Can You Put Vinyl Fencing on an Existing Wood Post?

I once lived in a home that had one of the only remaining wooden fences in the neighborhood. It required constant repair as the wooden cedar pickets warped, split, broke, and came unscrewed. I had to replace several posts every year that had rotted away from the base. For me, it truly was troublesome eye-sore.

Every time I’d pull into the neighborhood, I’d notice several pickets that needed repair. Meanwhile, I would question, couldn’t I just remove all the pickets and install a vinyl fence over the wooden posts? It seemed like such an easy upgrade that would instantly increase the curb appeal of my home and eliminate the constant hassle associated with the wooden fence.

Vinyl fence post sleeves can be used to cover wooden posts. They are commonly used to cover deck posts, pillars, or small scale fencing projects. Ideally, the base of a wooden post that is intended to be covered by vinyl should be prepped or waterproofed to prevent water absorption. Poorly prepped wooden posts encapsulated by vinyl are far more vulnerable to mold, decay and rot. 

Unfortunately, my wooden fence had not been installed properly and covering my wooden posts with vinyl was not an option. If I had gone ahead with the idea, it would have been a band-aid-solution and a huge mistake. 

Vinyl Fencing has Many Appeals: Long-Lasting Aesthetics and Long-Lasting Durability

Many homeowners install vinyl fencing to enhance their outdoor decor, landscaping, privacy, and their property’s curb appeal. Vinyl fencing is composed of materials that are highly resistant to discoloring and fading.

And, in addition to vinyl fencing’s quality aesthetics, it is also very durable and requires very little maintenance. Some manufacturers even provide a lifetime guarantee on their vinyl fencing products. Needless to say, it can be a very attractive option for someone looking to enhance their premises. 

Transforming a Wooden Fence into Vinyl: the Sleek Cover-up

Installing vinyl post sleeves over existing wooden posts could, potentially, be an upgrade to an existing fence or railing. To ensure that the upgrade will have long lasting potential there are a few considerations that may help with the decision. 

The Worst Problems with Installing Vinyl Over a Wood Post: Water and Aeration

A wood post will absorb water through its top and bottom end grains like a sponge. Moisture from the top of the post is drawn down and moisture from the bottom is drawn up. Because of its porous nature, even when wood is completely saturated, as long as a post is allowed ample ventilation, the wood will eventually air itself out. 

However, in construction, at least one end of the post (generally the bottom end) is installed in direct contact with another material and ventilation is diminished. If subject to constant moisture exposure, the portion of a wood post that cannot air itself out will lend itself to mold and decay.

This issue may be exacerbated by covering an existing post with a vinyl sleeve encapsulating the upper portion of a wooden post with a waterproof enclosure. 

What Part of a Wood Post Has the Greatest Risk of Dry Rot?

Also, if the posthole has drainage issues because of clay, bedrock, high water table, or constant watering, it is very difficult to prevent dry-rot and other wood decay issues. Even concrete, if left with prolonged water exposure, can become saturated with water and wreak havoc to a wooden post.

The part of the wood post most vulnerable to dry rot and other water saturation issues begins about two inches above the ground surface and extends down the post into to the soil another 18″ or so.

Can Waterproofing a Wood Post Prevent Water Saturation?

It is easy to assimilate that the long-term aesthetics and sustainability of a fence, in general, is highly dependent on the post and the installation method used to install it into the post hole.

In order for the post to maintain its structural tenacity, some installers seal the end of the post in attempts to prevent water accumulation from the base. There are many different methods used to attempt to seal the end of a post: water resistant concrete, paint, caulk, wood glue, tar, shrink wrap, hot dip, plastic cover–to name a few. 

Additional reasoning behind prepping the base of a post through waterproofing is supported by the fact that vinyl is a waterproof material.

If water is allowed to absorb up from the bottom and into a wood post covered by vinyl, it will have an even more difficult time airing out–especially if the ground’s surface and bottom of the post hole are consistently exposed to a wet or moist environment.

My Fencing Dilema cont’d. . .

The problem that kept me from covering my wood fence posts with vinyl was that I knew that the posts were going to always be in a wet environment. . .winter-long snow pack. . .spring rains. . .and above all. . .butted right up next to my sprinkler system–there was no chance those posts were going to stay dry–evident from the multiple upon multiple post re-installations that had been required of me. 

