Window condensation

Manchester, NH

I have been noticing condensation on my bedroom windows in the mornings. As it is getting cold out at night, we have had the window shut, during the summer the window was open and there was no condensation. During the day we leave the door open, and things dry out, at night we shut the door to keep the cat out.
Is there any way to stop the condensation before we start getting mold growth?

Dublin, CA(Zone 9a)

It sounds like the condensation is on the inside of the window? Condensation is a natural thing that happens when you have cold glass and humid air, so the real question would be why is the air in your room so humid. If you're running a humidifier that would explain it, but other than that, especially during the winter time when you're running the furnace the air inside the house would tend to be really dry so I can't think of where you would be getting enough moisture in the air to cause condensation. Unless maybe your humidity outside is really high and you're leaving the windows open all day, then just closing them at night?

Or do you have dual pane windows and the condensation is in between the panes? If that's the case, it means the seal is broken and you should have a window company come out and either reseal it or replace the window.

Manchester, NH

Yes the condensation is on the inside of the windows. We do not have a humidifier running in the house at all, and the windows are shut all day (we are in New Hampshire and it is starting to get cold.) We have forced hot water heat, so there is no air flow from the furnace.

Spokane, WA

You can install an "insider" storm window. 3M makes a product similar to shrink wrap. You mount 2 sided tape on the frame around the window, stretch the film over the window attached to the tape and then use a blow dryer to shrink the film tight. I used it on a basement window for many years and it works great.
You can find the kit at most major hardware stores like Home Depot, Lowe's or Ace.
Also, you can put dehumidifier kits in the rooms also. They have moisture collecting crystals in a container. Owners of RV's will put them in them when they are put in storage. Make sure that they are o.k. to use in a current living space (ie., fumes etc).

Good Luck!

This message was edited Nov 4, 2006 4:11 PM

Dublin, CA(Zone 9a)

I don't know anything about the window film, but I agree about trying a dehumidifier. I don't know why the air in your house is so humid, but that's undoubtedly why you're seeing the condensation. And with that high level of humidity, mold could definitely be growing so I would definitely do something to get the humidity levels down.

Manchester, NH

It is only happening in the one room. The only dehumidifiers I have seen are larger models for basements or whole houses. Are they made in smaller single room sizes?

Spokane, WA

Go to:

They have a list of retailers where you can buy them.

Brockton, MA(Zone 6a)

Steve, I've been lurking here all along. I'm assuming there is no way to keep the door open a little bit for ventilation without letting the cat in. Rather than trying to get a de-humidifier, you might consider installing a vent in the door. All hardware stores have heater vent covers for about $6 that you can use on either side of a hole you can cut in the door. The cat stays out and the room breathes. No pans of water to empty or electricity needed.
PS, I was born and raised on the west side of Manchester.
Andy P

Apple Valley, MN(Zone 4a)

Just found this post - here's another thought. Set up a small fan to keep air circulating past the window glass. If you have drapes or other window coverings drawn at night, you are trapping air against the window. If you can keep air moving past the glass, you will reduce the condensation problem. We keep our ceiling fans running all winter with the direction of the blades reversed from the summer to the winter setting, and that is a huge help because it pushes the warmer air from the ceiling down past the windows. Since your problem is just one window, a small fan set behind the window treatments should be a big help and easy to try without a significant expense. It won't sure the reason why that window is having condensation, but it might just keep the moisture off the glass until you can figure out the cause of the problem.

If you only have condensation problems on the windows in one room, it suggests that you may have water intrusion from the outside around that window that is keeping the framework damp. Using one of the window film kits will tell you very quickly whether the condensation is due to moisture in the house air or from the structure of your house. If you put the film on and the condensation stops, the problem was simply moisture in the air and lack of air circulation. A fan and/or a door vent should be all you need. If you put the window film on and the window still shows condensation, you have a much bigger problem.

This past summer I began a project to renew the varnish on several aluminum clad wood windows. I discovered that I had a major water intrusion problem that had been going on since I replaced the old hail-battered aluminum siding with vinyl siding in 2003. The siding installers failed to install proper window flashing, and water was seeping into the walls around the window casings.

The good news is that we found the problem before the walls rotted out. The bad news is that I had to replace several sashes and quite a bit of the trim, and even though the siding company stood behind their warranty, it was a lot of work and disruption to have the folks here to fix the problem.

We also discovered that over the years (the windows are 18 years old) the caulk at the seams of the aluminum cladding had worked loose and was allowing water to seep behind the aluminum cladding. "Maintenance free" windows really are not - they do need to be checked on an annual basis to make sure they haven't developed a caulk problem.

So, check the window itself - is it still sound? Are there any visible signs of dampness such as varnish becoming discolored or peeling? Is the wall around the window discolored in any way like a dark shadow? Put on one of those window film kits - they are not expensive and will help you identify the source of your problem.

Manchester, NH

Thanks all for your input. We will look at running the ceiling fan at night to see if that helps, the windows have mini blinds on them for privacy, but should still allow some air flow. If that doesn't work out, we will look at venting the door. Thanks again for all your suggestions.

Post a Reply to this Thread

Please or sign up to post.