I have thought about this but before I make my answer known,
I will Put this to a few friends In Industry to get some feed back .
I should be getting back you in a few days .
Thanks … Roy

----- Original Message -----
From:
To: info@royshomeinspection.com
Sent: Saturday, April 23, 2011 7:22 PM
Subject: Re: Your advise would be appreciated

Hello Mr. Cooke:

** My husband and I have heard you give advise on the Lorne Brooker show and we were wondering if you could give us a little advise.**
** We have an air stack on the roof that vibrates every time the wind blows hard. The stack runs from our bathroom in the basement level up through to the bathroom in the upper bathroom then up through the roof. We have a side split house. The pipes run between a wall that separates the toilet area from the shower area in the upper bathroom and that is where we hear the vibrating. We really do not want to open any walls unless we can find out what is making the pipe rattle. We have had the stack on the roof checked and it is tight up there. Any advise you can give us would be very much appreciated. Thank you. … Carol**
Carol

#2

They would not have that issue with cast iron.Sounds…get it…sounds…funny right.:slight_smile: like they need insulation in the wall.

#3

Not just regular batt fiberglass but a low expansion foam in the area of the pipe. Can be installed with a series of 1/4" holes.

Higher density blown cellulose would also probably work…can be blown through 3/4 or 1" holes which patch easilyalso.

#4

Hi Roy:
The vent stack can not be one piece from bottom to the top. So basicaly to extend the vent stack we need coupling. An improper connection ( pipe to coupling) leaves a gap. This gap works like human lips, tongue and teeth. Whenever we want to whistle, we just need to keep our lips, tongue and teeth in specific shap and then push the air from our mouth through the gap. In your case, you already have the gap we just need to push the air through the gap so in windy weather we have all the requirements.
I hope it helps.
Cheers
Maz

#5

Roy, here is my take on the problem.

What is the size of the vent stack? How much is extended above the roof?
Try to extend it or shorten it to change the dynamics of air flow and turbulence over the top of the pipe.

Stacks can vibrate in the wind. Could be tricky to solve. You might try cutting the pipe at a slight angle at the top, with the high point in the direction of the prevailing wind.
They make a vent cap that has the air come in or out below the top, that keeps the wind from creating a suction at the top of the vent. Plumbing supply houses should have them, give them the size of vent and the material its made of.

Pipe could be loose up in the attic and in the wall by over-cutting the wall plates and was not secured properly.
Try securing in in the attic where it comes out of the wall.

If you have access in the basement, have someone stand down there with their hands tightly grasping the offending drain line/stack. The idea is to see if you can muffle the sound by dampening the vibration.

#6

Try a elbow

#7

If the wall exit point was accessible in the attic and the hole in the top plate was oversized (as it always is), foaming there may stop the vibration but would also be a step in airsealing the home and stopping heated air loss with moisture into the attic.

#8

I think what you have is a pipe organ effect. Much like blowing over the end of a bottle. Cutting the edge of the pipe as suggested above, adding 45 elbow, or even drilling some holes an inch or so below the lip of the pipe ( to change the resonant length) might do the trick to stop the noise.

If it is the pipe actually vibrating then it should be a simple matter of securing the pipe somewhere between the roof line and the ceiling joists to once again change the resonant length of the pipe.

#9

Thanks to all for your ideas . I too like Brian had thought of the spray foam .
I think the angle cut on the pipe might work in most winds BUT might also be worse in some direction cupping in more wind, same thing with a 45° cuping more wind and possible raising the presure in the vent . My answer .
…

I think what you have is a pipe organ effect. Much like blowing over the end of a bottle. , or even drilling some holes an inch or so below the lip of the pipe ( to change the resonant length) might do the trick to stop the noise.
Adding some length to the pipe might be the easiest to do if you have some one who can work on the roof .
If the pipe is does not extend above the roof about 14 inches adding a coupling and a piece of pipe might be adequate ,I do not think you need to glue it to see if this will work.
If This does not help then I would get spray foam at your hard ware .
I would measure where the pipe is and punch a 1/4 hole ( Do not drill in case you drill into the pipe or cut an electric wire )( a screw driver should work well ) beside the pipe .
The spray foam should lock the pipe in the wall and stop the vibration .( more then one place recommended)
Send me your phone number or call my cell 613-827-2011 if you want me to explain
All the best Thanks for your question .

Please do not give up will win . Roy Cooke .

#10

Reply
…
----- Original Message -----
**From:**Xxxxx Xxxxx
To: Roy Cooke
Sent: Monday, April 25, 2011 7:47 PM
Subject: Re: Your advise would be appreciated

Thank you so much for the info. We will try one of them and hope it works, **
** if it doesn’t I will give you a call. Thanks again. … Xxxxx****

I wish you good fortune ,Please let me know how it works Out … Roy