There are two methods of installing fencing going up a slope. There's the parallel method in which the horizontal fence rails run parallel to the ground, and the step method where the rails run level to the ground. Only the step method can be used with prefab fence panels. Installing fence panels on a slope requires proper planning, but can be accomplished by following these instructions.
Pound a stake in the ground where the fence will begin at the bottom of a slope.
Pull the tape measure out to a distance of 8 feet from the stake along the intended fence line. Carry the 2 by 4 by 8 foot board in the other hand. Set the 2 by 4 upright at the 8 foot mark on the tape measure. The 2 by 4 should be at a perfect right angle to the tape measure. Drive a stake in the ground. Repeat this step for each additional fence post.
Dig post holes by hand or rent an automated post hole digger. Dig holes 18 inches deep and three times the diameter of the post. Shovel 4 inches of gravel into the bottom of each hole for drainage.
Mix up quick set concrete in the rubber tub using a garden hoe to mix water in. Place a fence post in a hole checking to make sure the centre of the post is at exactly 8 feet on centre from the previous post. Shovel in concrete mix and check the post for plumb-level by holding a level on one face of the fence post and adjusting it to level. Next place it on an adjoining face of the 4 by 4 post and adjust it to level. The cement should start setting up in one or two minutes.
Repeat Step 4 for each consecutive fence post. Allow cement to cure fully. The minimum cure time is 4 hours after cement hardens.
Set the first prefab fence panel between the first and second fence posts at the bottom of the slope. The lowest bottom edge of the fence panel should be at least 2 inches off the ground. The top of the fence should be at least 2 inches above the top of the fence post. Set a scrap piece of 2 by 4 on the ground next to the second post with the 4 inch face facing up. Set the bottom edge of the fence panel on it. Lay a 4 foot level on the top rail of the fence panel. Have a person at the other end of the panel raise the panel until the rail reads level. Make a mark on each fence post 2 inches below the top of the fence panel.
Lay the fence panel flat on the ground. Stretch a string between the 2 fence posts and hook a line level -- small plastic level -- on to the string. Adjust the string until it is level and mark each post at level.
Lay a metal square at each mark and draw a straight line across the face of each post perpendicular to the vertical edge of the post. Cut the posts off at each pencil line.
Reposition the prefab panel so the lowest end is 2 inches off the ground, level the panel and secure to fence posts with 6 D galvanised nails.
Repeat Steps 6 to 10 for each consecutive prefab section.
With the step installation method the end of the prefab fence panel that is nearest the highest pitch of the slope will be set 2 inches off the ground. The opposite end will be much higher due to the panel being installed level to the ground rather than parallel to it.
Call the utility company to have the ground checked for underground wires before digging any holes.