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Old 02-28-2013, 12:33 AM   #1
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Wall damage below bathroom

Hey guys, i've reached my wits end with this wall leak. About 6 months ago I started to get some paint bubbling on the wall in my dining room. It eventually reached the point where it was so soft I started to open up the plaster and it appeared as it does below.

I replaced the wax ring and didn't notice any wetness whatsoever around the waste pipe or subfloor that was exposed near the toilet. Not convinced it wasn't the problem, I had a handyman help me replace the flange and wax ring again and although he didn't notice any wetness in that area, he thought maybe the toilet shutoff was leaking, so he replaced the shutoff valve and the straight pipe that attaches to it from below the tile floor. He then told me to dry out the plaster wall with a heatgun where it was wet below, mud it up, and re-paint. Well, I did that and thought the problem was solved.
A month later, bubbling paint is starting to manifest itself again on the wall below despite using killz premium primer and sherwin williams duration paint over the whole wall. Obviously i've still got a leak somewhere. I can get behind the wall of the tub, and it's not wet at all. So effectively, i've replaced the toilet seal and the tub doesn't appear to be the culprit. It seems that the sink might be the problem or some of the drain pipes that run either under my tile or behind my sink wall? It isn't wet below the sink, but I did replace the p-trap and the straight pipe that goes into the wall a year ago or so with no issues. What would be the next step for you guys if this was your problem?

Please open the attached picture for a layout of the bathroom with measurements and the other picture for the measurements of the wall damage below (before I repaired it, it doesn't look like this right now, but it's eventually going to reach this point again as it's currently starting to bubble again)
The area that is affected starts at 50" from outside wall and ends at 95" from the outside wall as seen in the wall damage picture. Directly above it, the bathtub tiled wall is against the outside wall and the tub is only about 32" wide. There is about 8" of space and then the toilet is seated and fills the 40" to 52" space from the outside wall. There is about 8" of space and then the sink goes from 60-92" of space from the outside wall.
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Wall damage below bathroom-bath-pic_w-measure.jpg   Wall damage below bathroom-wall-damage-below_w-measurements.jpg  


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Old 02-28-2013, 07:57 AM   #2
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If the hvac vent is on the floor, water can be getting through that, along the edge where the tub meets the tile floor. Only way to find out, is to cut into the ceiling and finding out where it is coming from, by looking at the sub-floor sheeting from that side. Then you can determine where the problem is, and how to fix it.


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Old 02-28-2013, 09:00 AM   #3
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Have someone go up on the roof and check the condition of the seal where the vent goes through the roof.
Often times they rot out and the leak will show up in the walls below.
Tub drains are a very common leak problum.
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Old 02-28-2013, 10:18 AM   #4
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Originally Posted by joecaption View Post
Have someone go up on the roof and check the condition of the seal where the vent goes through the roof.
Often times they rot out and the leak will show up in the walls below.
Tub drains are a very common leak problum.
+1 as first check before opening up the wall. you should be able to get a general idea if a vent stack is in that area by looking in the attic and seeing where they com out of the walls. generally, they run vertically. either way you should check all the seals on the roof to see if any are damaged.
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Old 02-28-2013, 10:25 AM   #5
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Vent and tub drain are both possible, but you are wasting your time guessing. Take out the drywall downstairs and look. This is not that big a deal compared to the goofing around you're doing in the bathroom. Actually I think this should have been done anyway - you're looking at mold issues and whatnot behind that wall. If I were the handyman you hired to look at it, I would have insisted on that. Drywall does cost money to fix but it's not outrageous, and it's easy compared to, as I said, all the other goofing around you're doing.
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Old 02-28-2013, 10:27 AM   #6
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My first thought after reading the original post would be to check the bath tub drain seal. These can leak with water in the tub or even using the shower. As mentioned, check the seals on all the vent piping on the roof.
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Old 02-28-2013, 02:39 PM   #7
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Open the ceiling and be done with it.
Look for a leak coming from the riser to the shower head.
Also pour water over the trim to the tub valve. If you get lucky a little caulking will fix a leak from the trim.
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Old 02-28-2013, 02:57 PM   #8
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When does it leak?
" Most people would rather die than think, and most do " Bertrand Russell

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Old 02-28-2013, 04:56 PM   #9
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If I understand correctly, the leak is to the right of the toilet? I'd be suspecting a rusted trap arm at the lav. Possibly where it connects to the vent stack or the 90 where it exits the wall at the lav. If it's plastic piping, maybe a nail puncture- the nail has rusted away leaving a hole. Just some thoughts...


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