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Vinyl fence posts - cement or not?

Posted by hrajotte (My Page) on
Wed, Aug 5, 09 at 9:46

I am getting quotes for a new vinyl fence (6' tall x 8' wide privacy panels.)
Most installers' quotes indicate they cement the posts for vinyl fences. One installer uses a pressure treated wood insert inside the hollow vinyl posts. He only cements if he cannot get the post holes deep enough, or at customer request.
Seeking comments pro or con for cementing. His cost for cementing is negligible, basically the cost of the cement. I'm in Massachusetts, if climate is a factor.
TIA


Follow-Up Postings:

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RE: Vinyl fence posts - cement or not?

I am not a professional but I have watched installers put in vinyl fencing. Every time they started a job they would put cement around the posts. If they had treated wood inside the posts I am not sure. They would set the posts in concrete one day then come back the next to finish the job. My job position at the time required me to go out and monitor jobs from time to time. I can honestly tell you that we never had a complaint about one of our fence installs. So in my opinion I would say go with the cement. As far as the climate I am not sure. I live in Louisiana so I am sure your climate is different than mine.


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RE: Vinyl fence posts - cement or not?

All vinyl fence manufacturers of which I am aware require a wood post (usually 'treated' or natural resistant to rot lumber like cedar or redwood) to be installed inside the vinyl 'sleeve'.

All require posts to be 'concreted' into place or permit a 'modified' type stone or gravel base(walnut sized stone with fine stone dust) tamped into place.

NO legitimate fence installer would suggest a wood post insert is an 'option'.

NO legitimate fence installer would suggest concrete or 'modified' stone an 'option' for post placement.

If your installer is telling you that you can properly install vinyl fence post sleeves without a wood inner post, or that concrete or modified tamped stone is not required:

RUN AWAY as fast as you can and find yourself a REAL fence professional....'cuz the one you found isn't.


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RE: Vinyl fence posts - cement or not?

I was under the impression that putting a wooden post into concrete was a bad idea. The concrete essentially acts like a sponge accelerating rotting of the post. Compacted stone was the preferred method to provide a means for water drainage around the post.

In any case, make sure that if the installer uses a pressure treated post that it is rated for ground contact.


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RE: Vinyl fence posts - cement or not?

Thanks for all the advice, fellas. I appreciate your tips. As it turns out, all the installers I spoke to DO use a PT insert in the post. Is the insert supposed to run the full height of the post, or just at the base? All I can figure is that it protects the base of the post from damage during cementing or tamping.
The installer who said cementing is optional DOES use the modified stone method described by manhattan42. I believe I will go with cementing, however.


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RE: Vinyl fence posts - cement or not?

No reason I am aware not to install an ACQ treated post directly into concrete.

If there is, please enlighten me.
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That said, the PT post should go the entire height of the vinyl 'sleeve' because it is into the PT post that all fence fasteners must attached.

Vinyl post 'sleeves' are just that: sleeves.

And not meant to structurally secure any other members of the fence assembly.


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RE: Vinyl fence posts - cement or not?

My dad's neighbor across the street thought he would go the easy route and avoid lugging the concrete and just back fill. You guessed it after the first good wind, it was a leaner, and he had to do it again right this time.


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RE: Vinyl fence posts - cement or not?

I had commercial quality vinyl fencing installed without wood posts nor gravel (they used concrete pre-made mix on the outside of the vinyl post (which is hollow inside)) by a professional as it seems, they did not use level so the fence is not necessarily straight, goes up at the end by several inches and is leaning at other places by say 1-2 inches. Is this the correct way to install?


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RE: Vinyl fence posts - cement or not?

The bottom of the post should NOT be in the concrete.

Put the post in the hole, then a few inches of gravel (pea gravel works well), tamp the gravel, then fill the rest of the hole with cement.

If you trap the bottom of the post in cement you have made a swimming pool that WILL trap and hold water and even treated posts will rot when installed this way.

You also need to make sure you have wood treated for burial, not just ground 'contact.'
They are not the same thing.


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RE: Vinyl fence posts - cement or not?

Thanks for the additional info. Fence was put up 2 years ago by a reputable fence company, posts cemented. No problems, even after last winter's snowblowing when snow was piled against the fence.


