Measure the length of the exposed track when the window is completely shut.
Cut a 2 inch wooden dowel to match your measurement (you may need to take an inch or so off to be able to remove it once it is in place).
Insert the dowel into the exposed end of the track. Make sure it is all the way in and cannot be jarred out by jerking the window open. Having the dowel in place will not allow the window to slide open.
Open the window as far as you can.
Insert several sheet metal screws in 6 to 8 inch intervals along the top of the exposed track.
Adjust them as necessary to allow the window to slide below them without catching. Their presence will keep the window from being "jumped off the track" by a burgler.
Obtain a chain lock (such as the kind used on doors).
Attach one side to the sash of the window and the other to the casement using the longest screws possible for both.
Shorten the chain as much as you are able to while still being able to comfortably lock it.
Things You Will Need
- Wooden dowel
- Long screws
- Chain lock
- Sheet metal screws
- While locking up is extremely important, secondary precautions, such as alarm systems and motion sensor lights are also very helpful in securing your windows.