18 ft wide awning extends out 10 feet 2 inches from your house. The 10 and 11 ft wide awnings extend out 9 ft. I always tell customers they really don't have to cover there whole deck. If your deck is a total of 18ft wide figure out where you sit, most of the time you really only need a 12 ft wide awning. Most customers have 1 table and a few chairs that don't take up the whole deck. Also if you have a grill on your deck take that into consideration.

Bill