Setting fence posts in concrete/ bad ????

[sendero]

I could beleive that, but only a little. If the wood shrinks because it dries out, it will quickly swell when it gets wet again. It isn't likely to let a torrent of water in there /forums/images/graemlins/smile.gif

I suspect this whole line of question is mostly speculation. A treated post is going to last a long time regardless of the conditions it is put into. I wonder how many controlled experiments have been done. They'd take 20+ years, so I'm betting around zero /forums/images/graemlins/smile.gif

 

[beenthere]

How much are you willing to bet? /forums/images/graemlins/grin.gif


Here is one bit of information that will make for interesting reading on preservative tests of wood.

treated wood tests

 

[sendero]

Oh about 50 cent. /forums/images/graemlins/smile.gif Here's the thing, do you really believe that one way is *vastly* superior to another? I read all these theories and they remind me of dentists talking about brushing teeth (one year it's back and forth, the next it's up and down) or doctors talking about not eating cholesterol (when further study proved the obvious, serum cholesterol has jack to do with dietary cholesterol).

I'm just a born skeptic, and frankly it has worked out pretty well for me /forums/images/graemlins/smile.gif

I can believe that there might be a "better" way, but most of the explanations I read here don't hold much water IMHO. People act like concrete is waterproof and make other physically dubious assumptions /forums/images/graemlins/smile.gif I have to hear an explanation I buy before I adopt a bit of information or technique and I'm not hearing them !!!!!! And besides, mine is the right to be wrong /forums/images/graemlins/grin.gif

 

[sendero]

You added the "treated wood test" document, so I took a look at it. I can't find anything in it that relates to how you set a post (or stake) into the ground. All I can find is various treatments and how well they work.

I did skip over the verticle tables (someone should be fired for those /forums/images/graemlins/smile.gif) - is that where they explain the difference between ground, concrete, concrete bottom and gravel bottom?

 

[damndozerman]

My first post here.Your best bet is to always tamp in rock around wooden post of any kind.Use concrete with any steel you put in the ground.

 

[eee]

I have a pole barn I built 13 years ago and we put 2 old bricks in the bottom of each hole before setting the post, after setting the post we filled each hole with concrete. On the barn I built the posts out of 2x6 treated,nailed the boards together and made the 6 x 6 posts,of course I staggered each board end for end as we nailed the boards together IE: a 24' long post you would not want 2 twelve foot long boards and another set of 12 long boards butted up against each other in the same post without an overlap,thus you would have a weak spot. The reason I built the posts rather than buy a 6" post I was told the heartwood on a 6" post might not be treated,on hindsight I think it might have been over kill to have done all the extra work.
We built a big wrap around porch on my house 2 years ago using 6 x6 posts(did not build these posts's),again we put 2 bricks in the bottom of each hole and then we just dumped one bag of quickcrete in each hole ran water in the hole hole on top of the quickcrete and topped the hole off with dirt to the surface level if needed.

 

[Dargo]

My barn was also built about 13 years ago. They used #2 rock and tamped it in the bottom of the 4' hole. Some of my 6 X 6 posts are pretty long because I have a 16' side wall. Before the posts were set on the tamped gravel, they screwed a few lag bolts in each post about 2' up from the bottom. After the posts were set in the hole, then concrete was filled all the way to the barn floor, which is 10" of 5000 psi fiber mesh concrete with 6 gauge wire in it and rebar across each entrance. The idea of the lag bolts are to stop any possibility of the post from settling. Those bolts are out into the concrete.

By this discussion, my posts should not rot anytime soon. There is no place that the post is open to any of the elements. They are either encased in concrete, or inside my barn. By the way, that method of setting posts is not my idea, so I cannot take credit or discredit for it. I used the premier post frame builder in my area, waited nearly a year for him to get to me, and that is his standard method of setting the posts. He has several other building methods that he uses that are somewhat unique. So far, so good! /forums/images/graemlins/smile.gif

 

[ALBALD1]

It is strange how you hear both sides on the cement thing. I was talking to a guy last weekend who had a Morton building. He said they cemented the poles. I noticed they used 3 2x6's instead of a 6x6 & it was treated on the bottom only to a foot or so above ground. He said they give a lifetime guarantee on it. They been around a long time, so I would think they know how to build it. Interesting note, he hit it with his bobcat & did a little damage. They fixed it under warranty. Another thing I see a lot is people say to get .60 pressure treated instead of .40, but at the local Lowes I notice they have .25 & .40. There is no .60 that i've seen. All this definitely makes you worry when trying to build something to last.

 

[PBinWA]

My take on the whole thread has to do with understanding what causes the wood to rot. It's typically the water. It can be accelerated by other agents (chemicals) that combine with the water to accelerate the rotting but in general the water is what causes the rotting.

If you set a post in concrete and the top of the concrete is below the ground level then the water will still hit the post and do its damage. If you are going to use concrete you need to make sure that you encase the wood completely and then have the concrete above the ground level and ideally sloped down and away from the post so no water can rest against the wood.

If you just tamp the wood into the ground and your ground is suitably porous and dries out enough then the wood should be able to survice nicely. I suspect a properly concreted post would outlast a post just set in the ground. But this may also depend on the type of ground that the post is set in. I also know that concrete is porous so it may actually slow down the drying process in certain environments which means you may need thicker walls of concrete around the post in really wet conditions.

Most home centers only stock the lowest .25 retention PT lumber. You can special order higher retention stuff through them but it will take a while. The contstruction oriented specialty wood suppliers will typically stock some .40 and can usually order the higher retention stuff for you with out giving you that blank stare that you get at the Home Center when you start asking about stuff they son't stock.

 

[Gatorboy]

Concrete will rot the post faster for at least two reasons:

1. The lime in the concrete will eat away at the wood.
2. The concrete creates a nice pocket for rain water, and the post will just sit in constant contact with moisture, causing it to rot sooner.

All wood posts will rot eventually, but when it's time to replace the posts, the ones without concrete will be alot easier to replace.