Sliding door locks

I need a lock at the top of our sliding door that leads to the deck. They are able to unlock the door now and open it. There are times when I have to run downstairs for the laundry and i'm scared they will open the door and take off.

Does anyone have any locks they are using on sliding doors that are high up that the kids can't reach or open that you are happy with? If you did where did you buy it?

Thanks
Brenda

 

We have a sliding glass, but thank goodness the girls haven't figured out how to open it. I'm interested to see the replies in case this happens to us.

 

I wondering this as well.
I know my parents have a metal bar on their sliding doors, in the middle of the door. But i think that was installed when they got the doors.

 

We installed a silver pin that goes through a drilled hole in the top of our sliding doors. Right in the middle. It's also screwed into the slider by a screw attached to a chain so it will not get lost when we (the adults) remove it. You can get it at Home Depot or Lowes.

 

would this work? Or is that what you're saying they've figured out how to undo?