Need help with preventing bubbling paint for old house bathroom

Problem Description:

The house is old early 1930s. Walls are plaster on rock lathe board (metal lathe reinforcing the joints between ceiling and wall), then studs, probably some paper, air gap then red brick exterior walls. The porcelain bath tile is the old thick style and extends up to 48 inchs around the room and then up to 6 foot in the tub area. Above the tile is the plaster wall. Several spots on the wall are bubbling as well as the painted ceiling over the tub. The ceiling is also cracking and has some plaster bulges.

This bathroom has a window that does swing open, it has the original steel framing There are two fixed panes on the top.

The bathroom is on the second floor and has the kitchen below it and the floor above it is basically a finished attic bathroom. Maybe 2-3 feet of the bathroom outer edge has only roof above it based on the roof slope and position of attic bathroom.

What to do:

I can't get my family on board with cracking the window a bit during showers so... My best guess is to install a fan to be used when taking showers. The best guess location for said fan is in that 2-3 foot segment that is covered the roof. I probably have to replace the whole ceiling over the tub but haven't found good options for quiet wet area bath fans. Then my biggest issue is getting some power to that fan.

I wanted to ask the GRM there is another way to get this done. I don't want to use the desiccant products as the kids get to curious.

There are better paints, namely marine types. But if the substrate is damp, the best paint in the world won't fix it.

As for fans, consider the controller. Namely humidity detecting automatic controllers. Sadly, I do not recommend this one. Leviton Humidity Switch

Fan with automatic controller is the best and probably only effective way to solve this problem.

When we bought our house the bath was very similar (tile and all) to yours. It had a window but no exhaust fan. And we had a moisture problem.

We ended up installing a fan that we use all the time. Some day we will get an automatic controller but since the wife is the only one that uses that bathroom now it may be a while.

is replacing the bathroom light fixture with a fan/light combo an option?

keep your existing switch and wiring, run both the fan and light at the same time, all the time. just make sure you are ok with the wiring and the power you are going to draw.

In reply to failboat:

I have one in my bathroom that fit into a recessed light opening. It does a good job of keeping my windowless bathroom dry.

failboat wrote: is replacing the bathroom light fixture with a fan/light combo an option? keep your existing switch and wiring, run both the fan and light at the same time, all the time. just make sure you are ok with the wiring and the power you are going to draw.

This old bathroom does not have any lighting in the ceiling. Only two fixtures on each side of the inset medicine cabinet/mirror over the sink.

Getting power to a fan is one of the big issues. I kind of won't know what to do until I cut some holes.

Hal wrote: Fan with automatic controller is the best and probably only effective way to solve this problem. When we bought our house the bath was very similar (tile and all) to yours. It had a window but no exhaust fan. And we had a moisture problem. We ended up installing a fan that we use all the time. Some day we will get an automatic controller but since the wife is the only one that uses that bathroom now it may be a while.

How did you get power to it? Pre existing light location?

The attic bathroom is essentially unused though it is in original state and functional. My only thought was to see if I can punch a hole in the outside wall and see if I can drop down power from somewhere in the attic.

You don't have an access door in the attic to that little triangular cavity?

Being built in the 30s you might have "balloon framing" you can drop a wire straight down the wall all the way to the basement if that's the case and it hasn't been insulated at some point.

Advan046 wrote:

Hal wrote: We ended up installing a fan that we use all the time. Some day we will get an automatic controller but since the wife is the only one that uses that bathroom now it may be a while.

How did you get power to it? Pre existing light location?

Could have done that but I wanted it closer to the tub/shower. Fortunately the house is a rancher with easy attic access and nothing up there.

Balloon framing? HMMMM I will have to look into that.

I was thinking to try to run a conduit from the attic to the basement inside the wall. That way I can run power up from the panel up that conduit. That would be four stories and not sure I can make a straight drop without hitting something along the way. The kitchen is the big one as it too has the thick tile walls.

Ugh sounds like a major project. I think that three bathrooms (Basement, 2ndflr, attic) share the same wet wall. The basement and attic bathrooms are not really used. Maybe worth gutting both attic and basement to minimize impact to the Kitchen and much used 2nd floor bath.

IDK seems like too much project for now.