Fence Post - How Much Concrete


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Old 05-29-06, 10:32 PM
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Fence Post - How Much Concrete

I'm setting 4x4 PT posts for a 4ft wooden picket fence. I plan to dig post holes 2 ft deep. Is one 80lb bag of concrete sufficient to set the posts in? Can I put dry mix in the hole and then add the water or is it necessary to mix before placing in the hole? Thanks for the tips.
 
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Old 05-30-06, 07:32 AM
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Fence Post - How Much Concrete

How much concrete you use will depend on the size of the hole.

The advantages/disadvantages of using wet or dry concrete mix were brought out in answers to your earlier post.

Dick
 
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Old 05-30-06, 10:17 AM
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The holes will be about 10" diameter, 2 ft deep.

Regarding my prior post about wet vs dry concrete, the answer I received was not clear. I had asked about allowing the moisture from the ground to cure the concrete versus adding water to the dry mix once it is already in the hole. The reply I received was that it was "more work". I don't see how pouring water into a hole is "more work"

What I asked in the post that begins this thread was whether I needed to mix the concrete with water BEFORE putting it in the hole, or if it was okay to add the water to the dry mix already in the hole.
 
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Old 05-30-06, 10:33 AM
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Water in the hole...

When we built our fence we put the post in poured dry concrete around it while spraying water in the hole and mixing it with a metal post. Don't know if it was easier the premixing it but we didn't have a mixer or anything to clean up later and the posts are solidly in the ground. Unless you have a long time to build the fence I'd either add water to the hole and stir as you go or pre-mix I wouldn't just wait for the concrete to absorb the water from the ground.
 
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Old 05-30-06, 12:16 PM
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Fence Post - How Much Concrete

The proper way is to mix the concrete in a mixer with the correct amount of water. You will get the best, most durable concrete with the highest strength.

You can eventually get the concrete to cure by relying on exterior moisture, but it wll take a lomg time and the concrete will definitely have much lower strength. You really don't need much strength. You will have "good enough" concrete, just as the old Yugo was "good enough" to get licensed.

Adding water as you fill will give intermediate results and lower, unknown strength because of the variable method.

Your site, the soil, the number of holes and your abilities will determine the easiest method. If you are stretched out, you don't want to drag around too much material.

You can set and backfill sonotubes before pouring and plumb and brace the posts after pouring. This lets you pour almost continuously. The other choice is to go hole by hole and plumb and brace just before you pour and mix in the hole. This requires more concrete (bigger hole) to really get the material in, compacted and mixed.

At 10" wide for a 4' picket fence, you certainly have more than enough "beef" in the post foundation system.
 
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Old 05-30-06, 08:48 PM
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Thanks for the info. One more thing: Is it okay to fill the hole with dirt after the concrete has set, or does the concrete have to be on the surface?
 
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Old 06-05-06, 06:58 AM
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You should cover the concrete up.
 
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Old 06-06-06, 05:52 AM
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Originally Posted by blorzoga
Thanks for the info. One more thing: Is it okay to fill the hole with dirt after the concrete has set, or does the concrete have to be on the surface?
You want to avoid water or moisture touching the posts where it meets the concrete. So the best way to avoid this would be to have the concrete slightly above the ground level. The concrete should be sloped ever so slightly so water runs away from the post.
 
 

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