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RE: Vinyl fence posts - cement or not?

"I was under the impression that putting a wooden post into concrete was a bad idea. The concrete essentially acts like a sponge accelerating rotting of the post. Compacted stone was the preferred method to provide a means for water drainage around the post."

Only if you bed the bottom of the post in the concrete.

The bottom of the post hole below frost depth) should have a few inches of gravel an then place the post.
Add a few more inches of gravel, then concrete.

The bottom of the concrete needs to be below frost depth, so dig at least an additional 6 inches or so.

Without concrete footings (and often a wood member inside posts) vinyl fencing is not all that strong.


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RE: Vinyl fence posts - cement or not?

How should vinyl fencing posts be installed? The advice above appears to be:

6" gravel base+wood inserts treated for burial+160lb concrete per post.

I have 3 different contractors recommending 3 different ways for the same ActiveYards/Veranda Dogwood/ArrowWood panels (I am in New England):

1. 3' depth, 6 inches of gravel in the bottom of each hole and 160# of concrete per post
2. 3' depth, no gravel, 80lbs concrete, Pressure treated wood block insert (5x5x9)" for line posts, & 7' block for gate posts
3. 3' depth, no gravel, 80lbs concrete per post, Aluminum Post Stiffener or galvanized steel insert for gate posts, and no inserts for line posts because they are rated for hurricane winds

All 3 say that gravel is not needed because in MA the ground is rocky enough for drainage. Which of the above 3 options seem best, if any?


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RE: Vinyl fence posts - cement or not?

"All 3 say that gravel is not needed because in MA the ground is rocky enough for drainage."

The gravel is not for drainage but to prevent forming a 'swimming pool' around the bottom of the post that traps water.

Do not hire anyone that wants to embed the bottom of the post directly in concrete.
It WILL rot.


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RE: Vinyl fence posts - cement or not?

re "It WILL rot."

Thanks. The manufacturer says that wood posts are not necessary or recommended except in a gate or latch post. There, it is used to give the screws something to bite, not to strengthen the post. Two 1x4s, shaped like an L in the corner where the hardware is, is recommended.

The manufacturer also recommends the 6" gravel base despite there being no requirement for wood inserts, and the fences and posts are .135 inches thick. So, do you recommend wood inserts, and gravel with/without wood inserts?

Here is a link that might be useful: installation instructions


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RE: Vinyl fence posts - cement or not?

Any additional info. would be much appreciated.


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RE: Vinyl fence posts - cement or not?

"Two 1x4s, shaped like an L in the corner where the hardware is, is recommended. "

And if you bed this in concrete it will rot.

And we all know the manufacturer is interested in getting the longest possible life.

They want to get past any warranty, and that is about it.

Easier sells more stuff also.

It is like some paints that like to advertise they 'cover in one coat.'

Right on the can the warranty requires two coats.


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RE: Vinyl fence posts - cement or not?

There are 2 kinds of vinyl posts, vinyl sleeves, and vinyl fence posts. Sleeves are very thin and require additional support. These kinds of posts are really just ornamental covers. Vinyl fence posts on the other hand are structurally designed to support a vinyl fence. They use relatively thick walls, 0.135" to 0.150", or in some places like Miami 0.270" thick walls to withstand hurricane force winds. For the most part these are 9' posts installed 3' in the ground, cemented with anywhere from 80 to 160 pounds concrete. Vinyl fence gate posts on the other hand generally require additional higher up support to keep the weight of the gate from causing the post to lean. Gravel is sometimes used under vinyl fence posts, not for drainage, but to provide a footing in soft soils so the hollow post doesn't "sink" into the soil over time. Filing the hollow inside of the vinyl fence post that is underground with concrete also helps to keep it from sinking into the ground.


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RE: Vinyl fence posts - cement or not?

Several years ago I had a professional contractor install my new vinyl fence. I have noticed that it leans inwards and outwards in spots. I know they did not pour concrete for the posts. It sounds like the vinyl posts are hollow, I don't think there is a wooded post inside the vinyl post. I do know that during rainstorms I have standing water all along my fenceline.(probably why it leans). My question is, did that company do the work properly ? And what would you prefer I do to get this fence from leaning in and out.


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