The building rides on a trailer, so you need enough vertical clearance for the structure plus the trailer height to pass under anything in the path: tree branches, power lines, carport overhangs, basketball hoops, you name it. For most buildings, figure at least 14 feet of overhead clearance along the delivery route.
If you've got a tight spot with low branches, trimming them ahead of delivery is a lot cheaper than rescheduling. Walk the path from where the truck would enter your property to where the building goes, look up, and plan accordingly.



