I live in an old home with single pane windows. My house gets very humid 50-60% range and higher if I don't keep the home very cold. My hunch is that my windows are very leaky and the outdoor summer humidity is leaking into the house with the heat as well.
The reason I think the windows are the primary source of humidity is because the interior window has a LOT of condensation on the outside of the glass. The outside of the interior windows are also covered in mold and I have to clean them regularly.
I'm already planning on installing some stick on plastic insulation for all the panes as suggested in many other posts, but shouldn't my storm windows prevent the outside heat and condensation from reaching my interior window? I've seen on some youtube videos that there should be a gap at the bottom of a storm window to allow any drainage to leak out, but if that's the case then the window provides little insulating benefits?
Actually, now that I've looked outside at them I can see a few are well sealed all the way around, but perhaps it's just that the storm window is very old and its gaskets/seals/etc. have deteriorated.
Should I replace my storm windows? What should I look out for when replacing them? Any good guides to follow?