You feel cold air around the window frame when the window is closed.
The biggest mistake DIYers make is "caulking over" old, cracked caulk. Do not do this. You are essentially sealing a bandage over a wound that is still dirty. Use a utility knife or a caulk removal tool to scrape out the old material. It is messy, tedious work, but it is the only way the new sealant will adhere properly.
Before you grab a caulk gun, you need to play detective. Not every draft requires a full sealant overhaul. You need to distinguish between a failed seal and a failed mechanism.
Not sure if your windows need attention? Watch for these common signs:
Cracked sealant allows water to enter the wall cavity, which can lead to rotten wood, mold growth, and damaged drywall.
While many people can handle basic caulking, fixing double-glazed windows with "foggy" issues can be more complex.