Is your awning a manual or electric awning.
Posting a picture of your awning and the sag you are seeing would help us give you a better answer.
IF your awning is not defective, than a simple solution is a center support bar such as this:
http://www.campingworld.com/shopping/item/rafter-vi-by-carefree-white/48788
Note: I've only used a center support with a manual awning and don't know about their use with an electric awning. The electric awning (19', I think) on our new Winnebago has plenty of clearance over the door when fully extended. If your awning is electric, than it either needs adjusting (see the owners manual) or there is something wrong.
Good luck!
2012 Newmar Bay Star 3302
Blue Ox Avail
BrakeBuddy Advantage
2015 Malibu
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