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Mysterious Wet Spot on Wall

5001 Views 6 Replies 3 Participants Last post by  DBB1
I'm doing a bit of a remodel in a powder bath, and plan to tile previously wallpapered walls. I stripped the wallpaper using a chemical remover.

When I removed the baseboards, I noticed a small wet spot about the size of a quarter in the drywall, about 4" below the water inlet for the toilet. At the time, it looked as if some of the wallpaper stripper had run down behind the baseboard and had been sitting there on the room side of the drywall.

A day or two later, I'm priming the wallboard, and I notice that the "wet" spot is still there. I enlarged the opening around the 1/2" copper inlet pipe, and inserted my finger to feel around. I could detect no moisture whatsoever anywhere on the pipe, or anywhere around. Nor is there any dampness or moisture at the bottom of the wallboard.

Could it take that long for drywall to dry out, if in fact the spot was caused by the wallpaper stripper? I would think that, if water had been leaking, I would have seen mold or something, or at least the softening of the wallboard from long-term exposure to moisture.

Any ideas?

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If you are certain that the spot is not from water---I'd prime it and move on---it might be an old oil stain from years ago----Mike---
Well, it feels damp, and came back through the primer. Problem is, I'm not sure if it is water, or just something that just recently soaked into the drywall.

If this was a leak coming from somewhere, I would have to assume that it's been doing that for a while - wouldn't I see some mold, or something?

I'd hate to ignore it and tile over it, then down the road have to rip it out and deal with a bigger problem.

I think I'll start my tiling job; it will be a bit before I work my way around to that spot. Maybe by then, it will have dried out. If not, I guess I should play it safe and call a plumber... Bummer.

If it feels damp open the wall and find out where it's coming from----I've had the pleasure of discovering trim nails driven into water lines---and opening up as I worked near by--find the leak.
Post a picture-----
Yep, I've seen where a trim nail was shot into a water line and didn't leak until the nail finally rusted off. Then there was a huge mess....
Well, it seems to have dried up over the period of several days. There's just a slight stain where it was, so I'm going to chalk it up to wallpaper remover that ran down behind the baseboard. I was really concerned given its proximity to the water inlet. Drywall must take a while to dry out.

I ran my finger over the pipe as far as I could inside the wall, and the stud the pipe is against, the nail plate toward the other side of the interior, and the pipe itself are still dry as a bone, so maybe I got lucky.

I'm moving on and tiling over it...

Thanks everyone, for the replies.

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