Vinyl fencing is a durable and long lasting construction material with a lot of flex. By design, it may sway and creek as it potentially withstands wind speeds of over 100 mph. However, it should not wobble. Proper installation of a vinyl post must be into an adequate amount of concrete to prevent unsteady movement and sway.
What is fence wobbling?
Fence wobble occurs when a fence post has lost its secure position, creates space, and becomes loose in the post hole. If left unattended, the jarring of the post back and forth will cause adjacent posts to loosen in their footing and to begin to wobble as well–causing further damage down the fenceline.
I remember once eating a turkey-provolone under the hilltop shade of a giant oak staring down at a lengthy stretch of vinyl fence. A gentle breeze shifted direction and I noticed the entire vinyl fence creak and lean, in unison, slightly over to one side. Perplexed and curious I kept staring. I wondered if it would happen again. It did, the entire fence shifted into the opposite direction. I continued to watch and stare. Eventually, my turkey-provolone became lonely as I found myself lost in the slow, hypnotic shuffling of the vinyl fence–back-and-forth while the hardly detectable wind breathed in and out.
What Causes a Fence to Wobble or Sway?
- wind, rain, and freezing tempuratures: A fence has full exposure to the barrage of elements local to your area. Heavy wind and rain can loosen the soil around the post. And, freezing temperatures can cause the ground to swell (frost heaving). These conditions can loosen the post from its set position and cause wobble.
- new concrete damage: If a newly installed fence is exposed to any of the aforementioned weather conditions before the freshly poured concrete has a minimum of 24 hours to cure, the concrete may become weakened, misshaped, or loosened from its adherence around the post.
- rot and infestation: Wooden fences deal with the extra burdens of rot, dry rot, and insect infestations.
- impact damage to the post: any post that is struck with some source of force can be dislodged from its footing, fractured, or weakened
- POOR INSTALLATION. Unfortunately, a major cause of fence wobble is usually an outcome of poor installation.
Unfortunately, some fence installers, whether they be homeowners, friends, or contractors will install a fence post contrary to the manufacturer’s recommendation or contrary to general construction practices.
Some claim to have installed fence for years and swear that fence post holes only need one bag of 50lb concrete. Still, others suggest that they’ve heard from a reliable source that concrete isn’t needed at all–that a post can be installed with just dirt, rock, or coarse aggregate.
Perhaps, if done right, these installation methods can be long lasting. But, they are certainly not a universal installation method for all types of soil and terrain.
DON’T BE TEMPTED TO SHORT YOUR CONCRETE:
And, if you are going to spend all the time to dig a hole” 30 inches deep, and, if you’re spending so much money on your fencing material (fences are expensive), why wouldn’t you spend a little extra time and a little extra money to have the posts installed correctly so they’ll remain secure, inline and upright over the course of time?
Installed Correctly, but Still Have Wobble and Sway in Your Post?
As mentioned above, vinyl posts, rails and pickets all flex. If you were to take hold of a post and shake it vigorously you will see the vibrations reverberate down the next few sections of fence. The wind will cause this to happen as well. And, strong winds will dramatize the effect as the whole fence may screech and chatter while it’s being pummeled to and fro.
Not all Vinyl Fences are Equal
Vinyl fencing products vary in thickness and concentration of strengthening additives (chemical modifiers). Subsequently, some products are more flimsy than others. For example, the vinyl wall thickness of a 5×5 post will vary from 0.120 to 0.150 inches. That’s about a 1/32” variance that could be the difference from a low-strength flimsy flopping-around-in-the-wind-post to one with significantly more strength and rigidity.
High-quality vinyl tends to be manufactured with thicker material and/or have a higher quality vinyl formula. It may cost more, but it can significantly increase the resilience and rigidity of vinyl posts, rails and pickets.
Is the Problem in the Post, or in the Hole, or BOTH?
Problem with the POST
If the post is secure in the post hole, and yet you see your fence dramatically tossed around in the wind, or flexing over to the side with the load it is carrying, this is generally an issue with excessive flex and fence sway–the fix is in the post, it needs to be strengthened.
How and Where to Strengthen a Vinyl Fence Post
A fence post can be easily strengthened by adding a steel or aluminum insert (expensive, long-lasting), or by adding concrete and rebar (cheap, long-lasting, labor intensive).
Additional support may be needed in just a few key locations such as the end, corner or gate posts. In-line posts may also need additional support if they are particularly exposed–such as in a wind corridor or a very long stretch of fence. Depending on the exposure, you may need to strengthen every other post. Click on my post here to find more information about how to strengthen the fenceline and the post.
Problems in the Hole
Got a Wobbler?
Move the post back and forth. If it moves freely without any resistance, or, if the earth around the post moves as if it’s being churned from below the surface, the problem is in the hole.
Wobble Problems Could Go Deep
Grab your shovel and remove your sod or top cover from around the post–clearing a 15” diameter. Now, start digging. We are looking to answer the question, how is the post being secured? Dirt, rock, or concrete?
*QUIK TIP It will be easier to complete this step after removing the rails and pickets from the post.
4 Methods to Fix a Loose or Wobbling Vinyl Fence Post
- The Problem: No Concrete–just loose soil: A properly set post will have concrete filling the hole up to about 3-6 inches from the surface. Keep digging until you find it.
However, if you’ve dug all the way to the bottom of the post and did not run into any concrete, CONCRATULATIONS!! You have already completed the first step in the fix.
The Fix. Add concrete to the post hole. Click here, to read my blog about what kind of concrete and how much to use for your posts.
- Not Enough Concrete: If the fence was originally installed without enough concrete, there may not have been enough of a foundation to secure the post against the elements.
After all, a 6×8 section of privacy fence is quite the sail and it wont take mother nature long to loosen things up.
The Fix: Dig out the post hole down to the concrete. Make sure your post can be aligned and plumbed. You may have to secure the post or prop it into position with a 2×4. Add and mix additional concrete into your hole up to 3-6 inches of the surface.
*If only a pathetic amount of concrete surrounds the post, carefully break as much of it off and install the post with full concrete.
- Space Between Concrete and Post: Even the smallest gap or space between the concrete and the post can cause a significant amount of wobble. Just a ¼ inch gap at ground level could mean a 3” wobble at the top of your post.
The Fix: mix up a runny mix of fine grained thinset or grout. Pour it into the gap and then use a shim or wedge to secure the post into the proper position.
- Broken Post: A broken vinyl post, though not the most typical cause of wobble, is the easiest to identify.
The Fix: Dig out the post and replace and install into concrete.
*If you cannot find the manufacturer of your fence, and, if your rails are a custom shape, use a chop saw or circular saw, to cut a ½ inch piece off of one of your rails. Buy a blank vinyl replacement post and trace around the ½ inch piece of rail–to stencil-out where the new rail holes need to be. Use a rotozip, dremel tool, or even a jigsaw, to cut out the holes.
