Internal coupling for vertical PVC sewage pipe?

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wwhitney

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- The studs are 3.5" deep (2x4s).
- The shielded coupling is about 1/2" thick. The pipe and coupling together is about 4 to 4 1/8" diameter.
- The 3" PVC coupling is about 1/4" thick and per Google, should be about 3.5" in diameter.
No, the diameter of the 3" nominal pipe is 3.5", and so the PVC coupling should have an OD of about 4". Hence the difficulty of putting it in a 2x4 wall.

Since the shielded coupling is the largest diameter, if you have access and clearance below, it might be possible to move all the shielded coupling(s) down below. That coupling is also the wrong type (it's for use underground), although that version is arguably as beefy as the correct type. The correct above ground type (Fernco Proflex 3005-33 or Mission Rubber Band Seal P-300) might have a smaller diameter, not sure.

You'll still be left with the difficulty of the 4" OD on the PVC coupling, however.

Cheers, Wayne
 

Haneyeam

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No, the diameter of the 3" nominal pipe is 3.5", and so the PVC coupling should have an OD of about 4". Hence the difficulty of putting it in a 2x4 wall.

Since the shielded coupling is the largest diameter, if you have access and clearance below, it might be possible to move all the shielded coupling(s) down below. That coupling is also the wrong type (it's for use underground), although that version is arguably as beefy as the correct type. The correct above ground type (Fernco Proflex 3005-33 or Mission Rubber Band Seal P-300) might have a smaller diameter, not sure.

You'll still be left with the difficulty of the 4" OD on the PVC coupling, however.

Cheers, Wayne
Thanks Wayne! I am messing up all over the place. :confused:

So the PVC coupling is 4" exterior diameter as you said.

My drywall is 3/4" thick, so removing the shielded coupling and running a new pipe from the existing PVC coupling down into the crawlspace should leave just 1/2" to carve out of the back of the drywall at the location of the PVC coupling. That would be a heck of a lot better than what I have now!
 

Reach4

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A modern 2x4 is supposed to be 3.5 inches with some tolerance.
 

Haneyeam

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A modern 2x4 is supposed to be 3.5 inches with some tolerance.
Yep! So with the PVC coupling with 4" external diameter, I'll need to carve out about a half an inch from the backside of the drywall. That's after removing the shielded coupling.
 

Jeff H Young

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its a tight fit but if the pipe was in the wall befor it should still fit the coupling should only take a 1/4 inch on a side so like mentioned scarf out drywall so it doesent bow the wallboard
 

Haneyeam

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Less if you also carve out the exterior sheathing assuming there is sheathing. What kind of siding is on the exterior?
It is vinyl siding. The back of the cavity is OSB.

its a tight fit but if the pipe was in the wall befor it should still fit the coupling should only take a 1/4 inch on a side so like mentioned scarf out drywall so it doesent bow the wallboard
Yep, that's the plan!

Everyone has been very helpful, thank you!
 
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