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Discussion Starter · #1 · (Edited)
Hi,
I'm building a 7' fence with 6x6 pressure treated posts. I've read that Home Depot's pressure treated wood is very low in PCF. Curious to get your opinion on this? What pcf level should I get for my posts?

Also, how many cement bags would you recommend I use? I'm from Ottawa, Ontario, Canada where we deal with long, cold winters. As such, I'm planning on digging 4 feet deep (keep in mind I'm using 6x6x12 posts). I was debating between 2-3? If you can also include whether or not the quick set rapid post concrete is worth the extra $$$ or just use the regular concrete
Ok, I'm done now..
Much appreciated.
Franko
 

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Personally I would not cement them in, Use crushed rock will make them just as solid without rotting which in time they will with cement.

Also be nice if you did a intro of yourself so know more about you. Guys tend to be a little more helpful if it is not a DIY just looking for advise on here.
 

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Check out my idea for fence posts.

A plastic base, PVC sonotube, filled with concrete (or crushed gravel for that matter)

Solves:
Moisture issues
Frost heave issues.

Done.

Maybe the crushed gravel might be better as it would drain !

I think it's a winner !
 

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Capra Aegagrus
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Personally I would not cement them in, Use crushed rock will make them just as solid without rotting which in time they will with cement.
I've always used concrete rather than crushed rock, but I won't argue that the latter won't work well.

However, I've never seen a post rot inside buried concrete. The rot happens at the surface of the ground (or concrete) where there's plenty of oxygen available to help the process.
 

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where there's plenty of oxygen available to help the process.
Makes sense to me.
But it's hard to get a straight answer on this issue.

What do you think of this design ?

I see the flaw of a sealed bottom is that if moisture does get in there ... it won't escape.

But to me, especially in the damp soils I often see ... the moisture source is the ground water and the soil.
 

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Of course, you can't eliminate oxygen.

So at grade level, if you can eliminate moisture, (like in the sealed system), does reduce rotting as much as possible ?
 

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Discussion Starter · #8 ·
Thanks you very much for all this information. Any clue what PCF grade qualifies for pressure treated? Wondering if Home Depot would actually carry such wood. From what I've heard they only carry 15% pcf pressure treated wood.
 

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Dig hole, tamp in bfr at bottom, place post, little gravel fill, tamp in dry mix concrete, or as an option add some water to speed cure.

Full concrete will hold moisture at the bottom, & eventually rot from bottom up.
 

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It adds a lot of fuss without a significant increase in longevity.
Isn't the "weakest link" moisture from the ground ?

What about wrapping the post in plastic ?

That's pretty easy.

Regardless of the other methods you use ... surely using the moisture barrier you apply to a basement wall would reduce the moisture in the post, just like it does in the basement.

As well, would the wetter the area, the more effective a plastic barrier would be ?
 

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To me, the reason why a post rots at ground level is that is where the post has the highest oxygen level and is the wettest.

Go up the post, it is drier.
Go down the post, it has less partial pressure of oxygen.

The only way to reduce water at the key area is to seal the entire section of the post that is in the ground.

Concrete or crushed gravel ... both will eventually assume the moisture content of the surrounding area.

A sealed post will also have less moisture fluctuations. And that probably helps alot.
 

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The old Florida method is no concrete. Since we mostly have sand that is pretty much all this going back in the hole.
 

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Wood does not rot well in water. There is some association (And which stuff doesnt have one) regarding wood pilings- and how they are still viable and in use today- issue is that the wood above water has issues, not below.

Even with low amounts of penetration, the important part is to paint over your cuts.
 

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Check out my idea for fence posts.

A plastic base, PVC sonotube, filled with concrete (or crushed gravel for that matter)

Solves:
Moisture issues
Frost heave issues.

Done.

Maybe the crushed gravel might be better as it would drain !

I think it's a winner !
Just curious,since I've done many fences in my life,what is a plastic base?A pvc sonotube?Do you mean Sch.40 pvc or what the hell,Crushed gravel for a 4' deep hole in a plastic sonotube?
Please specify?There may be something I'm missing?Always willing to learn.
 

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John Hyatt
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I never have to deal with frost heave over here. If I did I would move I hate the cold.

However two coats of copper green stops rot/bugs all together in ground contact wood.

The concept of a post siting on a pile of gravel in the hole is flawed IMO. The gravel is not a drain it is a collector so the post end sets in water all the time.

JonMon www.deckmastersllc.com
 

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John Hyatt
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Hmmmml I will have to think about that one.

Post sits on gravel in you northern guys area 3'- 4'-5' down. The end of the post is always exposed to water whither it sits in it or a few inches above it depending on the ground water level. Air... air causes what ? an environment that interacts with something that causes rot ? not that far down. where the ground levels out with the wood is where I have seen that happen.

So thinking about it it's all the same. Gravel or creet on the bottom makes no difference. A person will miss some lateral strength by subtracting the height of the gravel but if the gravel is lower than the wanted height of the needed over all depth then it's the same effect.

None of this has to be thought about if copper green is used.

J.
 

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Always Learning
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I have done posts with and without concrete for misc fencing. Personally I like them set in concrete. Will they rot? Maybe over time but not quick enough to worry about and they still can/will rot in stone. If you create a small dome around the post it keeps the water flowing away from the post. This can be done below the soil a few inches if you don't want to see the crete. Always going to find different ways to skin the cat on here.
 
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