not visible in the pictures, there are steel cables running in an x-pattern and from side to side at the top of the vertical posts. I've been in the barn in some pretty heavy winds and it doesn't move. by the time it is completely sided, there will be laminated beams and floor joists for the loft tieing things together even better. Fortunately, the usual at my place is just breezy and 'high' winds are rare.