The 13x13 is actually 11’11”x11’11”. As others said, the instructions are vague. After slipping the corners of the smaller top canopy onto the movable pegs, don’t try to close the pegs against the arms. 

The screens would be better if they closed with magnets instead of zippers, so I superglued magnets along the seam of the entrance we will use most often it’s not perfect but it’s much easier on back-pain than having to bend all the way to the floor with a zipper each time we open and close the entrance. Other than that, this seems to be a great patio gazebo.