Condensation around windows

Attached are some pictures of exactly how much condensation you can see around the window. Visible is also possible microbial growth. It is a double hung double glazed window and condensation is not between the glazing. What can be causing this issue? High humidity levels in the home? Insulation problems? Bad seal? Flashing? I’m only asking about possible causes because it’s at my own place so I would like to fix it. Any help is appreciated.

Hi moisture levels in the home can certainly contribute to that. Where are You , what is the weather like ?

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I’m in Florida and usually very hot and humid, but the past couple days we’ve been in the high 30s and 40s.

This is a normal occurrence with metal frame windows. The windows have a high “U factor” which means they transfer energy very well (which is not a good thing per se).

When it’s cold outside the metal frame gets cold, and presumably it’s warmer inside, so when the warm air comes into contact with the colder glass and frame it results in a release of moisture.

Similar to a glass of ice water sweating on a hot summer day.

Good luck!


Do you have curtains n the windows, Is this a bathroom, what is your humidifier setting, to you have exhaust fans in the bathrooms (with timers) do you have a lot of plants, do you have an aquarium? Have you taken the interNACHI course on condensation in your home?

Thank you @ptolbert that makes perfect sense. Like I said before it’s usually pretty warm in my area but temperature has dropped a lot more than usual the past couple of days.
@jolson81 its a bedroom window, there is a bathroom in the bedroom but it does have an exhaust fan, no plants, no aquarium, I have not taken that course but will look it up, thank you :+1:t3:

That will do it, especially with metal framed window as Patrick notes below.

How many marijuana plants have you got growing, just kidding.


My guess is you had the heat on overnight & found it in the morning.

We have double glazed vinyl windows and we have to keep our blinds up a little and down a little to create an air flow. Otherwise we get some condensation on the bottoms of our glass.

What is your ‘source’ of heat?

LP? Kerosene? Wood products?

Mine is NG…

Couple of links that may help you.


Propane has some water in it and that’t what the use in FL often.

I had to leave a couple windows cracked to let moisture out with an open propane fireplace I had in one house.

If that was for me, it’s a heat pump. And we haven’t had the heat on.
And thank you @mcyr excellent read that does help.

You are the OP that asked the question, are you not?
(Not my fault this POS MB likes to override and hide quotes)!!

It appears that there is some possible mold growth. I guess your relative humidity is above 60%. How old are the windows? I’d look for moisture penetration from the exterior. Keep it as dry as possible and wipe it down with a mixture of Borax and a neutral cleaner.
Dick Mullen, Mold Inspector, Boston, Former Fla Resident

Welcome back to our forum, Richard!..Enjoy! :smile:

We appreciate when knowledgable members share…thank you.

Tiles on the inner window sill suggests it is.
Likely high relative humidity in the bathroom.
Turn on the fan and return in 20 minutes.

I have noted that the east window in a house will get this type of moisture from cold nights and the early sun. Cool windows, warm sun may cause moisture.