In the picture you show you could place one piece vertically on the wall side of the door on the end the picture was taken.
How to fix a gap in a sliding glass door.
This will retract the rollers and make the door flush with the track.
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Simonton windows doors 102 622 views.
Push in the weatherstripping until secure.
This video shows you how to take apart sliding glass doors.
Remove the door from the track.
Then remove the door stop at the top of the frame which should be as simple as unscrewing it.
Gap between sliding doors doors cannot close properly.
For the best seal my recommendation would be some pieces of weatherstripping or gasket.
First locate the roller adjustment screws and use a screwdriver to turn the screws counterclockwise.
It looks like the gap is caused by the hardware for this barn style door which is a common scenario.
The door opening in the framing is not square.
Sliding glass door adjustments.
You may like my other videos.
Pry out the old weatherstripping from inside the door frame using a flat head screwdriver.
Buy new foam filled vinyl tube weatherstripping the press it.