Because I used rocks inside the holes to stabilize the posts before the
pour. Wetter concrete assured me I had complete concrete saturation around
and under those rocks. No cavitation due to too dry a mix for that
situation. I used the inverted mushroom hole type. No gravel on bottom.
Stabilized bottom with suitably sized rocks, then top allowing at least 2"
above that topmost rock to concrete surface. Used level for plumb both
After the pour, I re-checked plumb and made minor adjustments if needed.
I did the tensioning posts similarly, except, I used a 3/4" offset
stringline for alignment with corners bottom and top. Stringline used for
rough, removed, then installed again after pour for final alignment. Of
course, the 90 degree opposite direction plumb was with a level.
A few neighbors in the area said to go with 5000 psi bagged concrete instead
of the 3000 psi version. They said they had no cracking problems with it
over time. Makes sense as sometimes 2 feet or more of the limestone rocks
will displace when using a rock pick or auger at the surface. Leaving
bigger area (hole) at surface to pour. Can't be helped. So, I used that
If your posts are dimensional (4x4 or 6x6) the following process
worked well for me. If your posts are roundish, then simply set them
in the holes with a few inches of gravel in the bottom, and use
quickcrete (regular or quick setting - it's up to you.) that has been
mixed to a pretty thick consistency. Level the post in all directions
and cross-brace for 24 hours before adding attachments.
If using dimentional lumber, the way I did the posts all around my
house, is to:
1. String a centerline along the length of the fence run.
2. Dig the hole to desired depth (in my case, 24").
3. Insert 10" sonnet tube that has been cut to desired length/height.
4. Backfill, leveling the tube along the way.
5. Mix quickcrete (regular or quick setting - It's up to you.)
6. Fill the tube with mixed quickcrete.
7. Set post anchor according to the centerline.
8. After concrete is dry, test fit posts, mark holes, drill holes, and
bolt posts into post anchors.
The fence is now over 14 years old. No rot, no leaning.
You can just pour dry mix around the post.if you wish add a little water on
top to speed setting.In a few days it will be hard, meanwhile the dry mix
will hold the post in place.
Be aware the posts will need to be replaced eventually ,then you will have
to deal with the concrete.
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