Building a 6' tall horizontal fence with 4x4 PT posts and a combination of
horizontal 1x6 and 1x4 PT members (with 3/4" gap between boards). Florida
building code calls for 4' spacing of posts and 24" depth with concrete
footers. I would like to skip the concrete and use pea gravel to avoid future
rotting. I also don't want the extra expense of transporting and pouring
concrete (even if I pour it dry and let groundwater cure it). I already placed
the order for 8' fence posts (buried 24" in gravel), but am wondering if I
should buy 10' posts and bury 4' in gravel. I have an auger with extensions,
so hole depth isn't an issue. Soil is very sandy in Florida and area where
posts go is elevated, but bordering a rainwater drainage ditch. The ditch only
fills after very heavy rains and will drain from sandy soil in about 1 day.
My 2 questions are:
1. For a 6' fence, 10' 4x4 or 8' 4x4? Pea gravel packed.
2. For 4x4 posts, should I use a 6" auger bit or 4" auger bit?
You said Florida building code calls for 4' spacing of posts and 24" depth with concrete footers -- not pea gravel. Why are
you asking about pea gravel?
As far as the auger diameter is concerned, the diameter of concrete footer that is required will determine the auger
Do you have any other stupid questions?
replying to Gordon Shumway, Doubts in S. Florida wrote:
None of the professional fence companies use concrete footers - some just pack
in plain soil, gravel will provide drainage and pack itself with time and wind
movement. It would be more helpful if you provided an opinion on 4' or 2' depth
with pea gravel and hole diameter.
replying to Gordon Shumway, HermitageRenovation wrote:
You are most likely a highly qualified skilled tradesman.
Your brutally harsh reply is either the result of you having a bad day and this
question just hitting you wrong or you're hoping for a flame war.
Isn't this a Homeowner forum? I guess the days of 'if you can't say something
nice'' are dead.
I am a central Florida homeowner, for reference. Last 3 fence jobs were all done
by professionals. 2 were peagravel, one concrete footers. The concrete posts
rotted within 7 years.
I was surprised that building code applies to fences but apparently it does:
The note about final inspection would imply to me that a building permit
This all being the case, you best adhere to the code. You may work
around it but be caught later if someone buys the property and it is not
up to code.
On Wednesday, April 6, 2016 at 12:44:06 PM UTC-4, Doubts in S. Florida wrote:
10' 4x4, concrete. Did someone say code? I thought so. 2' is
minimum. If digging is so easy, why not go deeper?
Sandy soil? I used a post hole digger. I have sandy soil and our code
requires 4' holes. It was a piece of cake (other than the occasional
root) to dig 4' holes for both my deck and my fence. Will a 4" auger
leave you enough room for fill of *any* type? I can tell you for a
fact that a post hole digger will and that it's pretty easy to "adjust"
a hole in sandy soil with a post hole digger.
Drop in the post, plumb it, pour in the concrete, add some water from
a hose and be done.
You are asking us to "approve" your desire to go against the code
for your area. Why we do that?
On Wed, 06 Apr 2016 16:44:02 +0000, Doubts in S. Florida
You might get 10 years out of PT 4x4s but I doubt it. I used .4 ACQ
posts and they were toast in about 7.
Best off if you have a marine contractor supply there who can get you
.6 or .8 CCA. Promise them you are working on a salt water dock and
don't let your kids lick the posts. If you just set them in the sand
and pack it in as you back fill you will snap the posts off before
they come loose. This is not beach sand, it is just about every size
from dust to concrete sand. That stuff will pack in pretty tight.
An auger is really overkill but if you have it you might as well use
it. I have an old style post hole digger and it takes about 2 minutes
to punch a 4' hole in this sand.
Do the math, at 4 x 4 aka 3 3/8 x 3 3/8" will not fit a 4" hole, so go with
bigger auger. My druthers would be 8" diameter x 4 feet deep. Even if the
code only calls for 24" deep, a bad hurricane could easily push a fence over
in sand, 4 feet deep in concrete will make it a lot sturdier, unless you
like to keep rebuilding fences. One trick to avoid the wood from swelling
when it is wet and cracking the concrete is to put some wire rings around
the post in several locations and a few inches below the surface. Coat
hanger wire will work as well, remember to twist the ends of the circle
I have heavy hard pan clay and need to go 4 feet deep for fence posts
because of frost, I only wish I had sandy soil to work with. It once took me
8 hours to sledge a 10 foot ground rod into the ground, and I was required
to put two of them in, I was sore and tired after doing that. You have got
it easy, don't lazy out.
replying to EXT, Doubts in S. Florida wrote:
Thanks for all the replies folks.
Decided on a 6" auger bit, digging 4' down, using 10' PT 4x4 posts. Will pack
with pea gravel below and on the sides. Possibly install a concrete collar at
the top. In this case, I think 4' depth with pea gravel will be better than 2'
concrete footer. And for all you code-junkies out there, I understand your
point, but I've seen too many new/newer PERMITTED fences with 8' post spacing
and most without concrete footers, how is this worse than those? The original
fence posts are 4x4's, spaced 8' apart, and have lasted 30 years and at least 30
hurricanes/tropical storms without concrete. One 4x4 that lines a driveway is
set in concrete and it has been replaced 3 times in as many years due to
rotting. And seriously, who has ever inspected fence posts before buying? If a
fence was built before the new codes - it would be grandfathered in (I know that
is not the case here).
Please explain how a rotten post with a concrete footer will be safer than a 4'
deep compacted gravel hole? If anything, the rotten post will snap off,
supplying shrapnel to hurricane-force winds. A loose post will just lean and
decrease wind loading as it leans.
On Thu, 07 Apr 2016 00:44:01 +0000, Doubts in S. Florida
I didn't follow this thread - sorry - but ..
you might have lost a few of us when you first mentioned
8 ft fence posts for a 6 ft fence 2 ft deep.
Dunno ... seems so wrong - as to negate discussion.
On Thu, 07 Apr 2016 00:44:01 +0000, Doubts in S. Florida
I agree with the analysis. I have been here well over 30 years and
seen a lot of stuff that survived and stuff that failed. Wood in
concrete fails faster, right at the top.
If you just pack 2 or 3 feet in the dirt, you are better off than
concrete. This ACQ stuff will still fail, even packed with dirt. It is
pure junk. I won't use anything less than .6 CCA with ground contact
and I prefer 2.5 CCA pilings.
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