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The power company says I can put my permanent service entrance on a 6" x 6" pressure treated post. My friend suggested I consider a metal post sunk in concrete, for greater longevity.

How long should I expect a treated post to last in the ground?

Here's the diagram the power company gives:

Puget Sound Energy Remote Meter diagram

Tester101
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Jay Bazuzi
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7 Answers7

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A PT post will last a long time in concrete, maybe 5 to 10 years in soil alone. I suggest you embed the post in concrete, trowel a peak around the post so water runs off, and don't let the PT post come in contact with the ground.

If you find the RV posts I mentioned earlier, they are steel, treated and when put in concrete will last 25 years or more.

ChrisF
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shirlock homes
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  • What is an RV post? Can you provide a link or something? – cigarman Mar 01 '11 at 19:38
  • http://www.pplmotorhomes.com/parts/rv-power-cords/multi-outlet-power-box.htm Google RV power outlets. many suppliers out there. – shirlock homes Mar 02 '11 at 14:21
  • Learn about AWPA specs for pressure treated lumber. The "maybe 5 to 10 years in soil alone" is not a good answer, because it varies wildly on how your post was treated. See my answer below for the treatment spec table. – mikeb Jun 12 '23 at 12:30
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It will not last long (7 yrs max) if the bottom of the post is wet. If you place stone at the base of the post, it should last 20+ yrs.

Brad Tombs
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  • That's common advice, and I believe it's true for most soil types, but for rich clay that doesn't drain well, it may make the situation worse: it will give water a place to pool. – Jay Bazuzi Oct 17 '12 at 03:52
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I am an experienced fencing expert and decking master. I know 100% that a spruce timber post will not exceed 4 years before collapsing with rot once buried in the ground.

Alan
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A PT post will last many many years below grade. I have built homes for 20+ yrs on the coast and every home is built on a girder and joist system which bares on 6x6 and 8x8 PT posts buried 8’ below grade and sticking up 8-10’ above. There is no concrete around these posts, it’s simply soil and water compacted around them and salt water at that. Homes have been built this way for 100’s of years and their PT posts whether treated back 100 yrs ago or treated last week do not rot. You must buy PT that can be used for below grade construction but even PT posts that don’t say below grade use will not rot in your lifetime.

Patrick Silver
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For the US - it depends on the treatment. The AWPA has ~10 different levels of treatment, from interior/damp rated to salt-water off the Gulf coast rated (UC1 and UC5C respectively)

So the correct answer is it will depend on what kind of post you have, what your soil is like and where you are.

Learn about the categories and pick the correct one use-case. I'm down this rabbit hole because I'm building a pole barn and all the big box stores around here sell is UC3B and UC4A, which is not what I need (I need UC4B).

See the table listed here for specs: https://awpa.com/info/technical/homeowners

enter image description here

mikeb
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The length of time will also depend on whether it has been cut after manufacture or not as well. The treatment does not always deep seep into the timber, therefore making any post delivery cuts may expose any untreated timber. Always best to retreat a fresh cut before installing.

TravisPUK
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I had 2×6 pressure treated lumber laying above ground on 8 inch cement block storing it out side for about 23 years exposed to snow. sun ECT. It has not even started to rot or crack this is concrete applied proof so take it from here but the individual outside stair tread has started to open face crack cause I neglected to seal it with linseed oil mixed with powdered milk that makes it water proof and durable many many more years.

George Bouthillier
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