A fence on a sloped property provides necessary privacy but poses some construction challenges. Fences built on slopes often have gaps at the bottom, not providing proper security for pets and children.
Luckily, with careful planning and the right techniques, you can build an attractive fence on uneven terrain that contains your pets, delineates your property lines, and provides security.
Plan the Fence Layout
There are many fence options to consider when building a fence on a slope. First, walk the property line and use stakes to mark the proposed location. Consider how the fence will connect to existing structures like your house, garage, or outbuildings. You’ll also want to stake out gate locations.
For the most pleasing look, the top of the fence should follow the contour of your land rather than being a straight line across. This method ensures the fence isn’t leaving any gaps.
I recommend checking local zoning codes and homeowner association rules for fence height, location, or materials requirements because many municipalities regulate front yard fences.
Tools You’ll Need
Tape measure
String line
Line level
Stakes
Marking paint
Use the string line and stretch it between the stakes to map out the fence’s path. Then, measure downhill from the string line periodically to determine the grade.
The stakes mark the precise spots for each fence post hole to be dug. Paint or flag the stake locations to make them readily visible.
Dig Post Holes
Digging holes for fence posts in sloped yards takes extra effort, but ensuring your fence rests on a slope effortlessly is necessary. You’ll use a clamshell-style post-hole digger to excavate each hole.
When digging post holes, be extra careful around buried utility lines. Call 811 before you dig to have underground pipes, wires, and cables located and marked.
Tools You’ll Need
This step requires a post-hole digger, shovel, and wheelbarrow.
Holes for your fence posts need to be 2 to 3 feet deep and at least twice the post’s width.
Because the fence height needs to remain consistent across the slope, the posts on the downhill slope must extend farther out of the ground. If using pre-assembled fence panels, purchase longer posts than the minimum recommended length to accommodate the slope.
The uphill post holes can be shallower since less of the post needs to extend aboveground. Allow 6 to 12 inches of extra depth for setting the posts in gravel so they don’t shift.
Proper drainage is important in post holes, so don’t compact the soil too densely when backfilling. Leave room for moisture to drain away from posts.
Set the Posts
Tools You’ll Need
Fence posts
Post level
Shovel
Tamper
Gravel
Concrete (optional)
After digging all the holes, it is time to set and align the posts precisely. Using a level is crucial to ensure posts are plumb and perfectly vertical.
Place 6 to 12 inches of gravel in the bottom of each hole. Position the post and hold it plumb while backfilling around it with more gravel. Tamp the gravel around the post with a hand tamper or the handle of the shovel to stabilize it.
For permanent stability, we recommend using concrete instead of gravel to backfill around the bottom portion of the posts. Mix it wet so it flows easily around the posts and into the holes. If needed, brace temporarily with cross pieces between posts until the fence panels or horizontal rails are installed.
Attach Rails and Panels
Once the fence posts are installed plumb and rigid, attaching the rest of the fence gets easier.
There are two main approaches, which depend on whether you’re building from scratch or using pre-made panels. Start by attaching mounting brackets to the posts per the manufacturer’s directions. Position the top and bottom rails in the brackets according to the planned fence height.
Constructing a fence from the ground up uses rails and individually placed pickets. For detailed steps, refer to this step-by-step fence-building video.
You’ll need a power drill and screws, a circular saw, a level, and clamps to build a fence from scratch.
Install top and bottom rails first, and position level side-to-side, following the sloping front to back. Secure into the posts with galvanized deck screws. Next, cut each picket to length, attaching the pickets one at a time, letting them follow the contour of the land. Use scrap lumber spacers cut to the proper width when needed to stagger the pickets. Predrill holes to prevent splitting.
Building a fence from scratch isn’t always necessary. Use modular fencing panels assembled from posts, rails, and pickets for the quickest installation.
Position each panel so it remains level, stepping up or down to follow the slope. Attach rails securely into the posts at the proper heights. Use pry bars as needed to maneuver panels into place on steep slopes.
Fill Gaps Under Stepped Fence Panels
Gaps under a stepped fence can leave room for your pets to squeeze through. To avoid this, fill the gaps using retaining wall blocks, bricks, or decorative stone.
Materials You’ll Need
Lastly, gather retaining wall blocks, brick or stone, and gravel.
Dig a trench under the fence just shy of the gap to be filled. Fill with packed gravel, then place blocks or bricks to follow the slope’s contour. Maintaining proper drainage under the fence is crucial to prevent erosion.
Alternatively, you can plant a ground cover plant like English ivy under the fence. The ivy spreads to fill the open areas under the panels with a living barrier.
I recommend keeping it trimmed back from the pickets.
So, Is Building a Fence on a Slope Worth it?
Constructing a fence on hilly terrain certainly presents some unique challenges compared to a flat yard. However, considering the slope during planning and layout allows you to adapt the fencing techniques to handle elevation changes across the fence line.
Whether you build from scratch with posts, rails, and pickets or use the faster modular panel system, a fence on uneven ground can be installed solidly, safely, and with an integrated look. Taking the proper precautions and allowing for adjustments makes it a doable DIY project.
The result is a privacy fence that provides security for your property, keeps kids and pets from roaming off, and gives your sloped backyard a finished look. Done properly, it seamlessly defines your property lines and complements the landscape.
FAQs About Building a Fence on a Slope
Is a stepped fence less sturdy than one that follows the contour of the slope?
Both types of fencing are equally sturdy when installed with proper techniques. The posts must be well-supported and anchored, and the pickets or panels must be securely attached. Visually, a stepped fence draws more attention to the grade change.
How do I determine the post length needed for a sloped fence?
Allow for the portion that must extend out of the ground for the tallest section, calculated from the top of the fence height needed. Add at least 6 inches for the lowest areas as a safety factor so the posts aren’t too shallow.
What is the maximum slope I can build a fence on?
There’s no absolute maximum slope, but things get quite difficult somewhere around a 45-degree angle. You may need terraces or retaining walls to create flatter areas. Consult with a professional fencing contractor who can handle steeper terrain more efficiently.
Can I build a fence parallel to the slope rather than following the contour?
It’s best to have the fence follow the lay of your land. A fence sloping straight along fall lines looks awkward and may suffer stability issues over time. Posts on the downhill side need to extend further out of the ground.
How do I attach a new fence to my neighbor's existing fence on a slope?
Use a transition panel or an end post that allows you to connect the two fence lines cleanly. They may meet at different heights and angles. Make sure all posts and hardware meet local code requirements, and discuss your plans with your neighbor first.
