# Sewer smell from under sink and adjoining closet, but not from drains?



## Mike Swearingen (Mar 15, 2005)

Sounds like you may have a leak in a drain pipe. Is this downstairs bathroom over a crawlspace or basement where you could look around see evidence of a leak?
Mike


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## aaronb9 (Sep 2, 2009)

Unfortunately it's not. As far as I know, the house sits on a one piece concrete slab. This room is against an exterior wall. If it's relevant, the house is wood framed, stucco exterior and is essentially single-storey but with a bonus room and bathroom upstairs.


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## james schroder (Sep 1, 2009)

*bathroom smell*

If there is a floor drain in the bathroom the trap could be dry, also if there is a toilet the seal could be leaking gas but not water unless there is back presure. Resetting it could solve the problem.
James


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## aaronb9 (Sep 2, 2009)

Thanks for the info, there's a floor drain in the shower, but it gets regular use (2x a day) so I don't think the trap is dry.

We recently had a blocked toiled drain that wasn't solveable by plunging or chemicals, and called a plumber out. There isn't a close by cleanout so he removed the toilet to snake through there. He did fit a new wax gasket to it, and surprisingly the smell is barely noticable in the water closet, which adjoins the sink cabinet.

Some more information:

It rained heavily today, and the odor has got worse. It's now noticeable throughout the whole house. I also noticed the ground seemed more damp outside the affected area.

I removed a plastic trim/sealing ring from where the sink drain exits the back of the cabinet, and the odor seems to be coming from there.

There is a roof vent right above this area, but it appears to be clear. I was able to lower a length of hosepipe into it, and when the toilet is flushed/faucet is run I hear water clearly through it.

Based on the above, is it fairly safe to assume it's a cracked or leaking pipe somewhere in the wall or below the floor? If so, any ideas what should I expect as far as getting it repaired?


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## LanterDan (Jul 3, 2006)

Just to make sure we haven't missed anything simple: Are you sure there isn't a failed AAV/mechanical/cheater vent under the sink? 

I recently experienced this problem. Before I figured it out it, the smell was worse some days compared to others for reasons I never figured out.


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## flat4 (Aug 30, 2009)

I vote for the leak under the house, when small amount of water can collect in the dark ( as was in my house ) it starts to get funky down there in the summertime


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## aaronb9 (Sep 2, 2009)

LanterDan said:


> Just to make sure we haven't missed anything simple: Are you sure there isn't a failed AAV/mechanical/cheater vent under the sink?
> 
> I recently experienced this problem. Before I figured it out it, the smell was worse some days compared to others for reasons I never figured out.


There is one of these in that bathroom but it's under the other sink (two sinks, one on each side of the room). The one with the mechanical vent doesn't smell at all, although I noticed today it drains a bit slower than the one with a 'real' vent. Any way to test these cheater vents? I know if they stick open they will smell horrible, but I'm wondering if this one could be stuck closed or not opening properly.

Had some different plumbers out today, they ran the smoke test and thought that a join in the vent pipe right before where it exits the roof was to blame. I'm not totally convinced yet (the joins looked pretty good after it was removed) but it's hard to tell, it's been dry and the smell has almost gone on it's own.

I did run that sprinkler zone for an hour today to try and get the smell to come back, but it didn't. So perhaps it's not linked to wet ground afterall.

I'm desparately hoping this will have solved it and that no slab work is required, but I guess I won't know until it next rains heavily.

Thanks for all the advice, it's much appreciated.


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## kennygm (Sep 5, 2009)

*sewer smell*

We currently have the same problem and as we recently had a plumber here twice fixing leaks and replacing toilets, I knew it wasn't in the house. 
I decided it was time to call the City's Public Works Dept. (we're still waiting for them to arrive). 
One of my neighbours just had a sewer back-up problem and had to move out for a week while floors were ripped out and pipes, flooring etc. were replaced. 
We have this added coverage on our insurance and hope you do too. I'll let you know how it turns out.


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## aaronb9 (Sep 2, 2009)

Sorry to hear that, this certainly is no fun, that's for sure. I might try asking the neighbors if they have any similar issues.

I've pulled out some more fiberglass insulation from the wall behind the sink today, and here's what I saw: (dimensions are approximate)

The 2" vent pipe enters an open 4" pipe just above floor level. It's pressed against one side, and has pieces of wood wedging it in place on the other side.

There's not very much gap between the inner pipe and the outer pipe, but there is some. 

