Bathroom ventilation inadequate

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Winner19

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I've recently renovated my bathroom. It is about 75-80 square feet (12 feet by six feet), rectangular in size with the bathtub/shower placed crosswise at the far end of the room from where the door is.

Previously, the bathroom fan was located more in the middle of the room; however I wanted to relocate the bathroom fan into the shower and use a fan/light combination.

I installed the new fan (Air King BFQF70) at 70 cfm directly in the shower.

I also installed a new ceiling (smooth painted versus the old popcorn texture) and repainted the walls.

Upon finishing the project, we noticed within a week that condensation was accumulating on the ceiling and upper walls, and then running down the walls, leaving ugly streak marks. I tried washing and repainting the walls, then letting the paint fully cure for a week before operating the shower. Problem recurred.

I upgraded to a 120 cfm fan and while this slows the condensation process down, the streaks eventually come back.

I do like hot, steamy showers, but I've never had a problem like this before with my old bathroom set up. I feel 120 cfm should be more than adequate for this size room.

What am I missing here?

Thanks in advance for any advice.
 
Is this a first or second floor bathroom and/or is this a ranch style home? Problem could be inadequate insulation and the warm moiste air is contacting the cold surface and condensating. I also discovered the height of the shower curtain plays a role in controlling the steam.
 
My take on it, though not scientific, would be 2 issues. Having the fan over the shower draws all the condensation to that ceiling point rather than before, where most of the shower condensation stayed in the shower and you just removed less humid air from the entire room. You also have a new cold spot in your ceiling from both the fan opening and the fan housing, which could be lowering the surface temp of the ceiling, and adding to the condensation problem.
 
Is this a first or second floor bathroom and/or is this a ranch style home? Problem could be inadequate insulation and the warm moiste air is contacting the cold surface and condensating. I also discovered the height of the shower curtain plays a role in controlling the steam.

Main floor bathroom of a split level home. Attic above. About 10 inches of blown insulation. Insulation has not changed since the new fan installation.

I can try playing with the height of the shower curtain.
 
My take on it, though not scientific, would be 2 issues. Having the fan over the shower draws all the condensation to that ceiling point rather than before, where most of the shower condensation stayed in the shower and you just removed less humid air from the entire room. You also have a new cold spot in your ceiling from both the fan opening and the fan housing, which could be lowering the surface temp of the ceiling, and adding to the condensation problem.

This does make sense. Strangely though, my internet searching among the "experts" has indicated that wherever possible, having the fan installed directly in the shower area is better, so I thought I was doing the right thing by moving it.
 
This does make sense. Strangely though, my internet searching among the "experts" has indicated that wherever possible, having the fan installed directly in the shower area is better, so I thought I was doing the right thing by moving it.

So if this wasn't an issue before moving the fan then apparently in your situation, having the fan shower won't work for you ?
 
Im thinking the fan is not ducted properly. If it doesnt have a path to remove air, its probably just cavitating..
 
Im thinking the fan is not ducted properly. If it doesnt have a path to remove air, its probably just cavitating..

In installed the duct myself. It goes to the roof. I went on the roof today with the fan running and verified lots of air blowing out.
 
Did you raise the floor in the new bathroom like adding tile and making the space below the door to small to allow enough air in?
 
Just to add to this, I think a fan,light over the shower must be run thru a gfi protection.
If this wasn't a problem before, maybe you are moving the fan back where it was.. I would add to the insulation over top first as that is the easy and cheap fix, if it helps.
 
I don’t know for sure but I would suspect the smooth paint is much more likely to show condensation and maybe even form condensation than the popcorn. The ceiling before could have been actually holding some moisture and letting it evaporate over the few hours after your shower. Now with a smother higher gloss finish there is no absorption and it’s just running off.

I also like long steamy showers and had a similar problem at my old house and when I redid the bathroom I located a shower top. So what I had was the enclosure walls and then about a foot of tile then the molded top. I went with glass doors and above the doors was about a 4” opening is all. It was a poor man’s steam shower of sorts. The amazing part was I hardly had to run the fan after that and mirrors no longer steamed up as bad.

I can’t remember now where I got the roof cap at.

Similar to this. http://www.homehardware.ca/en/rec/i...b-Walls/_/N-ntj8jZ1z141kd/Ne-ntc74/R-I3214356

Or this. http://www.altrekproducts.com/bathware-products/ac-32-roof-cap.php
 
Did you close off any vents etc. when you renovated? My first guess would also be the ducting. But since you said you checked the airflow, we have to reach a little further.
If you don't have enough air replacing the heavy air, you might not get enough circulation. Next hot steamy shower, leave the door cracked open a bit or a window if available. I know this isn't the final solution, but it'll give you another clue to solving this ( and your spouse a little smile;)).
You could also go back on the roof to check with the shower running to see if the unit is working well with steamy air.
 

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