Mine is 11' 6.75" wide. As long as you can back it in, and get the door open to get inside, you are good to go. I can not open the slide on mine because I have a pole barn over it.
I started with a 12' gate, and ordered a 12' wide pole barn. When the pole barn was assembled it was 11' 11.5" wide outside to outside of the legs. It may actually be 12' if you measure the reinforcing ribs on the aluminum cover. When you subtract the width of the 2.375" wide poles, that leaves 11' 6.75" of space inside to inside.
I made it tall enough that I can get up on top to work on the roof, as long as I stay hunched over.
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