Wood fence post coated with tar?

I had a wood fence built last year, the code calls for 4x4 PT posts embedded in concrete 12" deep, which is what I did. I have always wondered how long this PT post would last in the hot and humid Miami sun and rain.
A few days ago I drove by a house where they just had a new wood fence up. I noticed the bottom of the fence post where it meets the ground all of the post had been painted with something black with the consistency and texture of tar. I am pretty sure this is something done to prevent the post from getting in contact of water. Wish I had thought of that, and curious if this is a common procedure. I hope my posts will give me at least 5 years before I have to do it all over again.
MC
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Before I planted my fence posts, I coated the bottom of the posts with that tar-like black stuff that you can coat driveways with. Driveway sealer of some sort, black, tar-based. I don't really know what if any difference it will make. I bought mine in a 5 gallon bucket at Home Depot for somewhere around $20 or so.

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http://www.pentox.com/EnFPM.html
Melange pour pieux de cloture
:-)

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On Apr 22, 9:04 am, christian snipped-for-privacy@yahoo.com wrote:

MIx for piles of fence?
Joe
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on 4/21/2009 11:25 PM (ET) Zootal wrote the following:

Better to use a special tar mix that is used to coat the concrete walls below grade before backfilling. Most times it is brushed on then heavy plastic sheeting is stuck to the tar to provide additional waterproofing. It is available at the big box stores, and may be available in smaller stores.

--

Bill
In Hamptonburgh, NY
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Somehow I doubt it would do much good and was probably done to impress the fence installer's client. Tar coating the wood would do little to prevent water from eventually soaking the bottom of the post and little to prevent decay. Once water got into the wood the tar probably would slow down the wicking away of the water during dry periods enhancing rot. If it isn't a substance that soaks deep into the wood and also kills the rot fungus it will do little else.
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