Weird water bubble in paint

[andyvh1959]

I remodelled the main bath in our 1973 built home back in 2018. Added a shower where previously was a bathtub, so there is a lot more water use in there since 2018. I repainted the walls with Behr interior paint, applied over the cleaned previous paint on the walls. Two sinks on the vanity, like before.

My wife's sink is nearest the door. Over the past year, above the door a bubble developed on the wall. I thought it was just paint peeling for whatever reason. Well, I pricked the bubble and out came about a meauring cups worth of water! The wall is solid behind the bubble. The Behr paint that had bubbled is very elastic. Above the bathroom is a loft directly under a shed style roof. No water penetration up there that would have leaked onto the area above the bathroom door. The vent line for the sinks/bathtub/toilet is away from the area over the door. No water trace or trail anywhere. Near I can figure is the Behr paint was porous enough in one spot that water/condensate could eventually accumulate, lift the paint and create a bubble. Wierd.

 

[PCustoms]

Ice damn or insulation air leak in the area?

 

[Chaznsc]

Every bubble I’ve seen in paint has been due to a leak of some sort.

 

[mepstein]

Water travels. It’s coming from somewhere.

 

[atomicpunk]

In an apartment I lived in bubbles appeared in the wall paint of the steps out, they were full of water. Above the steps was a closet with the water heater in it that had started leaking.

 

[andyvh1959]

Nope, no ice dam. Area of the roof above the loft, above that area of the bathroom is nearly on the center of the roof section. There is nothing on the roof in that area. The floor of the loft, somewhere above that part of the bathroom would be wet, somewhere. Or, the water would have to enter the attic area next the loft, then travel across the top side of the bedroom and hallway ceiling across from the main bath, and then migrate to the wall just above the bathroom door. There is no evidence of water on the hallway or bedroom ceiling.

BUT! I was doing my business on the toilet and looked up to the ceiling exhaust fan. Depending where that ceiling fan exhausts, and since in the past few years the bathroom generates a lot more moisture because fo the shower, my guess is the exhaust run of the ceiling fan is the source. Loft is directly above the bathroom, so the ceiling fan, IF properly ducted, must have a run of ducting that goes over the bathroom door. So up to the loft attic I go to see how the ceiling fan exhausts, or doesn't exhaust. I've been in this house since 2002, pretty sure the ceiling fan is original to the 1973 house. On to another project.

 

[PCustoms]

Nope, no ice dam. Area of the roof above the loft, above that area of the bathroom is nearly on the center of the roof section. There is nothing on the roof in that area. The floor of the loft, somewhere above that part of the bathroom would be wet, somewhere. Or, the water would have to enter the attic area next the loft, then travel across the top side of the bedroom and hallway ceiling across from the main bath, and then migrate to the wall just above the bathroom door. There is no evidence of water on the hallway or bedroom ceiling.

Well it came from somewhere.

There's a possibility, probably small, that you have high humidity condensing and collecting under the paint and causing the bubble. That's why I asked about poor insulation,,/air leakage.

Any pics of the area?

 

[andyvh1959]

AHA! I was doing my business on the toilet and looked up to the ceiling exhaust fan, and some very minor paint faults got me thinking. Depending where that ceiling fan exhausts, and since in the past few years the bathroom generates a lot more moisture because of the shower, my guess is the exhaust run of the ceiling fan is the source. The loft is directly above the bathroom, so the ceiling fan, IF properly ducted, must have a run of ducting that goes over the bathroom door. So up to the loft attic I go to see how the ceiling fan exhausts, or doesn't exhaust. I've been in this house since 2002, pretty sure the ceiling fan is original to the 1973 house. On to another project.