Help! Ice forming on inside of our windows...

[gbbi_977]

Hello,

We live in a vintage condo apartment, third floor with neighboring units on either side, that was gut rehabbed about ten years ago. We are not sure if they replaced the windows or not at that time, but we suspect they probably did.

This is our third winter in this unit and we've often noticed a lot of condensation on the inside of our windows at winter time. We live in Chicago and it's 8F outside today.

This winter we've kept our thermostat at about 65 during the day/60 at night, and we often use a gas fireplace in the living room (with doors to two bedrooms/bathroom closed) for cosiness and some extra warmth here and there.

We just had an AirBnB guest staying in our spare bedroom, and when I went to strip the bed and raised the blinds, I noticed that the condensation is way worse in there than it's ever been, to the point where it has started to pool on the sills and freeze up again.

We don't know what to do about this or what causes it. Are we keeping our house too cold? Is it just crappy windows? If the only real fix is new windows, how do we minimize the problem in the meantime?

Pictures to follow.

[Ebrat]

I noticed this same thing on some of our windows the other day, so I'm curious to hear people's thoughts.

[gbbi_977]

So a quick google yields the following advice:

- unvented fossil fuel burning devices (which presumably our gas fireplace is) bring extra moisture into the house

- need to leave doors open (guest had them closed all weekend) so air/humidity can ventilate around house

We just turned thermostat up to 70, but I hate having the house so hot...any other advice? Thanks in advance.

[Ebrat]

Hmm...I only noticed it in the morning on our bedroom windows, and we keep the bedroom door closed at night.  So that second explanation makes sense.  You have a flue or something to vent the fumes from the gas fireplace, right?  I thought those needed to be vented outside (I think ours used to be a wood-burning fireplace, so we open the flue in the chimney when we use it).

[gbbi_977]

I don't think our fireplace has a flue/vent at all. In fact I'm fairly sure it doesn't...

[ender]

Could you run a dehumidifier?

Seems that might help with this problem (though perhaps make your skin super dry and electric bill go through the roof).

[MDM]

I don't think our fireplace has a flue/vent at all. In fact I'm fairly sure it doesn't...

Some unvented gas burning is ok - otherwise gas ranges and stoves would kill all their owners.

But a large amount of unvented gas burning can produce a lot of water vapor, an equivalent amount of CO2 and - if the combustion is incomplete - carbon monoxide.

Again, you haven't died yet so it's probably not a significant problem, but have you checked CO (carbon monoxide) levels when you run the unvented gas fireplace?

[With This Herring]

You should get a CO alarm.  They sell ones that plug into the wall.  Better safe than sorry!

Is the air outside drier?  Could you turn off the heat, quickly vent the apartment (fans in windows), then close everything back up and turn on the heat again?

[music lover]

A quick fix is one of those plastic window kits. Also, running a fan will circulate air and help reduce condensation.

[gbbi_977]

OK it got worse - we just looked into our "nook", a small 5' x 8' bonus space above the condo stairwell (gets colder than rest of condo). It has typically had the same issue with condensation forming on windowsill - but today we've noticed that there is black mould all along the inside bottoms of the window frames, presumably because of prolonged exposure to moisture.

So in addition to figuring out how to dry this place out and fix the windows, what do we do about the mold?

[Fishindude]

Combination of things. 
I'm guessing you building is poorly insulated, and has cheap windows.  An un-vented gas fireplace puts out tons of moisture.  This is not good, I wouldn't run in much.   Your HVAC system is probably not circulating air very well either.

We had a very similar situation in our upstairs and it required re-insulation and a new HVAC system in that space to cure the problem.

[FIRE me]

OK it got worse - we just looked into our "nook", a small 5' x 8' bonus space above the condo stairwell (gets colder than rest of condo). It has typically had the same issue with condensation forming on windowsill - but today we've noticed that there is black mould all along the inside bottoms of the window frames, presumably because of prolonged exposure to moisture.

So in addition to figuring out how to dry this place out and fix the windows, what do we do about the mold?

When it's not frozen, wipe it down with bleach.

[letired]

Turn up the heat and do the plastic ASAP. Get some fans circulating the air as well. If you are growing mold, you need to get that shit under control!

Long term, make sure the windows are well-sealed, and look into either replacing the windows or getting storm windows. Since you are on the 3rd floor, interior storm windows might be a good choice.

I'm not sure how the overall insulation of the space plays into this, but also something to look into, especially with rooms that get extra cold.

re mold: YMMV, but alcohol or hydrogen peroxide might also be good choices for disinfecting (DO NOT MIX WITH BLEACH), but I'd do a little research first, depending on what material the mold is growing on. And either way, it doesn't matter until you've stopped the condensation in the first place.

[former player]

Moisture in the air condenses when that air hits a cold surface, so there are two reasons you are getting this problem.  The first is that there is too much moisture in the air in your apartment and the second is that the glass in the windows is cold enough for it to condense against them.

The moisture in the air comes from the occupants breathing, from cooking and from washing.  If you have a cooker hood in the kitchen which vents to the outside, use it every time you cook.  Use the ventilation in your bathroom every time you run water.  Any room that someone has slept in overnight needs to be aired out in the morning, probably by opening the top window for a short while (Yes, you will lose some heat.  No, it can't be helped.  If it's a bedroom which is going to be empty all day it will have plenty of time to become warm enough to sleep in the next night.).  The lower the humidity outside the more effective opening the windows will be at getting rid of the excess humidity inside.
 
Any window that has condensation pooling on it is probably a sign that it hasn't been opened enough.

Bleach for the mold.

[BudgetSlasher]

We have occasionally dealt with a similar issue.

The simple story is warm air can hold more moisture than cold air and the air near windows is usually colder. When there is too much moisture in the air it will condense (in this case on your window).

Your humidity could be too high as discussed above people in a closed off room with no circulation can create raised the level too high (we added a return duct to a bedroom to address a similar problem).

As discussed above things that generate excessive moisture should be vented outside (showers, steamy cooking, ect).

Leaving the blinds down for extended periods has been a problem for us. Pulling them down at night before bed and raising them in the morning seems to be perfectly fine, but leaving them down for days seems to contribute to the issue. When you consider that many people install blinds/curtains as a means of added insulation, it means there is a pocket of air behind the blind that is cooled by the window and air that was not condensing in the rest of the house suddenly has the opportunity to.

[Jakejake]

Until you can get a more permanent fix, make some window snakes (stuffed fabric tube to insulate bottom of window and absorb moisture). Throw them into the wash when you do laundry. You may even find it solves the problem without other more pricey solutions.

[Lulee]

You might want to check that any vents like on your dryer and in your bathroom are routed properly to the outside and that they are working properly.  One apartment I was in had a fan that vented somewhere inside the building which might have been OK when it was put in but was useless at it's real purpose (the fan never worked anyway so I just cracked the window in all but the most extreme weather).  One Holmes on Homes episodes showed a dryer vent that wasn't working as the tubing had come apart on it's long journey to the outside ----allowing dangerous accumulation of flammable lint as well as mold growing into the moisture.  You could be using them appropriately but they might not be functioning well enough to help.

Do your neighbor's beside and below you have similar problems?  Perhaps they've hit on a solution that will help you too.

[Dollarsandcents]

We had this problem last winter (the first year in our current home) and after getting our furnace serviced and the filter replaced the problem has completely disappeared. The filter was in really bad shape.