I recently noticed some white crusty stuff on all the edges of the LVP in my master bath, water closet, wife's closet and a step in to our bedroom. I work away so wasn't able to deal with it. It almost seems worse this weekend when I am home and it has me worried. What could cause it? It sure seems like it could be water up under the LVP working its way up. My wife also recently has a neoprene bath mat in the bathroom and water seemed to stay under it and no where else which didn't make sense. Is this a sign of water being under the LVP? I'm not sure what other signs to look for. There doesn't seem to be much else like soft drywall or bad looking baseboards. I will try and take up a piece or two of the floor to see if I see water this weekend, but I'm only home on a whirlwind trip. I am pretty worried though.

Appreciate any input.

I reckon it could be from hard water and the cleaner doesn't do the best job? I looked behind shower at bottom of shared wall and no sign of leaks.

Just a thought - assuming your wife's closet is carpeted, can you pull up a corner close to the shower and see if there's any signs of water? Maybe even for a few hours after a long shower? We discovered a shower pan leak on the carpet side of our shower in an adjacent closet

It is LVP and I looked back there and don't see any signs, including the white in the joints of the LVP. On q side note that is the first time I've ever seen that GFCI

Sea Speed said:

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It is LVP and I looked back there and don't see any signs, including the white in the joints of the LVP. On q side note that is the first time I've ever seen that GFCI

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Dude, your place looks nasty!

It is just scuffed paint in a spot that a small dresser goes in alow little cubbyhole of a closet. Looks can be deceiving. Painting my wife's closet isn't exactly a priority. Could it use some dusting? Probably.

Idk, it's probably nothing, but if I were in your shoes, I would also want a look under a couple of the planks. Is it a slab underneath, or 2nd story/pier & beam?

Not sure what kind of underlayment is used for LVP in this case. There was another thread a few months ago where water damaged the underlayment for LVP, but I'm not sure if that's typical.

Yea I'm going to pull up a couple by the sink and see what I find. Its first floor on the slab with some tbin blue colored underlayment but dont recall any specifics. I just can't imagine what it is from at all and why it is only focused in the master bath area and isn't in any of the other bathrooms that get more water on the floor from kids baths.

I think that gfci is for a whirlpool tub, or was at some point.

Yea we have one we plan to rip out when doing next half of bathroom renovations, just had not seen this before. The switch for the tub is all the way on the other side of the room and there is about 6 feet if wall to go along to get here. Not what I expected to find back there.

Sea Speed said:

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On q side note that is the first time I've ever seen that GFCI

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Do you have a jetted tub? If so, the GFCI likely feeds that. This is a common configuration to prevent someone from having to disassemble the tub surround to reset a GFCI on the pump outlet.

Yes we do, and that backs up MBL said earlier. Still worried about this issue from OP though.

Google "White Line Syndrome" (i.e., planks shrink and stretch the waterborne polyurethane coating). It seems to be one possibility.

Bump for weekday folks.

Just an idea, but maybe put a piece of white printer paper down where you suspect water. If the paper gets wet, it will show and you will know. Maybe weight the paper down with something so you know you have good contact, but not something flat like a book. You want to make sure the paper can warp a little if it gets wet. Maybe put some shoes on it or something like that.

I just can't figure out what else it would be. The thing that makes me think water is the issue with the bath mat. I should get a chance to pull up a piece of flooring tonight.

We're considering LVP and have a friend who has had a lot of trouble with his. Did you ever figure out what was causing the white stuff?