There is more horizontal force when a person lays in a hammock than their weight. The force is higher when the hang is flatter. A hammock with a 200 pound person in it will apply about 1,200 pounds of horizontal force to the vertical support when there is a 20 degree hang.

Vertical supports in shelters may not be designed to take this much horizontal force. Even though the log looks sturdy, the nails at the bottom may not hold.

I suspect this law originated when someone pulled a big log out of the side of a shelter and the roof fell. It probably resulted in a lawsuit because this is America.

Think about this if you plan to hang a hammock between the supports for your porch. Please make a video if you do.