Even though the posts were set into concrete, the porous nature of concrete allowed and retained water absorption. My posts were subject to rot underneath the soil. If I had installed vinyl sleeves over the posts. . .it would have potentially exacerbated the problem and certainly would not have alleviated me from constant fence maintenance. 

My Beef With the Vinyl Sleeve Cover Over Wood Posts

Okay, I have to admit, I’m a little biased against covering any wood post with vinyl. And I have a beef against the idea. Well, 3 beefs actually:

Beef No. 1

Unless I am the one who installed the wood post, how am I supposed to know how well the base of the post has been prepped to either maintain aeration or to prevent water absorption?  

Vinyl Capped Posts are Entirely Reliant On the Wood Post for Stability

A fence made with Vinyl sleeves relies on the wooden posts for the support needed to carry the load of the fencing material and to provide support from wind and rain and other natural or unnatural stresses in may be subject to. All of the potential strength qualities that a vinyl post has is unused since the vinyl sleeve does not extend into the posthole.

Beef No. 2

Vinyl fencing alone is a very strong material impervious to rot, decay and termites. Why would I even want to cover a wood post when the vinyl post can carry the structural load of the fence all by itself? 

Vinyl Capped Posts are an Expensive Install Mostly Focused on Aesthetics

Vinyl fencing products are not cheap. Thousands of dollars may be required to purchase the materials alone. However, if vinyl sleeves are being used to simply cap over an existing wood post, the entire expense of the project will be towards aesthetics and none towards support and the structural tenacity that vinyl fence posts are capable of providing. 

Beef No. 3

It seems to me, that in many (not all) circumstances, the vinyl sleeve cover is a band-aid solution. A really, really expensive. . .band-aid. . . money pit. . .problem causing. . .potential nightmare. . .“solution”.

I could just see myself, in typical me fashion, spending thousands of dollars on vinyl fencing, purchasing posts only reaching ground level–and wishing only a few months later, (after having to fix a dozen more posts) that I’d bought full length posts, and set them all into concrete to be able to drop the mic and walk away.

Installing Vinyl over Wood Posts May Be an Appropriate Solution

I have thus described common water drainage and aeration issues a wood fence post may be subject to. I have also delved into some of the “beefs” that I personally have against the covering of wood posts with vinyl.

However, everything has been mentioned to raise awareness only. I do not intend to persuade you to think that this method of vinyl fencing is an inappropriate vinyl fencing solution for your property. It certainly could be the most viable option. The following circumstances lend themselves as candidates:

  1. Deck Posts: Often, wooden deck posts are mounted to the rim joist of the deck. There is good drainage and low risk of water absorption.
  2. Properly Installed Wooden Fence Posts: Posts mounted for several years and are still sturdy and solid. The posts have good spacing. You can run a stringline across the top and it is straight and true without dips or spurs. They haven’t succumbed to wobbling, sinking, heaving, or leaning.
  3. Good Soil Drainage: You’ve dug holes on the property and there is good soil drainage. You haven’t observed any existing wood post decay. The sprinklers don’t butt up right next to the fence.
  4. Level Property Line: If the property line has no major sloping complexities. Slope variations are must easier to handle with a vinyl install from scratch.
  5. Small Fencing Projects: In general, small fence projects lend themselves far better to the vinyl sleeve cover-up method of installation.
  6. Wood Posts Installed on Raised Concrete Footing: Exempt the risk of water seepage down into the base of the post.

Always Obtain a Second Opinion

One thing I know for certain is that regardless of how “cookie-cutter” a project may appear at first glance, there are always very unique characteristics and challenges that surface during a fence installation. And, there are always solutions.

Regardless of which installation you end up choosing, there are many complexities and the overall project can incorporate very hard labor. It would certainly be wise to obtain multiple bids on your project so you can receive feedback and multiple opinions based on the unique demands of your property. Being able to consult a contractor may save you a lot of time and money on your project.

Good luck with your vinyl install. The project will lend itself to many end-result benefits and is amazingly satisfying once completed. I sure hope your vinyl fence installation goes well.

Terri Williams

Terri Williams has over 20 years of experience in the construction, contracting, and remodeling industry. Most of the experience has incorporated installing fence, building decks, and exterior painting. Terri is also a DIY enthusiast and when not at work, loves to spend free time on personal projects such as additions, remodels and landscaping upgrades.

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