Constructing fences on slopes essentially similar to normal fence construction with some adjustments.
The three previous blogs discussed the construction of the six- foot, three railed fence, the hog wire fence, and the horizontal fence. On January 1, 2019 we wrote a blog about the construction of redwood retaining walls. All four of these blogs assumed the construction was to take place on level ground. Now we will discuss how we alter the construction to build fences on slopes and uneven job sites. Let us first say that with slopes, we would NEVER build a slanted wall. That would look very amateurish. Instead, we prefer the look of what we call a ‘stepped down’ fence.
On level ground we begin by laying a taut string line at ground level or 1” above grade. This starting point does not change on uneven ground, since this string serves only to align the posts, not to determine their height.
To build fences on a slopes, we space our posts the same as on level ground (eight feet apart for the six foot fence, four feet apart for the horizontal fence, etc.). We dig our post- holes 9” diameter to the appropriate depth, according to the height of post (six foot fence – 24” deep, three foot fence 16-18” deep).
The difference is the height of the downhill post. In order to build a level fence, the downhill post of each fence section must be longer than the uphill post. If the uphill post is six feet tall (plus 24” depth of post-hole plus 1” clearance above grade), that’s a total of eight feet, 1” or 97 inches. If the ground eight feet away from this uphill post is twelve inches lower than the uphill post, this downhill post must be twelve inches longer.
When the two posts are set in concrete such that the top of the two posts are level, this fence section may be constructed with rails and fence boards or with rails and hog wire. Upon completion of this fence section, this will leave a small open space triangle at the bottom of the fence, twelve inches from the ground on the downhill side up to the bottom of the bottom rail. This space gets smaller and smaller and disappears as the ground gets closer to the uphill post. This space may be filled later by installing a ‘kicker’ which may be a 1×12 redwood board specially cut to cover this space and screwed to each post.
This process repeats at the next section and continues to the end of the fence. Note that the slope may or may not be uniform along the length of the fence. The little triangle below the bottom rail will therefore vary in size.
The last adjustment is with the 2×6 cap on top. On level ground we were able to span several posts with the 2×6 cap…on sloped ground with the ‘stepped down’ fence, we are only able to span posts that are level on top. This may mean only short caps spanning two posts.