Hi Carol, I hope this helps! https://www.youtube.com/watch?v=3l5q0xaQEf8&list=PLZ0v_5OZ_bnNGTvaJ2YFrvw3GoaM5nV2r I was forced to replace all the old windows in my home and made a real point to go with vinyl or steel - hopefully yours can be repaired instead!
Carol: maybe this will help
I think they have to be replaced if they are rotten.
If assume that the wooden frames are what is rotten and in that case they have to be replaced in order to be safe and for energy efficiency.
It depends on how bad it is. If it is just a small area caused by damp you can remove the damaged and do a small repair. https://www.wikihow.com/Repair-Rotted-Wood
If it's just small spots, Minwax makes a wood hardener that may work for you.
Replacement is really the only thing to do with a rotting window. If it's the sill or trim, you could replace it rather than the entire window.
if there is rot, there is mold. And water damage. Mold is so toxic to human health. You need to remove it safely so as not to contaminate your home and cause environmental illness for you and your family.
You need to cut away the material about 24 inches surrounding the mold. And you should just replace the windows an frames all together Consider finding w skilled remediate for a free estimate. Dont skimp on moisture control.
Also make sure the gutters are in goo repair
Yes, rotting windows you want to replace! Water can get in easier and cause a lot of damage to the wall and to the room if there is mold. If it is rotting, then water probably was the main cause. Also, replacing your windows with new may save you in heating and electric bills.
Hi Carol: If you have pictures, that would help. You can replace the wood and use wood putty to fill in any holes that are in the wood. You don't mention whether or not these are exterior or interior problems, like interior windowsills. Once you replace the wood, be sure to put some type of preservative on it like a thin coat of Thompson's Water Seal before painting or staining. Good luck