Beyond the Mesh: A Master Guide to Chain Link Fence Posts
When most people think of a chain link fence, they picture the silver diamonds of the wire fabric. But as any pro installer will tell you, the fabric is only as good as the skeleton holding it up.
The posts are the most critical component of your fencing project. If the posts fail, the fence sags, the gates bind, and the structural integrity vanishes. Based on the 2018 Step-by-Step Method provided by the Chain Link Fence Manufacturers Institute, here is everything you need to know about selecting and installing the perfect posts.
1. The Anatomy of Support: Terminal vs. Line Posts
Not all posts are created equal. In a chain link system, posts are divided into two distinct categories based on the job they do:
Terminal Posts
These are your anchors. Terminal posts include Ends, Corners, and Gate posts.
- The Job: They must withstand the massive horizontal tension of the stretched fabric.
- The Spec: They are always larger in diameter than line posts (typically 2″ to 2-1/2″ O.D.).
- The Setting: They are set 2 inches higher than the width of the fence fabric to allow for hardware and tensioning.
Line Posts
These are the intermediate supports between your terminals.
- The Job: They support the vertical weight of the top rail and the fabric.
- The Spec: They are smaller (typically 1-5/8″ to 2″ O.D.).
- The Setting: They are set 2 inches lower than the fabric width, so the top rail can pass through the loop caps and sit flush with the top of the fabric.
2. Getting the Diameter (O.D.) Right
Outside Diameter (O.D.) is the standard measurement for fence pipe. Using the wrong size is a recipe for a “wavy” fence.
- Residential Standards: For most homes, a 2″ O.D. terminal post combined with 1-5/8″ O.D. line posts is the industry standard.
- Industrial Standards: For high-security areas or fences over 6 feet tall, you should upgrade to 2-1/2″ O.D. terminals and 2″ O.D. line posts to handle the increased wind load and weight.
3. The Spacing Engine: The “10-Foot Rule”
One of the most common DIY mistakes is uneven post spacing. According to the 2018 guidelines, line posts should be spaced at a maximum of 10 feet apart.
However, you should always divide your total run length into equal increments. For example, if you have a 31-foot run, don’t do three 10-foot sections and one 1-foot section. Instead, space your posts at roughly 7′ 9″ intervals. This ensures equal weight distribution and a much cleaner visual line.
4. Footing Physics: The Science of Stability
A post is only as stable as the hole it sits in. The 2018 guide emphasizes two critical factors for footings:
The “Bell-Bottom” Hole
Never dig a hole that is wider at the top than the bottom. This creates a “wedge” that frost can easily grab and push out of the ground (known as frost heave). Instead, ensure the hole is wider at the base than the top. This “bell” shape anchors the post into the earth.
The 1-2-4 Concrete Recipe
Avoid “soupy” concrete. The CLFMI recommends a heavy 1-2-4 mixture:
- 1 Part Portland Cement
- 2 Parts Clean Sand
- 4 Parts Gravel
Pro-Tip: Sloping (or “crowning”) the top of the concrete away from the post at ground level is essential. This prevents water from pooling at the base of the metal, which significantly extends the post’s life by reducing rust.
5. Security and Orientation
When installing your fittings, always ensure that the bolt heads face the outside of the fence. This isn’t just for aesthetics—it’s a security feature. If the threaded ends and nuts are on the inside, an intruder cannot simply unscrew your fence from the outside to gain entry.
The Gate Hinge Hack
For the ultimate security on gate posts, install the top male hinge upside down. This simple trick makes it impossible for someone to lift the gate off its hinges to get inside.
Summary
Building a fence that lasts 30 years isn’t about the wire; it’s about the math and physics behind the posts. By using the correct diameters, following the 1-2-4 concrete rule, and ensuring proper hole geometry, you can build a professional-grade barrier that stands the test of time.
For more detailed charts and spacing guides, refer to the official CLFMI 2018 Installation Brochure.
