How to clear a plumbing vent from below
December 5, 2022 3:29 PM   Subscribe

My home is exhibiting signs of a plugged vent. I really don't want to go up onto our steep roof in the winter to mess with it. Can I do this from below?

The only place I have easy access to what I believe is the pipe in question is in the basement of a two-story house. I can picture drilling a hole into the ABS there and fishing a snake upwards. In my picture, the snake is rigid enough to make the trip (I would rent a big one).

Roof access is a no-go. My 30ft ladder juuuust barely touches the eaves there, and anyway the roof is too steep.

Attic access was just attempted, but there is about 6ft at the edges of the house where the attic floor ends but the roof keeps sloping below (like a capital A with the inside of the hole being the attic).

I fully expect to find that I just need to call someone to climb up there and clear it, but first I thought to ask if anyone has seen or heard of this being done from below.
posted by Acari to Home & Garden (9 answers total)
What's your plan to patch the hole you drill in the vent? I'd be really worried about sewer gas ending up in my house. Personally, I'd hire someone to do it.
posted by AaRdVarK at 4:26 PM on December 5, 2022

There's probably a screen on the pipe up there, so you can’t count on pushing the plug out if there is one.

But in any case (see the diagram with this article), I don’t see why you wouldn’t put the snake up the regular sewer cleanout in the basement rather than down as you would to declog the sewer. It might be a bit tricky to make it go up in the first place, but I bet you could do it.

I think that could work, and if there is a plug you could pull it down and out of the cleanout instead of trusting that it wouldn't clog your sewer lower down.
posted by jamjam at 5:20 PM on December 5, 2022 [1 favorite]

Best answer: What are the symptoms? I ask because I also thought I had a clogged vent, due to several symptoms...

1. slow flushing toilet
2. bad smells from sink near the toilet
3. sewage smells in downstairs bathroom

Later has a roof job done, and the roofers confirmed the vents were fine.

The causes turned out to be unrelated:
1. toilet was just old and poorly designed
2. sink smells were due to gunk building up in the p-trap - using more hot water & occasional bleach fixed it
3. the city notified us that the sewage pipeline near our house had a tendency to clog, so they send out a truck to blast it clean every once in a while.
posted by soylent00FF00 at 7:26 AM on December 6, 2022 [1 favorite]

Response by poster: Thanks for your answers so far.

I do have a plan (2 plans - one for now and one for the spring) for patching the pipe. It's ABS, so I know for sure I can make a great repair and then later a repair that's not actually stronger but will be up to code.

Access from the sewer cleanout is not something I considered. I have sincere doubts as to whether I can get around the corner, but I'll definitely try it before damaging any pipes!

Symptoms are as you listed, soylent00FF00, with the addition of bubbling from all lower drains when a higher-up drain is used.
Your cause #3 is a real contender, too. This house is about 110 years old, so any and all issues are possible!
posted by Acari at 9:35 AM on December 6, 2022

Response by poster: Well,
With my skills, it is not possible to get the snake to turn the wrong way and not go down.
I also tried out sending a snake up a 4" pipe (using the 4" pipe I have handy for making cat trees), and... I'm not going to try drilling a hole and going up from the basement. I've got no control.

I've called a bunch of plumbers but nobody wants to climb onto my roof in the winter. I can't blame them!
I'm going to either just wait for a warmer day and rent a ladder, or else maybe call a roofing company.
posted by Acari at 11:13 AM on December 7, 2022

I see ads about drone inspections by roofing contractors, and I wonder whether a few bucks dangled in front of local drone hobbyists might not get an enthusiastic response if you could find such people.
posted by jamjam at 1:57 PM on December 7, 2022

Response by poster: I cut a hole in the wall near the roof and snaked the vent pipe from there. No luck!
Upwards only found soft, clean snow
and downwards went to the end of the snake with no obstructions.

I'm marking the 'it might not be the vent' answer as best because it might not be the vent!

Turns out that zero years of plumbing school didn't prepare me as well as I'd hoped for an oddball problem.

On the bright side, if it's not a problem with the gassy exit, it's got to be a problem with the gross sludge exit. That's something plumbers will come out for even in the winter.

((also - I tried to rent a 40ft extension ladder but they wouldn't let me take it home on my roof racks despite my assurances that I do dumber stuff all the time.))
posted by Acari at 5:52 PM on December 7, 2022 [1 favorite]

Response by poster: It was roots 70 feet (2 feet shy of the property line!) down the sewer. I got to operate the giant sewer auger on a cart thing, which was fun! Now I'm back to living like a king whose poop magically disappears without reappearing in the basement.
posted by Acari at 12:18 PM on December 9, 2022 [1 favorite]

“Upwards only found soft, clean snow”

I mean, that counts as a blockage. Did your problems start with the onset of winter weather, by chance?
posted by misterbrandt at 10:17 AM on December 18, 2022

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