I am building a split-rail fence out of locust rails and posts. The posts
will be set about 8 feet apart. I plan to dig postholes about 18 inches
deep, and set the posts into concrete.
What is the best method, and type of concrete ? My thinking was to use
Quickcrete fast-setting concrete. With similar things in the past, I have
mixed the concrete with water, and poured the mix in and around the post.
But, it seems that I have heard that other folks just pour the dry power in
the hole around the post, and allow the moisture in the surrounding soil to
harden the mix. Others pour in dry, and then just add a modest amount of
water in the hole.
What is the preferred method ??
Thanks for any advice on this !!
Your 18" post hole seems way too shallow for a fence. Better do some
more research on local conditions and methods and then worry about
concrete mix. Typically, some metal fence posts are 7' tall and 3'
into the ground. For a relatively short fence 2' would be a good
Let's please stick with the concrete question.... these posts will be 18
inches into the ground, and about 40 inches OUT of the ground. Split rails
will be placed across the posts. This is a simple three rail fence, not a
conventional fence with 6 foot posts.
Perhaps I led you wrong on the facts.
The best concrete to set posts is none. A couple inches of gravel in
the bottom and ALL the dirt back in the hole is the "proper" method.
And 18" is too shallow; a waste of, time, effort, money -and- concrete
if you're still set on using it. 30" is minimum and probably code,
and 36" is better.
Locust is the best choice for the posts, but you'd be better off
setting them on fire rather than in concrete. Nothing lasts forever,
try digging out a post set in concrete. By the time you're finished
you'll have changed your mind, if you live through it.
The concrete mix doesn't matter, any one will rot your posts as well
I guess I will at least answer your question -
Most big home centers carry "post-set" concrete. You dig the hole,
put the post in (with space around it) fill the space around the post
with dry mix, add water, and mix it up by pushing a pc of rebar up and
down in the "soup". Sets quickly, works fine and is very convenient.
I have seen this done, but I have never seen it work well - fences
were always leaning within 3 or 4 months. It is not possible to
mix the concrete in the hole - there will always be dry pockets no
matter how much poking and prodding is done.
Mix your concrete in a wheelbarrow and pour it into the hole.
Just curious, but when the wood rots away, how will you replace it? And,
you've been told (more than once) that the depth you've chosen isn't deep
enough, yet you insist on not heeding advice. You seem to have the answers,
so which one would you prefer to be told about the concrete?
If you are set on using concrete even though it is not needed, do not use
quickset. It sets too fast for the job you are doing at the experience level
you have. It is not that good for posts anyway ...
The 18" is good enuf for posts 3.5' above GL if you have normal soil but as
another said, pack the bottom inch or two with gravel. Also dig the hole in
the shape of an inverted paper cup -bigger at the bottom. There should be
about two inches or more of concrete on all sides (and corners! ) of the post
so make the hole wide enough to accommodate that.
Use the post setting dry mix concrete and place a couple of inches in the
bottom before setting the post. That insures concrete covering bottom.
Set the post in the hole, brace and level it so it is straight and add some
water, a cup or two; then fill in the rest of the hole with the dry mix.
Pack it a little, then wet it down with another cup or two of water and move
on to next post.
Bracing method can be found on the net. Basically, two 1x2 boards loosely
nailed to the post (on adjacent sides) and wedged into the ground. You'll
need to leave the braces on for a long time ...see the dry mix post setting
instructions. And, BTW, one cannot use regular concrete mix as a dry mix -the
proportions of portland cement, sand and aggregate are not the same.
Most posts fail at ground level so be sure to have a cap of concrete or at
least dirt up around the post for ~ an inch or two so the water will run away
from the post and not pool around it.
If OP INSITS on concreting them in secure them in place, tied off with
ropes or something, use dry mix its more convenient, leave set tied up
a week or so flood area a couple times, so its all hardened
concrete- a couple inches of gravel in bottom, then post, then 1/3 or so of
the hole with tamped gravel, then concrete. Give the water a place to go,
instead of bottom of post always being wet. Locust takes awhile to rot, but
anything rots eventually.
TX hill country. Fractured limestone is immediately below the soil. Only a
rock bar and alot of sweat, or, a diamond tipped auger can cut it. 18" is
typical depth for corner and tensioning posts on typical pasture fence.
Wood or steel posts.
Guess answers for this are kinda like gardening, depends on the
conditions... Sandy soil, clay, swamp, gravel, or rocky in your case.
I pre-mixed, wetter than usual, the concrete prior to pouring in the hole
with the post. Used rocks to stabilize the post during the pour, then fine
tuned the plumb after the pour. Set the corners first.
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