I dropped a shop-vac hose down there so it was resting on the lip of the 4" pipe, and turned it on for a couple of seconds. Then I disconnected the hose from the shop vac and could definitely smell the odor from it. Repeated this 3 or 4 times to verify, and got the same result each time.

So I'm fairly sure the smell is escaping from the gap where the smaller pipe exits the larger one, which is probably bad.

What would my next step be? I know from here on out it could get hideously expensive if they have to start digging up the floor. They've mentioned cameras etc. but I'm wondering if there's any specialist equipment (gas analyzer?) that I should specifically be asking for.


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## Thurman (Feb 9, 2009)

"The 2" vent pipe enters an open 4" pipe just above floor level. It's pressed against one side, and has pieces of wood wedging it in place on the other side." 
IF the 2" vent pipe is vertical and goes into the 4" pipe then it appears you have found your problem. IF it were a horizontal run I would expect you would have noticed water leakage. Without a picture (although a good description) I would say you have sewer gases escaping from the gap between the 2" and 4" piping. Depending on what type pipe(s) you have there you should be able to connect the two together with a "Fernco" style coupling that fits each size pipe. Good Luck, David


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## JDC (Mar 11, 2008)

You're saying the 2" and the 4" pipes dont make a solid connection???? 
Let me get my head to stop spinning.....
The 2" enters an open end of the 4" and is just wedged in there?
Whomever did that should be beaten severely about the head and shoulders with a dirty sock pulled out of a clogged toilet.


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## Thurman (Feb 9, 2009)

JDC: This was the same as my initial reaction to his statement, but I felt he had enough troubles already. "aaronb9" has stated that he has already had "plumbers" out to investigate this problem and they had not found it, the homeowner found what appears to be the problem. Hopefully the homeowner is an adept DIY and can fit some type of coupling onto these two pipes. I am not recommending this, but at this time duct tape would be an alternative to what he has. Good Luck, David


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## aaronb9 (Sep 2, 2009)

Sorry guys, I didn't explain that part very clearly. As best we can tell, the 4" pipe isn't actually 'used' in the drain system, although it appears to be drain pipe it's acting more as a conduit from what I can see.

I know the house is built on a concrete slab, although I'm not familiar enough with building practices here to know whether or not all the plumbing is encased in concrete, or whether it sits in the dirt below the slab.

If it's the latter, this 4" piece of pipe seems like it's set into the concrete, and the 2" pipe just passes through it. Both pipes are set vertically.

At least I hope this is what's going on. The smell has been gradually fading over this past few days, but it hasn't rained at all which could explain it.

With that said, the source of the odor did appear to be the gap between the pipes. My hope is that it was just residual but I guess we'll see once it rains heavily again.

Thank you all again for all the advice and information, it's very much appreciated.


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## plumber Jim (Mar 30, 2008)

Can you post a picture of that pipe in the wall?


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## aaronb9 (Sep 2, 2009)

Sure, to describe the orientation of these photos: Facing the sink, the wall directly behind the countertop now has a hole in it. These were taken by putting the camera into the hole, and pointing it down towards the ground. The first one shows the floor in focus, the second shows the vent pipe/sink drain in focus.

My dimensions are a bit off too I think, the smaller pipe is 2", the larger one must be about 3".

The ground does look wet, next to where this pipe enters the floor, but I'm absolutely sure that it's not - it almost looks like some kind of sealer or varnish that appears shiny.

here's the links to the photos:

http://img180.imageshack.us/i/drain1.jpg/

http://img143.imageshack.us/i/drain2.jpg/


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## plumber Jim (Mar 30, 2008)

It sure looks like the larger pipe is just a sleeve through the concrete.for fun can you stuff a rag in the space between the 2" and the 3"? then see if you still smell the odor.


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## cm3putter (Sep 9, 2009)

The quickest way to detect the leak is to smoke test the drain line from just outside your house. I know that sounds like a big deal but it's actually very simple IF you know where your clean-out fitting is outside the house. Any big box hardware store will have the non-toxic smoke packs. You blow the smoke with a small fan into the clean-out fitting (make sure and plug the "downstream" side of the line, and the smoke will show up at any leaks in the vent pipes.


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## cm3putter (Sep 9, 2009)

I agree with plumber Jim, the 4" looks like a sleeve, but could still be the source of the odor if the 2" is leaking under the slab. I'd start by using spray foam to seal that area between the 4" and 2" pipes.


