Glass is an extremely slow-moving liquid. If you live in an old home with old windows, your glass may have started to head south, literally. Loose window panes rattle in the wind because the glass on the bottom of the pane is thicker than the glass at the top. That "rattle room" can let cold air in and hot air out. This will decrease your home's energy-efficiency. Luckily, this can be dealt with inexpensively and easily.
Loose window repair: How it's done.
What You Need:
You'll need a putty knife and some caulk. I recommend low or no VOC caulking. If you can't find it in your local hardware store, order it online. You will also need vinegar and a rag.
What You Do:
1. Apply a small amount of caulk to the edge of the suspect window. Use the putty knife to maneuver the caulk into the space between the window and the frame. Make sure to drive the caulking into the space as far as it can go. The space between the window frame and the glass needs to be completely sealed.
2. Pour the vinegar on a rag. Use the rag to wipe up any excess caulk visible on the glass. If the rag and vinegar doesn't work, use the putty knife to scrape away the caulk.
3. Wait until the caulking dries. Check the window. If you can still see spaces between the window and the frame. Apply more caulk in the places that need it.