# Mystery wet spots on living room floor



## robertcdf (Nov 12, 2005)

Sleepwalking child who decides to pee on the floor? I don't know, I'm just reaching.


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## joecaption (Nov 30, 2011)

Pictures please.


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## Missouri Bound (Apr 9, 2011)

Pull up all of the "handy panels" There is no way that is adequate for any subfloor. You need 4 X 8' sheets. What is that over, just floor joists?


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## sweaty (Jul 18, 2008)

I had that happen once. There were pinhole leaks in a pipe behind a wall. The water worked its way around and showed up on the carpet.


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## kwikfishron (Mar 11, 2010)

Is there a light fixture above that spot?

Post some pictures of the entire area, inside and out.


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## creeper (Mar 11, 2011)

If not the light fixture then him


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## littlecabbage (May 11, 2012)

*Pictures now*

No kids, no pets, no light fixtures, no pipes anywhere near the room. 
All pipes are in the basement, and none run under the living room. Only the supply runs under that side of the house, but it's under the other room. And it's not leaking anywhere. So a pipe leak is out.

The panels are not actually the sub-floor. Sorry, that was inaccurate of me. They are covering the former hardwood floor, and underneath that are 2x8 joists. The hardwood floor was ruined cosmetically, but not structurally, in the fire that happened about 50 years ago, so they basically laminated it with these handy panels and put carpet over it.
When i noticed the floor was very wet, i pulled up a panel to see what exactly was underneath. Found the hardwood floor, and even though water had seeped all the way through the plywood panel, the hardwood was dry.

The pics below are from when i first pulled up the carpet. In the 1st you can see its position to the front door, and the 2nd one was taken from the front door. They were dry when the picture was taken, even the darker spots were not wet- just discolored. But once in a while they turn dark brown and feel damp to the touch. There's never been any standing water, but the dampness takes several days to go away with nothing covering it. I'm in NJ. We've had a damp spring, but it's not like southern humidity or anything. I'm getting a dehumidifier today, but i'd sure like to know the source!
Thanks!


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## CaptRandy (Nov 9, 2011)

infloor baseboard water heat with tubes running under the sub floor?


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## kwikfishron (Mar 11, 2010)

Interesting…I’m at a loss and chasing mystery leaks is about half of what I do.

Amazing how the stains seem to follow the traffic pattern from the front door around some furniture and straight into the kitchen.

It looks what my place probably would if I tore up my carpet after years of coming through the door dripping wet. :wink:


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## cortell (Nov 27, 2010)

Here's a theory. You have very high humidity in the basement (probably because of foundation issues). Your basement isn't insulated and it's not heated; it gets very cold in the winter. You keep your living room nice and warm in the winter. These conditions could potentially lead to a lot of condensation in the subfloor/hardwood/panels combo you've got going there. 

Buy a hygrometer and keep tabs on the humidity down in your basement. If you're in the 40% area, that's about as good as you can expect. 60% is bad. 80% and higher and you've got a very serious problem.


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## littlecabbage (May 11, 2012)

I forgot to mention the basement is completely waterproofed. The house was empty for a year and a half before i looked at it to buy it, and my first visit was after the wettest summer on record here. There was not a drop in the basement, or any sign of mold or mildew. 
That being said, despite the incredible waterproofing job, there is some humidity. But if it was coming up from the basement, wouldn't there be signs of water damage on the hardwood floor?

I'm glad i'm not the only one perplexed by this. I was wondering if there was something i was missing, or if someone knew more about the absorption properties of plywood thanb me


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## Missouri Bound (Apr 9, 2011)

littlecabbage said:


> I'm glad i'm not the only one perplexed by this. I was wondering if there was something i was missing, or if someone knew more about the absorption properties of plywood thanb me


WEll you are definately missing something, but all of us are. Start pulling up all the wet boards and tell us what you find. And what's the humidity in the house and the basement?


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## Missouri Bound (Apr 9, 2011)

drfyjhg57 said:


> Thanks for sharing.


 
What the does that mean?


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## cortell (Nov 27, 2010)

cortell said:


> Here's a theory. You have very high humidity in the basement (probably because of foundation issues). Your basement isn't insulated and it's not heated; it gets very cold in the winter. You keep your living room nice and warm in the winter. These conditions could potentially lead to a lot of condensation in the subfloor/hardwood/panels combo you've got going there.
> 
> Buy a hygrometer and keep tabs on the humidity down in your basement. If you're in the 40% area, that's about as good as you can expect. 60% is bad. 80% and higher and you've got a very serious problem.


Well, you got me. Good luck finding the source, and please update us when you find it! This is quite the mystery.


