Concrete for setting posts is overrated

tkneoJuly 23, 2014

I am a newbie to building fence. I read up on a lot of forums over the internet to figure out which posts can resist rot and what is the best way to set up posts and the majority of the content believes that posts should be set in concrete.

Attached is the picture of treated posts that i took out. These old posts were set in the ground without gravel, cement or anything else. The posts had been touching dirt for 10+ years .The property was so badly maintained that all the water always drained towards the posts. Despite all this, I see no rot.

Before i knew demolished the old fence i moved the posts around with my hands and they were so stable that i would have bet they are set in concrete. So, the stability argument for concrete isnt as promising as people make it to be.

Just thought i'd share this experience.

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saltidawg

I used Locust Fence Posts when I erected my split rail fence nearly 20 years ago. No sign of any rot with the posts so far. Rails have seen their share of rot.

Locust is VERY hard wood.

This post was edited by saltidawg on Wed, Jul 23, 14 at 17:29

    Bookmark   July 23, 2014 at 4:22PM
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dkenny

other than for corner posts or gate posts..
yep cement isn't needed..
the cement for the corner posts or gate posts help with the side loading in the soil. helps keep the post upright against the load..
otherwise the cement traps water and promotes rot

    Bookmark   July 23, 2014 at 4:35PM
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Trebruchet

I don't believe in concrete footings for posts. Give me well drained gravel any day.

    Bookmark   July 23, 2014 at 9:38PM
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kudzu9

Some soil is better than others for setting posts without concrete. I've always used pressure-treated posts set in concrete, but add about 4" of pea gravel or drain rock at the bottom for the post to rest on and allow drainage. I also slope the top of the concrete pour on all sides. Never had a problem.

    Bookmark   July 24, 2014 at 1:33PM
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tkneo

Kudzu, can you tell which soils are not ok for treated posts ?

I believe that contractors recommend concrete because that makes the job difficult and ends up being too much for the DIY homeowner. I believe that contractors don't have the incentive to recommend not using concrete. A contractor has an incentive to scare the homeowner about the potential problems if the homeowner didnt do the job right.

    Bookmark   July 24, 2014 at 2:29PM
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kudzu9

Any soil is ok for treated posts, it's just that with looser, loamy soils I would dig deeper and go with concrete. I know that many people don't use concrete and it works fine. I just have a preference for using concrete.

As for contractors wanting to make the job look hard by recommending concrete, I don't think that is much of a motivation. Mixing concrete is not that difficult. While I have an electric cement mixer, I don't even use it for small jobs. For those I mix individual bags in a rolling mixing barrel. Lots of people just mix it with a shovel in a wheelbarrow. I also know of people getting good results by filling the holes with dry post setting concrete mix and then dumping water on top. The concrete sets up well enough overnight to build the fence the next day.

Here is a link that might be useful: Odjob mixing barrel

    Bookmark   July 24, 2014 at 6:10PM
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HandyMac

There is actually more than one kind of pressure treatment.

Those posts look like CCA treated---the kind that was discontinued because arsenic 'leached' out. CCA is still available by special order and is MUCH better for ground contact.

ACQ and several subsequent varieties(YellaWood/etc) have varying amounts of copper and insecticides and are less suited for long term ground contact.

Clay and similar soils are hard on wood. By using gravel, that can be mitigated.

But, you have to prevent water from soaking into any wood in the ground, since that will guarantee failure. That means crowing concrete around the post and not allowing soil to contact the wood.

    Bookmark   July 24, 2014 at 6:13PM
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tjdabomb

I get these:

http://www.homedepot.com/p/Simpson-Strong-Tie-PBS44AZ-ZMAX-Galvanized-12-Gauge-4x4-Standoff-Post-Base-PBS44AZ/100374846

and put some rebar through the holes, set in cement and affix with deck screws into post. never had a prob, even in very heavy rain areas.

    Bookmark   July 24, 2014 at 6:36PM
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kudzu9

tjdabomb-
Those galvanized straps work fine in certain applications, like supporting one side of a car port. However, they are not approved for use in free-standing structures like fences because they can't resist wind loading forces. You'll see the disclaimer on the Simpson site, and most building departments won't give you a permit for their use in fences. Even the Home Depot web site notes that they are "for decks, patio covers and other top-supported structures."

This post was edited by kudzu9 on Thu, Jul 24, 14 at 20:57

    Bookmark   July 24, 2014 at 8:53PM
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dkenny

I would have to disagree with not soaking wood..
wood flooded in mine shaft for centuries is just fine..
look a the reclaimed sunk wood..from centuries ago..
priceless wood today..none were treated with chemicals..

no its no the soaking wet..
its the wet/dry/wet/dry cycles that destroy the wood..
dry is fine..wet is fine..between is not..and cycling between is the worst.

-dkenny

    Bookmark   July 25, 2014 at 9:33PM
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