The moisture levels are too high for the insulation and
environmental conditions. Constantly wet windows and
walls lead to mold and bacteria growth and encourage
Of course the problem can be solved with either or
both. The best is more insulation.
BTW:I replaced sashless windows with aluminum units in
my previous house and they were equal or even nicer in
some ways than my current double glazed all vynyl
units. They were thermally broken and built like two
completely independant window systems fastened
together. More air gap than the best size though.
High humidity *could* be the OP's problem and that would lead to some other
But high humidity alone would *not* lead to *FROST* on the inside of the
window as the OP has. That can only happen if the inside surface of the
window/frame is really cold (<32F). With a really cold frame, even 30% RH
inside will condense/frost on the window (dew point for 70F and 30RH is
Adding storm windows will help to reduce heat loss and stop the inside
frame/glass from getting so cold.
Huh? That makes no sense and isn't true based on
personal experience. A storm window even if it
fits over just the glass, will increase the
temperature of the inside glass. But, storm
window typically fits just inside the outside trim
or fit on top of the trim. Thus decreasing any
air infiltration between the window and the frame.
Storm windows can easily reduce temperature
fluctuations in a house, especially those with
metal framed windows.
On Fri, 02 Dec 2005 01:32:50 GMT, "George E. Cawthon"
I was not talking about storm windows. The OP had asked if the
(improper) installation of the windows could cause the problem. My
reply was ONLY to that question. Look at the number of >> before the
messages. My reply, with >> was to the part with >>>
Pete, the ideal RH for you may be higher than the ideal Relative
Humidity for your windows. It depends on the windows, how cold it is
outside, how warm it is inside, how your house is constructed and the
people who live there. It can't really be answered over the internet.
Most people would prefer 35 to 45% RH. The windows may sweat under
We installed an HRV last winter for that same reason, windows so wet that on
very cold days, ice would form.
We had to chisel the ice off the bottom of the patio door in order to open
it on extreme cold day. (Canada)
The HRV works fine and has helped. BUT!!! the humidity is at 36% now and it
is only -7 Celcius outside which isn't very cold and the windows have
condensation at the bottom again.
I think our windows where either or both : very cheap and poorly installed.
where it says:
The most critical item in preventing moisture damage is to keep indoor
relative humidity at reasonable levels during the heating season.
While exceptionally dry conditions may cause respiratory problems and
shrinking of wood furniture or trim, humidities of 30 to 40 percent
appear to prevent these problems. When indoor humidity exceeds 40
percent during cold weather, moisture problems begin to appear. It is
difficult even with proper vapor retarders to construct a house that
will not have condensation problems when indoor humidity exceeds 40
percent. When a house is retrofitted with insulation without the
benefit of vapor retarders and air leakage control, an even lower
humidity may be required. Persistent condensation on double-glazed
windows is a good indicator that relative humidity is too high and may
cause damage to the exterior finish."
Look on a humidity meter. Ours says indicates
normal from 50 to 75 percent. Humidity in our
house usually runs between 50 and 65 percent. My
wife complains anytime the humidity drops below 50
percent. And no, our windows don't get wet.
Condensation on the glass means that the glass is
cold. To stop condensation increase the
insulation (add more layers of glass) or increase
-25 F, but that's the extreme, low teens to zero
is a fairly common low in December and January.
Winters are highly variable.
We have no problems with mold, no problem with
structural damage. The ambient humidity varies
quiet a bit though out the day and most statistics
for the area (average monthly and daily highs and
lows, etc.) don't provide a real picture. Natural
humidity is pretty low. Weather broadcasts in the
summer will often indicate a humidity level of 50
percent, but that is likely only for an hour or
two with most of the day below 30 percent. This
also an area of low precipitation, annual average
is in the 11 inch range.
When you take a shower, does the bathroom mirror fog up? Does this
mean that there is something wrong with your mirror and you need to buy
a new one?
When the same thing happens to a window for the same reason, why do
people always blame the window?
nope, mirror doesn't fog up. Not too much humidity in the house, then what?
Seems like the answer lies in the glass behing too cold....some other
windows have better insulant between the two panes of glass.
Argon helps- a LITTLE bit - but thermopane basically is thermopane.
Non-conductive spacer bars help with "edge freezing", but if you are
getting wet window panes and ice, your humidity - WHATEVER it is, is
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