While the most thorough and sure way to eliminate the problem is by getting a structural engineer in to look at the garage take measurements and fix the sag.
Garage door sagging in the middle.
There are several factors that may cause a garage door to bow in the center.
In some cases basic exposure to the elements along with temperature fluctuations may result in bowing.
There are things you can do yourself to fix the problem although they may not be as permanent as having a professional fix it.
In other cases the weight of the garage door in conjunction with an automatic garage door that is attached to the center of the door may be the cause of bowing.
It could be the case that a strut needs to be installed in order to keep it working as it should.
You can do this.
Garage door sagging in middle fixing misaligned tracks.
A sagging garage header is essentially a structural engineering problem.
Getting your garage door in tight lean condition requires a bit if elbow grease and a good set of hand tools.
A wooden garage door may sag in the middle if it is bumped with a car or other large object in the garage but there are less obvious reasons that can cause such a door to sag.
If the tracks have become misaligned then it s not too difficult to fix them.