What Blackland clay does
A lot of Navarro and Ellis County sits on the Blackland Prairie, and the dark clay soil here is expansive. When it gets wet, it swells. When it dries out, it shrinks and cracks. In a hot, dry August you can see cracks in the yard wide enough to lose a pencil in. After a wet spring, the same ground is soft and sticky.
That swelling and shrinking happens every year, around every post in your fence. The clay grips the post and the concrete when it swells and pulls away when it shrinks. Over the years that works a post loose, a little at a time.
Why posts lean
Clay is the main culprit, but it usually has help:
- Shallow holes. A post that isn't set deep enough doesn't have much holding it once the clay loosens up.
- Mushroom-shaped footings. When concrete spills out wide at the top of the hole, the swelling clay can grab that lip and push it up. A footing that's straight or wider at the bottom resists that better.
- Wind. A 6-foot privacy fence is a big sail. Strong wind pushes on every section, and loose posts give.
- Rot. Wood posts rot at the ground line, where wet and dry meet. Once that happens, the post snaps or leans even if the concrete is fine.
- Gate weight. Gate posts carry the gate's weight on one side all day long. An undersized or shallow gate post is often the first thing to lean.
- Water. Sprinklers or a downspout soaking the same posts keep that ground swelling and softening.
How we set posts
There's no way to stop the clay from moving, but you can build so it doesn't win. Here's how we approach it:
- Dig deep enough. How deep depends on the fence height, the soil and whether it's a line post, corner post or gate post. Taller fences and gate posts go deeper. We don't skimp here, because it's the part you can't fix later without starting over.
- Set every post in concrete. Concrete gives the post a solid base to push against.
- Keep the footing from mushrooming. We keep the hole straight-sided and finish the concrete so water runs away from the post instead of pooling against it.
- Offer galvanized steel posts. Steel posts don't rot, so the weak spot at the ground line goes away. On a wood fence, the steel posts sit behind the pickets or get covered so the fence still looks like wood.
- Heavier gate posts. Gate posts get more size and more depth than line posts, because they carry more load.
We cover the rest of our build standards on the fencing page.
Wood posts or steel posts
Treated wood posts set in concrete can hold up for years, and they're what a lot of fences around here use. The usual way they fail is rot at the ground line. Galvanized steel posts cost more, but they don't rot and they stay straighter in moving clay. For a privacy fence you want to last, especially in a windy, open spot, steel posts are worth considering. We'll go over both when we quote your fence.
Can a leaning fence be fixed?
Often, yes. If the pickets and rails are in good shape and only a few posts are leaning or rotted, we can replace or reset those posts and straighten the fence without rebuilding the whole thing. If most of the posts have rotted off, or the fence is old enough that the pickets are worn out too, a new fence usually makes more sense. We'll tell you honestly which one you're looking at. Start with a free repair quote.
We work all over the Blackland, from Corsicana and Ennis to Waxahachie and Midlothian.
Common questions
Why do fence posts lean in North Texas?
Much of the area has expansive clay that swells when wet and shrinks when dry. That movement works posts loose over time, especially shallow posts, posts with mushroom-shaped concrete at the top, and wood posts that have rotted at the ground line.
Are steel fence posts better than wood in clay soil?
Galvanized steel posts cost more but do not rot at the ground line, which is where wood posts usually fail. They tend to stay straighter in moving clay.
Can a leaning fence be fixed without replacing it?
Often. If the pickets and rails are in good shape, the leaning or rotted posts can be replaced or reset and the fence straightened. If most posts and pickets are worn out, a new fence usually makes more sense.