Take time to lay out the fence carefully. An incorrect measurement could result in compounding problems. Aluminum fencing works fine with gentle dips in the land, but if you're dealing with extreme slopes, you may need to choose another fencing type.
To plan your fence:
When dealing with slopes, you have two options:
If the slope is less than 12 inches over a 6-foot run of fence, the panel can be raked or slanted. This will maintain a uniform space under the fence, which is particularly important if you're trying to keep a dog inside the fence. When raking panels, no special posts are required.
If the slope is greater than 12 inches over a 6-foot run of fence, the fence panels should be stair-stepped to accommodate the landscape. When stair-stepping panels, use end posts instead of line posts. The predrilled holes in the posts will work for one side of the connection, and you can make holes in the appropriate places to receive the rails of the stair-stepped panel.
The most important part of a fence is underground: the posts. Using a post hole digger or power auger, dig the holes in the depth and diameter recommended by the fence manufacturer. Backfill each hole with about 6 inches of gravel to drain water away from the bottom of the post. Remember to dig the hole in a bell shape, with the bottom wider than the top, to stabilize the post.
An aluminum fence is installed by setting the posts and fastening the fence panels between them. The exact instructions for doing this will vary depending on what brand of fence system you buy. Pay close attention to recommended measurements for the distance between posts and for the depth of post holes.