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## aaronb9 (Sep 2, 2009)

cm3putter said:


> The quickest way to detect the leak is to smoke test the drain line from just outside your house. I know that sounds like a big deal but it's actually very simple IF you know where your clean-out fitting is outside the house. Any big box hardware store will have the non-toxic smoke packs. You blow the smoke with a small fan into the clean-out fitting (make sure and plug the "downstream" side of the line, and the smoke will show up at any leaks in the vent pipes.


The second plumbers that came out did run a smoke test, but they did it on this vent pipe where it exits the roof. We didn't see any smoke coming up through the gap though. The idea of smoke testing from the cleanout sounds like a good one - as far as I know we have one cleanout where the main drain line heads off toward the street, and presumably the sewer.

How penatrative is the smoke usually? If the 2" is leaking under the slab and the odor is coming from contaminated ground, is the smoke likely to make it through?

Are there any tests I could do to confirm or rule out whether or not the 2" pipe is leaking under the slab? The shower in this bathroom gets run twice a day, sinks and toilet are run/flushed several times too with no apparent effect on the odor.

The weather has been dry and sunny here for about a week now, and the smell has pretty much gone.


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## cm3putter (Sep 9, 2009)

The smoke is very dense and will show up if there is a cracked pipe, etc. Just make sure and plug the downstream (or street side) of the drain line before testing. Also, probably unlikely, but you might first call your water/sewer company and see if they will come out and smoke test the line for you. Most places won't but I've encountered some companies will. 

I'm not aware of any "easy" test that you can conduct to confirm a leak. (the smoke test will confirm you have leak somewhere, but not pinpoint it if smoke shows up in that sleeve). A "hard" test would be to isolate the line (somehow plug it on both ends, don't know if that's possible, and probably not practical) and pressure test it with air or water. If it won't hold a constant pressure then you definitely have a leak.


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## plumber Jim (Mar 30, 2008)

can you poke something like a stick or something down between the 2" and 4" and see if it come back wet? that way if you find its wet you might have a peaking drain pipe below the slab.


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## aaronb9 (Sep 2, 2009)

I probably can try and get something down in the gap actually, space is pretty tight with the cabinet still in place but I'm sure I can figure something out.

It's supposed to rain most of the weekend, I'm hoping that'll show up the problem if it's still there. As of right now the cabinet still smells fine.


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## Ladderpouch.com (Sep 11, 2009)

Yes , a picture would definitely help the cause.


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## aaronb9 (Sep 2, 2009)

Well it finally rained heavily this evening, and the smell came back very strongly. I am almost positive that the sleeve pipe is the source.

I was able to drop a rod into the sleeve, with a piece of tissue paper on the end. It dropped maybe 8-10" before it hit the ground, and the tissue paper came out dry. Tried it a couple of times with the same result.

I don't think I can get good enough access to block off the sleeve with a rag or expanding foam etc, at least without pulling the cabinet out and cutting away the drywall.

I removed the cap to the main cleanout this evening too, this is located outside the front of the house, and I think it goes out to the main sewer in the street. I couldn't smell anything there, so assuming I have the layout correct I don't think it's main sewer gas backing up into the house.

The outside ground the other side of the wall was very wet again, if I stepped right next to the slab my foot would sink a little and the water would rise halfway up my shoe. The rest of the grass was wet, but even at a point where the water combines and runs off the roof it wasn't this wet. 

At this point I've spent $500 on plumbers, neither of who diagnosed it correctly or fixed it in the slightest. I'm wondering how much more diagnosis I can do myself (even if it's destructive) or whether I should just try to find another plumber.. If I end up going that route, any tips on what I should specifically ask them over the phone to try and get someone who really knows what they're doing?


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## Wildie (Jul 23, 2008)

As an electrician, I often used duct seal to close off a raceway, that had cables and conduit running in it.
Its similar to a childs 'plasticine'. or even window putty. Only it never hardens.
Its carried by most electrical supply outlets.
The space inside the 4" pipe should be sealed with this product!


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## aaronb9 (Sep 2, 2009)

Thanks for the tip, my only concern with sealing it off would be if it causes the smell to collect and appear somewhere else. Right now the 'source' is clear and it mainly affects the adjoining closet.

Is it possible this could happen?

Some more information too: I pushed a pipe into the ground outside, about 4" away from the exterior wall. The ground seems to be dry several inches down, but is very wet for the top few inches. Right next to the wall I peeled a bit of grass back, and could immediately smell the same smell. As soon as lowes opens I'm headed out to buy a spade and see if I can find out any more.

I also removed the toilet in that bathroom last night. I noticed when the plumber refitted it from the snaking several months back, one of the two plastic studs that holds it down had broken off so it was only secured by one side. With that said, I cleaned off all the wax and looked down the drain with a mirror as best I could. I didn't notice any odor at all from this line either.

