Correctly setting your fence posts is one of the most important parts of installing a vinyl fence. Proper post spacing, depth, and alignment help create a straight, solid fence that will support the completed panels.
In this guide, Harley and Alex demonstrate how to measure, route, and set a vinyl fence post using concrete.
Tools and Materials
Before beginning, gather the following:
- Vinyl fence posts
- Vinyl fence rail
- Measuring tape
- Pencil or marker
- Router
- Routing template for rail hole
- Drill
- Stepping bit
- String line
- Bubble level or laser level
- Concrete (2 bags per post)
- Hose
- Tamping tool
Step 1: Mark the Rail Openings
Begin by measuring and marking the locations of the routed rail openings.
For the six-foot fence shown in the video:
- Mark the top rail opening at 1 7/8 inches from the top
- Mark the bottom rail opening at 74 1/8 inches from the top
Step 2: Check the Routing Template
Before routing the finished post, confirm that the routing template and router bit are the correct size for your fence rails.
Recommended Tip: Test the router on a scrap piece of vinyl or on the very end of a post that would be going into the ground. Insert the rail into the test opening to check the fit.
The rail should fit securely without the opening being too tight or too loose. Adjust the router or template as needed before routing the actual fence post.
Step 3: Route the Fence Post
Once the router has been tested and adjusted, line the routing template up with the measurements marked on the post.
Route the openings for the top and bottom rails. Double-check the placement and size of each opening before moving on to the next step.
Step 4: Drill Concrete Holes
Measure 6 to 7 inches up from the bottom of the post and drill a hole with your step-bit. Flip your post over and drill a hole in the same spot on the opposite side.
These allow the concrete to flow inside the bottom of the post and help with stability when it sets.
Step 5: Dig the Post Hole
Dig the post hole approximately 24 to 48 inches deep, depending on the fence design, ground conditions and local installation requirements.
The hole must be deep enough to hold sufficient concrete and provide a strong foundation for the fence post.
Always check local building requirements and underground utility locations before digging.
Step 6: Set the String Line
Run a string line along the planned fence line before placing the post.
The string line provides a consistent reference that helps keep each post properly positioned and the finished fence straight.
Place the post into the hole and line it up carefully with the string, using a bubble level to make sure the post is vertically straight.
Step 7: Add the Concrete
Place concrete around the outside of the post inside the hole.
It is also important to allow some concrete to enter the hollow vinyl post through the routed rail opening. Filling part of the inside of the post helps create a more secure base.
Gently shake or move the post slightly as the concrete is added. This helps distribute the concrete evenly around the post and reduces empty spaces.
Continue checking the level throughout the setting process because the post can move as the concrete is added.
Step 8: Tamp the Concrete
Use a tamping tool or the end of your leveler to compact the concrete around the post.
Tamping helps remove trapped air pockets and creates a firmer, more stable foundation. Be careful not to move the post out of alignment while compacting the concrete.
Check the post again with your level and adjust it before the concrete begins to set.
Step 9: Match the Post Heights
Once the first post is positioned, use it as the height reference for the remaining posts.
A laser level is the easiest way to transfer the correct height from one post to the next. Mark each post where the laser crosses it to maintain a consistent fence height.
A bubble level can also be used across the top of the posts when a laser level is not available.
Step 10: Add Water and Allow the Concrete to Set
Thoroughly soak your concrete so that there is standing water on the top of it.
Make sure the water reaches the concrete surrounding the post and the concrete placed inside the hollow post.
Complete one final check to confirm that the post is:
- Level
- Properly aligned
- Set to the correct height
- Positioned correctly along the string line
Allow the concrete to set before installing the fence rails and boards.
Repeat for Each Fence Post
Repeat the same measuring, routing, alignment, and setting process for each post along the fence line.
Taking the time to check every post will make installing the remaining fence components easier and help produce a straight, solid finished fence.
Watch the Installation Video
Watch Harley and Alex demonstrate each step in our video, How to Install a Vinyl Fence Post.
For more vinyl fence installation information, explore our additional NORTHERNLINE® installation guides and videos.