Hello,

I have a hallway bathroom with the back wall to the outside of the house, in Wheaton, IL. Now that it's really cold, we are seeing water condensing on that wall to the point where it flows. Also, that bathroom is significantly colder than any other room in the house. We just moved in, so I do not know if it is also the hottest room in the summer, but I suspect it would be.

Some details I do know:

* the house is built on cinder blocks, effectivly creating a 2' crawl space under the house.
* the attic insulation is R30 throughout
* there is no insulation in the outside wall ( my brother-in-law installed the bathroom window and noticed it missing)

Any suggestions as to what is going on and how to fix it? I think the water's condensing because of the differences in temperatures due to no wall insulation and was thinking to add blown insulation by making small holes in the wall... not sure if foam would be the way to go.

Thank you for your guidance.

Regards,

Chris

The temperature in which water condenses on a surface can be determined from a dew point table such as this one:
Dew point calculation chart & info.

You need the Relative Humidity of the air, the temperature of the air and temperature of the surface.

So, to prevent condensation, you either need to raise the temperature of the surface or lower the humidity.

Insulation will raise the temperature of the surface.
Ventilation will generally lower the humidity.

Stupid solutions like IR heat lamps would also raise the temperature of the surface.

The first thing you need to do is seal any air leaks into the bathroom. They can be around the toilet sink and drains, around the windows and around the electrical outlet.

If there is a ventillation fan, be sure there is a properly installed check valve in the exhaust.

If there isn't an exhaust fan, install one.

I prefer IR lamps + a fan where the fan is connected to a delay on break timer so it wuns for 15 minutes.

1 switch for light
1 switch for fan with a delay on break, mounted in a single gang outlet box

1 mechanical timer for 3 min for the heat lamp.

Artworkshop1972 - Let me give you a good example of what is going on .IN the summer time when you have a glass of ice tea, its nice and cold , the tempture is say 85 degrees. The hot air hitting the cold glass on the out side of the glass,recondenses the hot air into moisture ( WATER ,running down the outside of the glass) the same thing is happing in your bathroom, cold air from outside the house hitting the hot air inside the house is causeing the hot air to recondense into moisture (WATER), I would bet that your brotherinlaw is right , there is NO wall insulationor some large openings, IS this a NORTH faceing wall, north winds makes it worse.::: TO help solve this problem,#1- make sure all openings in the foundation walls are closed good, have a insulation contractor come out and blow insulation down inside of walls, its not really hard unless you have brick walls on outside . I hope I have helped you somewhat, if I have Rate my answer below. Good luck & GOD BLESS ::::: F.B.E.

Het Art, we thought you just needed interior wall insulation earlier but this doesn't look too good. I will talk to you in a PM re: Wheaton later but you really need insulation in that wall, bet it's the west wall. Remember Wall Fill in Wheaton? They would drill a 2" hole at the top and bottom of each wall cavity and blow in insulation. You can do that too on your own by renting a blower. Since there is no insulation I am betting that there is also no vapor barrier and that's tougher to cure. ACE on Main St. sells a paintable vapor barrier sometimes used on ceiling with no barrier, you could try that. Me I'd just pull down the drywall and do the whole wall over properly, but that's just me.
See you neighbor,
Bob

Thank you folks!

We started with turning on the bathroom exhaust fan, and that significantly reduced the condensation. We then installed a floor heater, and that completely eliminated the problem.

When it is a tad warmer, we are going to take down the exterior wall and redo everything, including insulation and a moisture barrier... it appears, based on how cold the kitchen cabinets are along that same outside wall, that someone took down the whole wall from the bath to the kitchen and forgot to put insulation and moisture barrier.

That wall faces west (I think someone asked).

Thank you for the guidance, and I'll post again when we get the permanent fixes in place.

Regards,

Chris

Art, houses in your area did not always get insulation or vapor barriers back in the 50s. My old house on Ashton Ct had not one stict of insulation in the walls when I bought it. Compensate with R36 or higher in the attic.

Bob,

Ashton Court... Aurora? We just moved from Ashton Court, Aurora... that would be a very strange coincidence... :-)

Chris

Quote:

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Originally Posted by artworkshop1972

Hello,

I have a hallway bathroom with the back wall to the outside of the house, in Wheaton, IL. Now that it's really cold, we are seeing water condensing on that wall to the point where it flows. Also, that bathroom is significantly colder than any other room in the house. We just moved in, so I do not know if it is also the hottest room in the summer, but I suspect it would be.

Some details I do know:

* the house is built on cinder blocks, effectivly creating a 2' crawl space under the house.
* the attic insulation is R30 throughout
* there is no insulation in the outside wall ( my brother-in-law installed the bathroom window and noticed it missing)

Any suggestions as to what is going on and how to fix it? I think the water's condensing because of the differences in temperatures due to no wall insulation and was thinking to add blown insulation by making small holes in the wall ... not sure if foam would be the way to go.

Thank you for your guidance.

Regards,

Chris

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1st you need insulation to be put in the wall. I would open up the wall completely, insulate it and re-sheetrock it. If you are still having an issue after you've done this, then put an exhaust fan in. If still having a problem, then add heat lamps.

Exhaust fan will help and id wonder if your walls are insulated