Does it because of fog in the window? I find a new company call http://fogout.ca/home.html. I guess their process should work for most of window. It basiclly drill a hole on your outside window to let water vapour out.It should cost you less than change the window. There is some risk involving drill a hole on a tempered glass. The tempered glass may broke. But It look like ok for them.
Thanks
not only because of fog. Since my home is 17 years old, the wood of windows is not very good and some parts are rotten so I want to change them to PVC.
I may go to homedepot to check