What's got me most confused now is why this smell would be so strong through that sleeve pipe, but neither the main line cleanout nor the drain under the toilet seemed to smell at all.





I dug some holes outside today, two against the house wall and two futher away. The two closest the house had water pooling in them at around 18" deep, and a slight sewer gas smell. I dug one 10' from the house to 22" deep but no water or smell was present there. I dug the last one downhill from the house, and there was water pooling in it at around 8" but no odor at all.

I was putting up a light fixture in a different bathroom today, and also noticed the same smell from inside the wall cavity which is definitely new. I'm also fairly sure it's present under the kitchen sink now too. It's permeated the whole house again like it did last time it rained, so it's getting harder to pinpoint it.

I'm kind of at a loss now on how to proceed.


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## Wildie (Jul 23, 2008)

aaronb9 said:


> Thanks for the tip, my only concern with sealing it off would be if it causes the smell to collect and appear somewhere else. Right now the 'source' is clear and it mainly affects the adjoining closet.
> 
> Is it possible this could happen?
> 
> ...


 Are you connected to a municipal sewage system or using a septic tank?

Septic tanks need to be pumped out, from time to time. If they are not, they eventually fill up with sludge, then they quit functioning. 
Raw sewage then flows out to the weeping bed and plug this up.
If this happens, untreated effluent runs into the ground all about.
It seems likely that this could be your problem, and the methane gases from untreated sewage is finding its way into your house!
Where I live, home vendors are required to devulge problems of this nature and if they fail to do so, can be sued for the cost to make repairs.


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## aaronb9 (Sep 2, 2009)

We're on the city sewer system, no septic tank.

That's definitely the kind of problem it seems like though.


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## Wildie (Jul 23, 2008)

aaronb9 said:


> We're on the city sewer system, no septic tank.
> 
> That's definitely the kind of problem it seems like though.


 If they put in a sleeve for your bath sink, its likely that there were sleeves installed for everything else.
I would suggest that you would check all your drains and if they are run through sleeves, that they would be closed off with duct seal.
Perhaps you could find someway to vent under the slab as well.

Its conceivable that your sewer line is damaged and allowing sewer waste to run into the ground. Or even allow sewer gases to get under the slab.
My neighbor had a problem with his sewer and the plumber installed a trap and a vent at a point before it enters the house.
It may be a good idea to have a plumber look down your sewer with a TV camera and check for damage!

As an after-thought, all your sinks and toilets do need to have venting to the roof! Make sure that you do have this!


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## aaronb9 (Sep 2, 2009)

All except two have roof vents, the other two have 'studor' vents. The one where the odor seems strongest has roof venting.

I bought two new studor vents to install, and plan on checking all the other roof vents for blockage. No drains are draining slowly, but an upstairs toilet does cause some thumping noises from the pipework when flushed.

I'm not too familiar with the typical plumbing layout of a drain line, would it be typical that it uses mostly 4" pipe below the slab and the 2" pipes connect to this as early as possible? The house is 3 years old.

I ask because the plumbers I've called seem to be equipped with cameras that'll fit a 4" line, but not a 2" line. They've also told me that unless the pipe is basically destroyed, it won't be visible on camera. Is that right or should I try asking some more?

I didn't realize you could get a trap installed in the main sewer line, that could be well worth a try too, thanks for all the help!


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## Wildie (Jul 23, 2008)

aaronb9 said:


> All except two have roof vents, the other two have 'studor' vents. The one where the odor seems strongest has roof venting.
> 
> I bought two new studor vents to install, and plan on checking all the other roof vents for blockage. No drains are draining slowly, but an upstairs toilet does cause some thumping noises from the pipework when flushed.
> 
> ...


 My hunch is that all the under slab plumbing was roughed in before the slab was poured. Where the plumbing enters through the slab, I would assume that they installed a 4" sleeve to contain the wet cement from contacting the plumbing lines. Usually these sleeves are just long enough to contain the cement as it is poured and finished. 
I would expect that you would find such sleeves at any point where the plumbing passes through concrete.
These sleeves are likely a 'code' requirement.
I doubt that you have a plumbing problem. I would bet that because of your high water table that its more likely ground source methane that you smell.
If I were installing electrical conduit through a sleeve, I would be required to close the sleeve off with duct seal and this is what I would do next.
The duct seal compound is relaively cheap and well worth trying. Even if it doesn't work, it will cause no harm and may be beneficial.