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## Gary in WA (Mar 11, 2009)

1. What type of heat source, forced air?

2. Does the front door have gaps in the weather-seal around/under it?

3. Was the wood strip flooring damaged/missing under the spots on the plywood?

4. Are there furnace/HVAC ducting under the spots in the basement?

5. On the plywood you removed, was the wet worse on the top or bottom side?

6. Are the floor cavities insulated under the living room at all?

Gary


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## gottlm (Apr 28, 2017)

Help! I'm having the exact same problem as OP.
If anyone has any additional info since this post was last active I would appreciate it!
Almost every detail as he describes is the same in my case.
Thanks!


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## NotyeruncleBob (Mar 9, 2017)

Water moves, or flows, until it hits an obstruction and then changes course. 
In the OP's case it looks like it could be coming from the front door with enough volume that it is flowing down the joist and could be making a turn at some blocking or other support. 
Water moves with gravity and doesn't need much to move. If it's sitting on something porous like a sponge, or wood, it will move through that too. 
Get down there and track it back to the source. Fix that water intrusion at the source!


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## Kimberlylee (May 26, 2017)

I found this post because I have the exact same problem and was looking for a way to get rid of it. But I know EXACTLY what it's from, so maybe this will help someone.

It isn't a leak.

A couple years ago I pulled the carpet up in my dining room and had area almost exactly like the pic the op posted. Cleaned it with everything I could think of, mopped with bleach, etc. It would dry, but every time it got humid outside or rained the spot came back. Drove me crazy. It did eventually stop. Like after a year (yes, I lived with plywood floors for over a year-yuck!)

Well, a month ago I pulled up the carpet in my family room. The reason I pulled it is because the dogs were peeing on it in the same place all the time and it smelled awful. And now I have another mystery spot. Right where the dogs were urinating.

What it is: the dogs kept pissing in the same spot, we cleaned it up but not enough to get it all up apparently. The wet got under the padding and never had enough air circulation to dry fast enough so the plywood soaked it up. Running over it with a carpet cleaner probably didn't help the damp either. Now that I have removed the carpet and padding, the plywood (which is wet INSIDE) is trying to dry out.

"But I don't have pets" you say. At some point somebody spilled something or you used too much water with the carpet cleaner or whatever and that got under the padding and was never able to dry out. Now it's seeping up to the surface as it dries.

Now if I could figure out how to get it to dry?


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## mikegp (Jul 17, 2011)

Put a table or some raised plywood above the spot so you can rule out any drips from above.


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## KarK (4 mo ago)

littlecabbage said:


> I'm renovating a little rancher. In Janurary, i pulled up the living room carpet and noticed some old water stains on the plywood subfloor (1/2" 2x4 handy panels on top of the old hardwood floor, which had been damaged in a fire some 50 years ago) The stains were dry so i didn't pay much attention to them.
> In February, one day very suddenly, the spots were wet. I found no leaks in the roof, and the ceiling and attic insulation were dry. There are no pipes underneath the floor, either, and the stains are nowhere near the windows.
> The spots dried after a few days, and since my roof wasn't leaking, i put it out of my mind again.
> But once in a while, the spots would somehow re-wet themselves. They show up in the same places and patterns every time. It usually happens when we've had, not a heavy rain, but a few days of drizzly weather and high humidity.
> ...


I am having the exact problem and feel quite certain it is related to the fact that I'd had the dogs' water bowl in that area for a long time and it not only would wet the plywood underlayment regularly but that it somehow altered the plywood in such a way that it is just prone to wanting to pick up any moisture in the air. It's so weird that it just stays contained to the pattern it is in and even when the moisture meter shows it's 100% wet the pattern doesn't change i.e. it doesn't flow into other areas of the plywood. That is one of the reasons I think the plywood is somehow chemically altered. 
The one thing I can dry out the wetness with is a hot hair dryer but it only stays dry for an hour or so and then fills up with water again. 
It's so bizarre and I'd really like to get a scientist on the problem. Anyone know someone?
If it WAS altered I would think that just removing and replacing that portion of the plywood would work.
Has anyone with the problem tried this?
I'm hoping after 9 months of having no kitchen to soon lay a vinyl floor but I need to dry it out before then as I certainly don't want mold down the road. 
Please, anyone who has had this problem, I would love to hear from you to know if you resolved your own by somehow drying it, replaced that section or plywood, or just decided to ignore it and carry on hoping it wasn't a mistake to do so.
Thanks for anything you can share!


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## chandler48 (Jun 5, 2017)

@KarK This is a 10 year old thread. It is always best to start your own thread, possibly referring to the older one. You will garner more information if you were to do that.


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