Hello,

We have oil heating and our windows are always fogged up with a good amount of condensation when the heater is on. We are now starting to see red mold forming on the bottom of the window panes.

The normal winter humidity level in the house is usually around 65%. Is that too high? Is there a way to stop or limit the condensation?

(It's been extremely cold and dry in the last 3 days, and although the heater is on even more, there is no condensation on the windows - humidity is only at 45%).

Thanks,

geektb

What type of windows do you have, double pane, storm windows, etc. A fairly well sealed house with single pane window is going to fog up. Breathing seating, cooking, houseplants, bathing, laundry, etc. add moisture to the house. In coming cold, outside air drives moisture out. Best thing might be to add storm windows and keep more heat in the house. You could also use bath or kitchen vents more to expel moisture. 65% shouldn't be too high. With the inner window not as cold after adding storms, you should get less condensation and mold.

We have single pane windows that are completely not insulated. I was thinking that our next big project would be to either replace the windows or install panes. Do you happen to know which approach is cheaper? These are the original windows and I like the way they look, but can live without the constant breeze.

I don't see prices of stuff, but I am sure adding storm windows is going to be both cheaper and easier than new windows. If you like the looks of your current windows, and they seal fairly tight, and are in good shape, I would keep them and add storms. You may even be able to find them with the newer coated glass that helps hold the heat. The storm windows go on the outside, and will change the appearance of the trim around the windows, but not the inside. I have read that storms do as good of a job or better at retaining heat than double pane windows.

The one advantage of new windows is the opportunity to seal and insulate between the windows and the walls, a detail often skipped in the past.