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## cm3putter (Sep 9, 2009)

that's correct on tv-ing the line, most plumbers won't have a camera that will tv pipes smaller than 4 inch's in diameter. Just in case you do have someone tv the 4 inch line, try and do it when the water table is up and their is no sewer flow in the pipe. Pressure from the water table will penetrate into the 4 inch pipe if there are cracks.


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## aaronb9 (Sep 2, 2009)

I went up on the roof yesterday to try and snake all the cleanouts, just in case. I haven't tried sealing the sleeve yet because that'll require pulling the cabinet out, which is going to make a heck of a mess (it's attached/caulked/glued? to the wall, and so is the countertop & backsplash). I'll definitely be doing that at some point, I just want to exhaust all the easier ideas first.

The cleanout to the upstairs bathroom (not the one with the odor problem) was loose, so I went into the attic and found that it makes a 90 degree bend, made up of 2x 45 degree couplings. Each coupling was cemented to it's respective pipe, but where one coupling joined the other there was not a sign of any PVC cement, and the pipe was completely out. I cleaned and cemented that join, but it didn't seem to be the (only) problem. The sprinklers ran this morning and made the smell in the downstairs bathroom a bit stronger again. I didn't smell anything in the attic that would suggest it was the source (different sides of the house too).

I also replaced the two 'studor' vents in the house with new studor parts, and used teflon tape, mainly to rule them out.

As far as testing the drain line under the slab, no plumbers I've called have mentioned this to me yet, but I'm wondering how safe a pressure test would be. As I understand it they cap off the vents, block off the main sewer line and pressurize the drain (presumably with air?). You then flush one toilet and the water level supposedly rises in the bowl, and should stay that way for a couple of hours if there's no leaks. I'm wondering whether to try and find someone who can do that.

I've been trying to read up on the ground source methane but haven't found much that's helpful. It definitely sounds like a plausible explaination, I'm wondering why I wouldn't smell it throughout the whole yard though (I dug same depth holes just 10' from the house and smelt no trace).

Based on what I've now seen of this houses' plumbing, I'm worried that a joint may have been done poorly under the slab, and the snaking a few weeks back knocked it loose.


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## aaronb9 (Sep 2, 2009)

I looked in the main cleanout again today, and noticed it seems to have a ~1/8" green sleeve in the vertical section. As I was tightening it down, I saw the outside start to rotate as well. I wasn't yet able to see if it was the whole vertical section or just the screw cap though.

Is this sleeve normal practice, or is it likely to be one of those repair solutions? It's only on the vertial part.

I also went up in the attic right above the offending bathroom, and couldn't smell a thing. I will pull the soffet down tonight and confirm that it's not a vent leak, then I guess at least I know I'm looking at a ground methane issue or an under-slab drain leak.

I'm still having no luck finding a local professional who specializes in this stuff unfortunately.


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## aaronb9 (Sep 2, 2009)

I had a leak detection specialist come out today and it seems like we don't have a leak in the drain line. He put an inflatable plug in the main drain line, and ran the water until it just started backing up into the shower. Marked the water line on the shower floor, then left it 30-40 minutes after which it hadn't budged at all.

So right now it's looking like it's ground source odor. Now we've hopefully ruled out a pipe leak, pulling out the vanity seems like the logical next step.

Thanks again for all the suggestions and help.


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## Wildie (Jul 23, 2008)

aaronb9 said:


> I had a leak detection specialist come out today and it seems like we don't have a leak in the drain line. He put an inflatable plug in the main drain line, and ran the water until it just started backing up into the shower. Marked the water line on the shower floor, then left it 30-40 minutes after which it hadn't budged at all.
> 
> So right now it's looking like it's ground source odor. Now we've hopefully ruled out a pipe leak, pulling out the vanity seems like the logical next step.
> 
> Thanks again for all the suggestions and help.


[Post 22]

* I doubt that you have a plumbing problem. I would bet that because of your high water table that its more likely ground source methane that you smell.*


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## aaronb9 (Sep 2, 2009)

Oh yeah, I know a couple of you guys called it several posts back, I was holding off on this puely because I can't get to that sleeve to plug it without removing the sink, countertop, possibly baseboards and pulling the whole vanity off the wall. Hope I didn't give the impression that I was asking for advice then ignoring it.

Now I know my plumbing's supposedly good, it's demo time!

The plumber also recommended using something along the lines of concrete or plaster, but I'm thinking if we do that and the slab settles or moves, we risk causing a leak. The electrician's putty is going to be what I use if I can find it.


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