PVC pipe in attic- not sure what it is

House was built in 2004, hip roof. When we moved in, 2010, the house had no attic entry. I made one and found that there was a 2" PVC pipe that runs to the soffit. I had to move it, while moving it, a little bit of water came out. It points down to the soffit. I'm not sure what it's purpose is as we have a stink pipe that goes up through the roof where all fixtures, etc run to a main run to that vent.

I traced it back to the main pipe that everything looks to connect to and it is branched off with a y fitting.

We have no AC, HVAC, etc in the attic.

What could this be and can/should I remove it/cap it?

Is thatthe pipe that penatrates the roof??????you canput a rubber cap on it but until you know what it is dont cap it permanently
Can you show pics???????

Hi,

I don't have a photo, but this is not the pipe that penetrates the roof. We have a main pipe that all other fixtures plumb into, that main pipe (it's big, maybe 4 or 5") runs the length of the attic, and then goes up through the roof.

The PVC pipe that I'm asking about is a branch from the main run that runs over to a soffit and has a 90 elbow that just points down to the soffit, not even through it.

Fhjaarpd .troq ®<

Geofd said:

Is thatthe pipe that penatrates the roof??????you canput a rubber cap on it but until you know what it is dont cap it permanently
Can you show pics???????

Click to expand...

Hard to say what it is unless you can see te same pipe(if if you can) in the basement (tap on it) i dont know what it would be

Don’t cap it.

And why, how did you move it?

It might be a plumbing vent installed by someone too lazy to punch a proper hole in the roof.

If you cap it, that would cause trouble.

Call a plumber to investigate, you need pro help on this.

Call an expert plumber before its going to late.

I think that I may have mis-describbed this. I'll start over.

When we moved into the house, 4 years after it was built, there were no entrances to the attic. I made a hole to get into it. This pipe, was right over that hole so I cut it back, put 2 90's on it to re-route it, during that process, a little but of water came out (condensation?). That pipe is still in the way and I want to either cut it back and cap it or just re-route it again but I'd like to know what it is. This pipe y's off of the main horizontal pipe that leads up through the roof. Our bathroom, sinks, etc connect to this main pipe from what I can tell. I say it's a main pipe because it's much larger than the other pipes that connect to it.

All this explaining....

Post pictures of what your talking about please.

I can rxain to you that I saw this long black hard object that was full of seaman.... but would you have guessed it was a submarine???

Mainer81 said:

I think that I may have mis-describbed this. I'll start over.

When we moved into the house, 4 years after it was built, there were no entrances to the attic. I made a hole to get into it. This pipe, was right over that hole so I cut it back, put 2 90's on it to re-route it, during that process, a little but of water came out (condensation?). That pipe is still in the way and I want to either cut it back and cap it or just re-route it again but I'd like to know what it is. This pipe y's off of the main horizontal pipe that leads up through the roof. Our bathroom, sinks, etc connect to this main pipe from what I can tell. I say it's a main pipe because it's much larger than the other pipes that connect to it.

Click to expand...

So are you saying that the 2" PVC pipe in question y's off a larger main horizontal pipe that leads up through the roof and the other end runs to the soffit. And that there are no other branches on this 2" line?

So the obvious appears to be that this line has no useful function and you are hoping that someone might offer a guess as to it's intended function?

I must ask as some of the comments seem to be assuming otherwise.

What color is this pipe?

Diehard said:

So are you saying that the 2" PVC pipe in question y's off a larger main horizontal pipe that leads up through the roof and the other end runs to the soffit. And that there are no other branches on this 2" line?

So the obvious appears to be that this line has no useful function and you are hoping that someone might offer a guess as to it's intended function?

I must ask as some of the comments seem to be assuming otherwise.

Click to expand...

Correct, this pipe in question that leads to the soffit has no other branches from it. I can get photos when I go up into the attic this Friday. I'd like to know if anyone has seen this, that this is normal, not normal etc as I'm not a plumber.

It's a white schedule 40 PVC pipe.

From the responses received so far, it would appear that it is neither normal nor can anyone speculate as to why someone would do that.

Possibly the furnace vent. Those vent horizontally under a soffit sometimes

Rickyman said:

Possibly the furnace vent. Those vent horizontally under a soffit sometimes

Click to expand...

Furnace vent???
It only goes from main vent which goes through roof to the soffit. No other branches!

Mainer81, you do not know what the heck you are doing.

Stop screwing with that pipe, stop guessing, stop trying to have others guess for you, remotely.

You should never have touched it, cut it, or changed anything if you have no idea what you are doing.

You might already have created a dangerous or stupid situation, adding elbows to a pipe that you have no frigging idea why it’s up there.

Call a pro, or cheap out and hope it magically fixes itself.

It only goes from main vent which goes through roof to the soffit. No other branches!


EDIT: Correction. OP now points out that there is a branch from a washing machine!

Jeff, I'll post some photos later in the week- I'm not looking for concrete answers- just some ideas. I'm pretty certain that it's nothing serious, putting elbows in to re-route a pipe shouldn't cause any problems if glued correctly. I did this several years ago and now am more curious as to what it is. I do plan to call my plumber. Thank you though for the concerns, I do appreciate it.

The furnace (boiler) is a direct vent. Our radon mitigation system vents outside and runs up the exterior wall.

Good morning. I found some older photographs, before I added more insulation.

I've noted the photos with text. I forgot that our washer has pipe running to this pipe in question. Could I possibly cap after the washer pipe so that this is not venting out and down into the soffit?

The only thing that comes to my mind is the need to slope the vent lines back to the drain.
Is there a chance that the person that installed that leg out to the soffit, did so because it wasn't pitched back to a drain?

Do not cap it.

If it is not causing trouble now, why would you cap it, that sounds nutty to me.

Maybe the washer drain was gurgling or backing up, so they added that extra vent/intake at the soffit?

As Diehard said, if any vent section was not draining, it could gradually fill with water and stop letting air in or out as needed.

Water can fill up the pipe from rain entering the roof vent, or from condensation inside the cold pipe eventually filling it up, due to a belly or poor slope.
This situation is not uncommon in long horizontal vents in attics.