interior wall and window moisture in winter

Pam, I think this is very common -I've certainly had this problem and know many others who have as well. Wasn't this a sales feature?

"Drink healthy distilled water off you very own windows!"

I too would be interested to see if there are any good solutions out there. -L

we use a delonghi dehumidifier in our bedroom and it seems to help get rid of some excess moisture that can build up on windows, skylights, and from long, hot showers - certainly not a "cure" but helps a little (definitely a good idea if anyone's allergic to mold) - i imagine there are some more robust dehumidification solutions out there - but things hold about 40 pints of water and we can empty that at least once a week in winter (also has an option to pump right out of house, but we haven't installed that)

http://www.amazon.com/gp/search/ref=pd_sl_aw_tops-1_kitchen_5695991_1/10...

Your description is out of a text book on the topic of vapor capacity vs temp.

The higher the air temp, the greater capacity to hold and the higher the due point.

Says your house has a noticable temperature gradient from the floor to ceiling.
The "line" where there is no moisture on the window to where
there is moisture is where the due point temp is reached. Above it's
higher so the vapor continues to be held in suspension. Below the temp
is below, so precipitates out of suspension to form water.

Why the fan helps, it stirs up the air and therefor reduces the temp gradient.

This one reason why I don't like embedded heating in my Eichlers. There
just isn't enough air flow, so the hot air stays at the ceiling. Water based
heating systems that use radiators do a better job of moving air than
infloor systems. Concentrated heat with a fin system to accelerate the
air and heat transfer, which creates a large temp differential, so it will
raise fast and cause an updraft at a "point", which will draw in cold air
from the surrounding floor area.

No holes needed (though there are leaks in any house) to cool the air, as
the large windows do not insulate well, unless they are double/triple paned.

Most dehumidifiers also have a fan, so they do both. Remove moisture
(via an air conditioner system) and move the air to reduce any temp
gradient in the room's air volume.

Solutions are to use a fan, dehumidifier, insulate the rooms better and
consider a different heating system that has more air flow.

You will need to keep the humidity in your home between 30-50% to prevent condensation on the walls and windows. I did this by installing a ventilation system in my roof just below the foam roof. There was an article that my husband and I wrote for the Eichler Network flyer a few years ago that details our experience. In short we run our ventilation system all the time and it keeps our indoor air quality good in the winter and keeps the house cool in the summer (the house is ventilated but we close the doors during the hot part of the day to keep in the cold air). We really love it and we have absolutely no condensation or mold to speak of.

Here is a little bit that was written on condensation:

http://www.eichlernetwork.com/HDint_remod3.html

More chatterbox discussion is here if you search on "ventilation":

http://www.eichlernetwork.com/chatterbox_lounge/viewtopic.php?t=359&high...

The system we installed is detailed here:

http://www.lifebreath.com/life.htm

Short of this, you should run your bathroom fan and kitchen fan as much as possible during heavy use times of cooking and bathing.

Let me know if you want a soft copy of the article.

LynnDrake2004ATyahooDOTcom

It sounds like you have way too much moisture in your Eichler. The best solution is adding fans in the bathrooms. These can be easily retro-fitted without even involving us.

Click Resources on our Website, top-right home page. Then find bathroom fans in the left column. There is also a link to Electrical conduit retro-fit. You will find printable instruction sheets with excellent detail drawings. The arcitectural drawings are highly detailed and have enough information for your contractor to do an easy, inexpensive fan installation. Please make sure there is every intention to follow our directions...especially with minimum heights and clearances.

Symantics and out of context on a few things.

Relative humidity is out of context UNLESS in reference to temperature
of both the air itself and the surfaces it touches.

With no differential between air temp and solid surface temp *AND*
humidity in the 90% range, there will be ******_NO_******
condensation on the solid surface.

Then with a relative humidity of 30% and a high temperature differential
with the solid surface colder than the air, it will condense onto the solid
surface.

You can solve it many ways. Remove the moisture from the air, stir the air
to remove temperature gradiant, increase the air temp, increase the solid
surface temp, insulate the solid surface from the cold so that it's warmer,
use a de-humidifier, or any combo of the above and then some.

The dew point varies dependent on the differential temperatures of the
air and solid surface (actually don't need a wall of glass, just a partical of
dust will do) and the humidity percentage. Meaning the temperature tha
moisture will precipitates out of the air varies.

To remove it from the air, run exhaust fans or dehumidifiers inside the
room (which does the same thing as the windows, but on the AC fins
and drips into a catch pan, which needs to be emptied).

To change the temp gradiant, insulate the windows (double pane), which
is very expensive. Or stir the air to keep the air both warmer and more
consistant in temp from ceiling to floor. Fans or fans in the heating system.

Or heat the air so that it will hold more moisture.

Each or combo of methods has a price tag both in $$$$ & time/effort.

In the meantime, some ways to prevent wall condensation (and mold growth) for minimal $$ is to do the following:

1) Replace your bathroom fan switch with a 60 min timer. Run the fan for 60 minutes after a bath or shower.

2) Run your kitchen fan when cooking or leave it on during heavy use (i.e. in the evening when everyone is home).

3) Get a meter to measure your humidity in the house. It's easy to run the relative humidity (at 70 deg F) past 60%. I have this one:

http://www.omega.com/ppt/pptsc.asp?ref=PTH-1XA&Nav=temhu03

60%-70% relative humidity coupled with outdoor temperature in the 30's with old Eichler insulation create conditions for wall condensation.

When it gets too high, you can run the fans.

4) Remove closet doors on closets that are on an outside wall.

5) Move furniture and other objects away from an outside wall- especially corners.