Condensation on inside of windows

1993 side by side condo units, wooden foundation - thermal pane windows have allot of condensation on the inside of all of the windows, 1 window has condensation (on the home interior side) in the middle of the window. Home owner tells me the neighbor has the same issues with condensation. No humidifier in home.
Looking for possible causes of excessive moisture.

What is the moisture reading in the home .

**Go too **

Are there Drapes or curtains tight to wall /Ceiling /Floor stopping air movement allowing the windows to get too cold.

I like to see the humidity in our area below 50% in the winter .mine is 37% and windows are dry .
I have an auto Dehumidifier that comes on if it goes over 45% this seldom happens

High humidity inside.

no, static in air

low humidity

There has to be, otherwise there wouldn’t be condensation forming. Is it only in the colder months/winter?

Just had one like this the other day, and the ductwork was disconnected in the crawlspace, and there was staining gazebo water - try looking this direction

With no humidifier present, my next suspicion would be a disconnected dryer vent pipe or improperly terminated bathroom exhaust fan.

As everyone said, the humidity is too high. How much is enough? 50% rh is too high for a place with cold outside temperatures, and Iowa can be very cold.

If indoor temp is 70 the dewpoint at 50% rh is about 55 F, which could well be the temperature of a typical double glazed windows if the outside temperature is near or below 0 F. Use this on line calculator to play with different temps and relative humidities. What is ideal will vary for location, I am in Edmonton where daily winter temperatures are close to 0 F, so I tell my clients to keep relative humidity below 30%, ideally near 20%.

Today the outside temperature at my house -9 C or 16F my windows are 14 C or 57 F my inside temp is 70 F and rh is 24, so I won’t see condensation in my house on anything that is above 40 F

If you slow down, I think he is talking about between panes of glass, not on the glass.
(but there is a chance he doesn’t know what he is talking about…)
That’s why he is here.

This is window defect.
Both residences have the same issue because they are the same windows.

Windows installed incorrectly. Possible lack of insulation(spray foam,etc) around windows. Any exterior caulking present?

Perhaps the Condo’s were built with cheap windows which are now drafty. Inferior weather stripping where the two sashes meet, locks that don’t tightly seal where the two sashes meet, gaps where the sashes slide up and down on the master frame, improper shimming at the middle of the window and lack of insulation around the master frame/jamb are all common problems with inferior windows and/or poor installation.

Air infiltration around the window meets warm air and condenses.

Dave, I think he’s talking about condensation on the glass, picture’s would help.

Tim you have been back on the forum many times since you asked this question why have you not given us more information so we can help you .

I might be reading into this, but I take it as two separate window issues.

Does this sound familiar? Same cause and issue.

I would venture to guess that he has no further information to share.

If you have condensation on the inside of your windows you have two potential issues.

#1 the temperature of the window is below the dew point temperature of the indoor air.

#2 the amount of water vapor in the air has risen the dew point temperature to the temperature of the window surface.

Excessive source of water vapor.

Inadequate building ventilation.

I guess we can put this one to sleep.

Anyone else find it odd that it’s a 1993 build with a wooden foundation ?
Off subject but he mentioned it for some reason .

Bet it is an old structure with no exhaust fans .

Good find I should have seen that … Thanks Bob

Long time lurker, first time poster.

Note highlighted area above and David Andersen’s thermal image in the picture below (name is a bit ironic considering the circumstances).

In the mid 90’s few window companies used argon gas inside their IG units.

Simply, window energy performance just wasn’t on the top of too many people’s “want it” lists and few window companies were interested.

Andersen (with an E) was an exception. Andersen was ahead of the game offering windows with argon gas fill.

Unfortunately the IGU seal technology at the time wasn’t up to the task of keeping the argon inside the space between the glass. Even though the seal was closed to air/moisture from the outside coming into the space, it wasn’t good enough to keep the argon from packing up and leaving.

Nature may abhor a vacuum but nature loves balance and that 90% argon inside the space wasn’t in balance with the 1% argon in the air we breathe. Nature wanted that changed.

As the argon exflitrated the IG unit it wasn’t replaced by outside air because the IG seal was intact resulting in a partial vacuum between the lites. This partial vaccum resulted in the inner and outer lites going concave towards the center of the IGU. If the IGU seal fails, you cannot have collapsed glass.

Narrower airspace = less insulating value = colder glass = potential for dropping below the dew point in the center of the window.

Normally the center of glass is the warmest part of any window system, that’s why condensation is generally confined to the outer edges. Not in this case. With center glass collapse, the center of the window became the coldest part of the window and resulted in condensation/moisture/frost in the dead center of the IGU. Windows with collapsed glass will show condensation (potentially) much earlier than windows with "normal IGU’s.

Worst case, the glass has been known to shatter for no apparent reason. It would generally take a glass expert to CSI if collapsed glass was the cause of a window break.

Andersen (with an E) repaired or replaced many thousands of IGU’s that had the collapsed glass issue all the way up thru the end of the 20 year warranty period.

Today, if you see a window with center glass condensation, it is almost 100% certain to be out of warranty since the problem was confined to about a three year period. In fact, 1993 seems a bit early for collapsed glass - really should be more like 95-98. I would be interested in seeing the actual manufacture date on the IGU logo.

At this point I would probably recommend changing the IGU if someone has the collapsed glass issue and the glass is out of warranty. But if that isnt an option, there is a fix. Just google “collapsed glass” and there is at least one you tube video, that I know of, that shows how its done.

Anyway, I know this post is late but since none of the previous posts addressed this issue, I thought that perhaps this might help an inspector sometime.